Densification of silicon carbide films using remote plasma processing

Abstract

A method and apparatus for densifying a silicon carbide film using remote plasma treatment is provided. The operations of remote plasma deposition and remote plasma treatment of the silicon carbide film are alternated to control the film density. A silicon carbide film of a first thickness is deposited, followed by remote plasma treatment, and then a silicon carbide film of a second thickness is deposited, followed by another remote plasma treatment. The remote plasma treatment can cause radicals of a source gas in a substantially low energy state (e.g., hydrogen radicals in a ground state) to flow toward the silicon carbide film deposited on a substrate. The radicals of the source gas in a substantially low energy state promote crosslinking and film densification in the silicon carbide film.

Description

[0001] This application is a divisional application of the invention patent application with application number 201780086632.6, application date November 30, 2017, and invention name “Densification of silicon carbide films using remote plasma treatment”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Patent Application No. 15 / 382,137, filed December 16, 2016, and entitled “DENSIFICATION OF SILICONCARBIDE FILM USING REMOTE PLASMA TREATMENT,” which is hereby incorporated by reference in its entirety and for all purposes. Technical Field

[0004] The present disclosure relates generally to the formation of silicon carbide films, and more particularly to remote plasma deposition and remote plasma processing for densifying silicon carbide films. Background Art

[0005] 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. Summary of the invention

[0006] The present disclosure relates to a method for densifying a silicon carbide film. The method includes: providing a substrate in a reaction chamber; depositing a silicon carbide film of a first thickness on the substrate; and exposing the silicon carbide film of the first thickness to a remote hydrogen plasma process, wherein the silicon carbide film of the first thickness is densified; depositing a second thickness of the silicon carbide film on the silicon carbide film of the first thickness; and exposing the silicon carbide film of the second thickness to a remote hydrogen plasma process, wherein the silicon carbide film of the second thickness is densified.

[0007] In some implementations, each of the first thickness and the second thickness is between about Peace between. In some implementations, depositing the silicon carbide film of the first thickness includes: (a) flowing one or more silicon-containing precursors into the reaction chamber; and (b) flowing one or more hydrogen radicals generated from a remote plasma source to react with the one or more silicon-containing precursors for a first period of time, wherein depositing the silicon carbide film of the second thickness includes repeating operations (a) and (b) for a second period of time. In some implementations, each of the one or more silicon-containing precursors has (i) one or more silicon-hydrogen bonds and / or silicon-silicon bonds, and (ii) one or more silicon-carbon bonds, silicon-nitrogen bonds, and / or silicon-oxygen bonds. In some implementations, each of the one or more silicon-containing precursors is selected from: cyclic siloxanes, linear siloxanes, alkoxysilanes, alkylsilanes, and silazanes. In some implementations, at least 90% of the hydrogen radicals are ground state hydrogen radicals. In some implementations, wherein exposing the silicon carbide film of the first thickness to a remote hydrogen plasma treatment comprises: (c) flowing a hydrogen source gas into a remote plasma source; (d) flowing an inert gas with the hydrogen source gas; (e) generating hydrogen radicals in a remote plasma source from the hydrogen source gas; and (f) flowing the hydrogen radicals to the silicon carbide film of the first thickness, wherein exposing the silicon carbide film of the second thickness to a remote hydrogen plasma treatment comprises repeating operations (c) to (f) on the silicon carbide film of the second thickness. In some implementations, the inert gas is helium, and the hydrogen source gas in the helium has a hydrogen concentration of 1-10%. In some implementations, exposing the silicon carbide film of the first thickness to a remote hydrogen plasma treatment further comprises: (g) flowing a co-reactant gas with the source gas, wherein the co-reactant gas comprises oxygen (O2), nitrogen (N2), carbon dioxide (CO2), carbon monoxide (CO), water (H2O), methanol (CH3OH), ozone (O3), nitrous oxide (N2O), ammonia (NH3), diazene (N2H2), methane (CH4), ethane (C2H6), acetylene (C2H2), ethylene (C2H4), diborane (B2H6), or a combination thereof, wherein exposing the silicon carbide film of the second thickness to a remote hydrogen plasma treatment further comprises repeating operation (g) for the silicon carbide film of the second thickness. In some implementations, the pressure in the reaction chamber is between about 0.2 Torr and about 5 Torr. In some implementations, the silicon carbide film of the first thickness is exposed to remote hydrogen plasma treatment for a duration between about 5 seconds and about 50 seconds, and the silicon carbide film of the second thickness is exposed to remote hydrogen plasma treatment for a duration between about 5 seconds and about 50 seconds.

[0008] The present disclosure also relates to an apparatus for densifying a silicon carbide film. The apparatus includes a reaction chamber, a plasma source remote from the reaction chamber, a substrate support for holding a substrate in the reaction chamber, and a controller configured with instructions for providing the following operations: providing a substrate in the reaction chamber; depositing a silicon carbide film of a first thickness on the substrate; and exposing the silicon carbide film of the first thickness to a remote hydrogen plasma treatment, wherein the silicon carbide film of the first thickness is densified; depositing a silicon carbide film of a second thickness on the silicon carbide film of the first thickness; and exposing the silicon carbide film of the second thickness to a remote hydrogen plasma treatment, wherein the silicon carbide film of the second thickness is densified.

[0009] In some implementations, each of the first thickness and the second thickness is between about Peace In some implementations, depositing the silicon carbide film of the first thickness comprises: (a) flowing one or more silicon-containing precursors into the reaction chamber; and (b) flowing one or more hydrogen radicals generated from a remote plasma source to react with the one or more silicon-containing precursors for a first period of time, wherein depositing the silicon carbide film of the second thickness comprises repeating operations (a) and (b) for a second period of time. In some implementations, at least 90% of the hydrogen radicals are ground state hydrogen radicals. In some implementations, wherein exposing the silicon carbide film of the first thickness to a remote hydrogen plasma treatment comprises: (c) flowing a hydrogen source gas into a remote plasma source; (d) flowing an inert gas with the hydrogen source gas; (e) generating hydrogen radicals in a remote plasma source from the hydrogen source gas; and (f) flowing the hydrogen radicals to the silicon carbide film of the first thickness, wherein exposing the silicon carbide film of the second thickness to a remote hydrogen plasma treatment comprises repeating operations (c) to (f) on the silicon carbide film of the second thickness. In some implementations, the inert gas is helium, and the hydrogen source gas in the helium has a hydrogen concentration of 1-10%. In some implementations, the pressure in the reaction chamber is between about 0.2 Torr and about 5 Torr.

[0010] These and other embodiments are described further below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A A cross section of an exemplary silicon carbide film deposited on a substrate is shown.

[0012] Figure 1B Silicon carbide vertical structures on the sidewalls of a gate electrode structure of a transistor are shown.

[0013] Figure 1CSilicon carbide vertical structures on the exposed sidewalls of copper lines in an air gap type metallization layer are shown.

[0014] Figure 1D Silicon carbide pore sealants for porous dielectric materials are shown.

[0015] Figure 2 Representative embodiments of cage-silane precursors are shown.

[0016] Figure 3 A schematic diagram of a device with a remote plasma source is shown.

[0017] Figure 4A An example of the chemical structure of oxygen-doped silicon carbide before densification is shown.

[0018] Figure 4B An example of the chemical structure of oxygen-doped silicon carbide after densification is shown.

[0019] Figures 5A-5D Various stages of depositing and densifying a silicon carbide film on a substrate are shown.

[0020] Fig. 6A Fourier transform infrared (FTIR) absorption spectra are shown with various vibrational peaks for detecting certain bond types in delaminated and non-delaminated silicon carbide films.

[0021] Figure 6B-6E Shows Fig. 6A A magnified view of the FTIR absorption spectrum in FIG. 5 with various vibrational peaks for detecting certain bond types in delaminated and non-delaminated SiC films. DETAILED DESCRIPTION

[0022] In the following description, numerous specific details are set forth to provide a thorough understanding of the concepts presented. The concepts presented may be practiced without some or all of these specific details. In other cases, well-known processing operations are not described in detail so as not to unnecessarily obscure the concepts described. Although some concepts will be described in conjunction with specific embodiments, it should be understood that these embodiments are not intended to be limiting.

[0023] 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 fabrication performed thereon. 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, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micromechanical devices, etc.

[0024] introduction

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Dangling bonds can generate silanol groups (Si-OH) in the deposited silicon oxycarbide or silicon oxycarbonitride film. As a result, the film may have an undesirably high dielectric constant. Film quality may also be affected because direct plasma conditions tend to extract carbon from the deposited film.

[0030] 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.

[0031] 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 cyclosiloxanes that would otherwise provide porosity in the ultra-low k dielectric material.

[0032] 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.

[0033] 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.

[0034] The environment of the substrate surface during deposition

[0035] 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 can include one or more silicon-containing precursors having one or more Si-H bonds and / or one or more Si-Si bonds accompanied by 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.

[0036] Some applications using silicon carbide membranes are Figure 1B-1D In some embodiments, the silicon-containing precursor may include a silicon-oxygen precursor, a silicon-nitrogen precursor, and / or a silicon-carbon precursor. The silicon-oxygen precursor may include one or more Si-O bonds, the silicon-nitrogen precursor may include one or more Si-N bonds, and the silicon-carbon precursor may include one or more Si-C bonds. In some embodiments, for example, the silicon-containing precursor may include a single reactant A having a Si-O bond and a Si-C bond or a Si–N bond and a Si–C bond. In some embodiments, the silicon-containing precursor may include a reactant B having a Si-O bond or a Si–N bond, and a reactant C having a Si-C bond. It should be understood that any number of suitable reactants may be used within the scope of the present invention. The chemical structures of exemplary silicon-containing precursors will be discussed in further detail below.

[0037] The silicon-containing precursor includes one or more Si-H bonds and / or one or more Si-Si bonds. During the deposition process, the Si-H bonds and / or Si-Si bonds are broken and serve as active sites for forming bonds between the silicon-containing precursors in the deposited silicon carbide film 101. The broken bonds can also serve as sites for crosslinking in thermal treatments 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.

[0038] In some embodiments, the process conditions may 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. Thus, 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. Typically, the described reaction conditions 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 distance above the substrate 100, for example, at about 0.5 microns to about 150 millimeters above the substrate 100. In practice, the activation of the precursor may occur in the gas phase at a considerable distance above the substrate 100. Typically, the relevant reaction conditions will be uniform or substantially uniform across the entire exposed surface of the substrate 100, but some applications may allow for some variations.

[0039] 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 atom free radicals. In some embodiments, all, or substantially all, or a considerable portion of the hydrogen atom free radicals may be in the ground state, for example, at least about 90% or 95% of the hydrogen atom free 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.

[0040] As explained elsewhere, hydrogen can be supplied to a remote plasma source to generate hydrogen atom radicals or hydrogen radicals. Once generated, the hydrogen atom radicals can be in an excited energy state. For example, hydrogen in an excited energy state can have an energy of at least 10.2 eV (first excited state). Excited hydrogen atom radicals can cause non-selective decomposition of silicon-containing precursors. For example, hydrogen atom radicals in an excited state can easily destroy Si-H bonds, Si-Si bonds, Si-N bonds, Si-O bonds, and Si-C bonds, which can change the composition or physical properties or electrical properties of the silicon carbide film 101. In some embodiments, when the excited hydrogen atom radicals lose their energy or relax, the excited hydrogen atom radicals can become hydrogen atom radicals in a substantially low energy state or a ground state. Hydrogen atom radicals in a substantially low energy state or ground state can selectively destroy Si-H bonds and Si-Si bonds, while generally retaining Si-O bonds, Si-N bonds, and Si-C bonds. In some embodiments, process conditions may be provided such that the excited hydrogen atom radicals lose energy or relax to form substantially low energy or ground state hydrogen atom radicals. 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.

[0041] 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 precursor (e.g., trimethylsilane). Relatively mild conditions that support the deposition of this film are selected.

[0042] 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, free radicals or even ions in higher energy states can potentially exist near the wafer plane.

[0043] 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 workpiece sidewalls), resulting in poor conformality.

[0044] 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 the 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. 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 (equimolarity).

[0045] 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 instead of one or more silicon-containing precursors and radical species. 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 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 via the same flow path as the silicon-containing precursor; for example, a path including 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.

[0046] In certain embodiments where a co-reactant is used and the co-reactant is introduced into the chamber together with the substance to be converted into free radicals (e.g., hydrogen), the co-reactant may be provided to the reaction chamber in a relatively small amount compared to other gases in the reaction chamber, including the free radical source (e.g., hydrogen), and any one or more carrier gases (e.g., helium). For example, the co-reactant 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 1-10 sccm of oxygen. When the co-reactant is introduced into the reaction chamber together with the silicon-containing precursor (e.g., through a showerhead), the co-reactant may be present in a higher concentration; for example, about 2% or less, or about 0.1% or less. When the co-reactant is a relatively weak reactant (eg, a weak oxidant such as carbon dioxide), it may be present at even higher concentrations, such as about 10% or less, or about 4% or less.

[0047] 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.

[0048] 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.

[0049] Figure 1B-1D Shown is a cross section of a structure containing a silicon carbide film for various applications. Figure 1B Silicon carbide vertical structures on the sidewalls of a gate electrode structure of a transistor are shown. Figure 1C Shown are vertical structures of silicon carbide on the exposed copper line sidewalls in an air gap type metallization layer. Figure 1DSilicon carbide pore sealants for porous media materials are shown. Each of these applications will be discussed in further detail below.

[0050] Chemical structure of the precursor

[0051] 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. 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 silicon-containing precursors 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 silicon-containing precursors do not contain OC bonds or NC bonds; for example, one or more precursors do not contain alkoxy groups (-OR), 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.

[0052] In some embodiments, at least some of the carbon provided for the silicon carbide film is provided by one or more hydrocarbon moieties on the silicon-containing precursor. These moieties can be selected from alkyl, alkenyl, alkynyl, aryl, etc. In some 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 some embodiments, the hydrocarbon group is linear. In some embodiments, the hydrocarbon group is cyclic.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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).

[0057] 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).

[0058] In some embodiments, the silicon-containing precursor can be an alkoxysilane. The alkoxysilane includes 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).

[0059] In addition, disilane, trisilane or other higher silanes can be used instead of monosilane. The example of such disilane from alkylsilanes is hexamethyldisilane (HMDS). Another example of 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.

[0060] 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.

[0061] 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.

[0062] For depositing oxygen-doped silicon carbide films, examples of suitable precursors 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.

[0063] 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 c The 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, surface temperature, surface coverage, structural details of the surface, and the kinetic energy of the impinging material. Certain 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.

[0064] Graded SiC film

[0065] Technology nodes continue to shrink in the integrated circuit manufacturing industry. With each technology node, device geometries shrink and the pitch becomes smaller. High aspect ratio gaps in such technology nodes may need to be filled with insulating materials, such as insulating materials with low dielectric constants (low-k). Semiconductor integration operations may involve filling high aspect ratio gaps with low-k dielectric materials. This is the case for shallow trench isolation, intermetallic dielectric layers, passivation layers, etc.

[0066] For example, from the 45 nanometer (nm) technology node to the 14 nm technology node, device features shrink laterally, bringing conductive materials closer together. Unwanted conductive coupling can occur when conductive materials are closer together, which can lead to parasitic capacitance, delays in signal propagation, and signal crosstalk due to capacitive effects. However, as technology nodes become smaller, low-k materials as interlayer dielectrics (ILDs) for conductive interconnects can reduce parasitic capacitance, signal delays, and signal crosstalk. Some applications, including fin field effect transistor (finFET) structures and dynamic random access memory (DRAM) bit structures, require low-k materials as sidewall spacer materials.

[0067] In many integrated circuit applications, silicon nitride (Si3N4) is often used as an insulating material due to its step coverage, thermal stability, etchability and etch resistance, and high breakdown voltage. However, as technology nodes become smaller, the dielectric constant of silicon nitride (about 7-8) may be too high.

[0068] Silicon oxide (SiO2) has a relatively low dielectric constant of approximately 4.0 and can provide significantly reduced capacitance as an interlayer dielectric for conductive interconnects. However, silicon oxide may not have sufficient resistance or selectivity to etching operations in various device integration operations.

[0069] Silicon carbide materials including doped silicon carbide materials and undoped silicon carbide materials can be used as insulating materials in integrated circuit applications, which not only provide low dielectric constants, but also provide step coverage, thermal stability, wet etching resistance, dry etching selectivity to oxides / nitrides, and high breakdown voltage. For example, the addition of oxygen atoms and / or nitrogen atoms can adjust the properties of silicon carbide materials. In some embodiments, oxygen-doped silicon carbide films can be used as insulating materials in integrated circuit applications, which provide low dielectric constants, wet etching resistance to withstand device integration operations, and dry etching selectivity to oxides / nitrides.

[0070] Various techniques for densifying thin films can improve the properties of thin films. Thermal annealing and direct plasma treatment are commonly used to complete the densification of materials. Direct plasma treatment or PECVD treatment can densify thin films by ion bombardment, wherein direct plasma or PECVD treatment can use inert gas species or reactive gas species (such as ammonia (NH3), nitrogen (N2) or oxygen (O2)). Ion bombardment using reactive gas species can convert one or more elements in the thin film, such as carbon in silicon carbide film, nitrogen in silicon nitride film or oxygen in silicon oxide film. For example, NH3 plasma can be used to densify SiCN film. Ions and free radicals from NH3 plasma contribute to film densification, but ion damage may occur during direct plasma treatment. Moreover, using direct plasma treatment of films deposited in features (e.g., trenches, grooves, etc.), film densification may be uneven, wherein the densification of the film may be greater at the top and bottom of the feature than at the sidewalls of the feature.

[0071] When manufacturing integrated circuits, the silicon carbide film may undergo one or more device integration operations. Such device integration operations may include various deposition, etching, cleaning / stripping and annealing processes. In the device integration operation, the silicon carbide film may undergo etching, ashing and / or annealing processes. For example, the silicon carbide film may undergo one or more wet etching, dry etching of SiO2, oxygen plasma ashing of photoresist and steam annealing processes. Therefore, it may be necessary to develop a silicon carbide film with improved chemical stability, improved dry etching selectivity relative to SiO2, improved plasma ash resistance and improved thermal stability. Densified silicon carbide films may also provide at least some of the above improvements if they cannot provide all of the above improvements.

[0072] Densified silicon carbide films have a greater bonding density of Si-C and / or Si-O bonds than undensified silicon carbide films. Densification can remove dangling silicon and / or carbon bonds and promote cross-linking of silicon and / or carbon atoms. Typically, the chemical structure of the deposited silicon carbide film may include several terminal methyl groups (CH3) and increased hydrogen content. For example, an oxygen-doped silicon carbide film before densification may include several terminal CH3 bonds and may have a high hydrogen content. Hydrogen atoms may bond with oxygen atoms to form silanols (Si-OH), and hydrogen atoms may bond with silicon atoms to form terminal Si-H bonds. Figure 4A An example of the chemical structure of oxygen-doped silicon carbide before densification is shown. Figure 4A As shown, the oxygen-doped silicon carbide structure includes a plurality of terminal CH3 bonds, wherein the carbon atoms are coordinated by oxygen and hydrogen atoms. Many carbon atoms, or at least a majority of the carbon atoms, are not cross-linked.

[0073] Remote plasma treatment of silicon carbide film can increase the bonding density of Si-C bonds and reduce the number of terminal CH3 bonds and Si-H bonds, thereby densifying the silicon carbide film. Remote plasma treatment can remove hydrogen atoms from terminal CH3 bonds and Si-H bonds and promote crosslinking to form at least Si-C bonds. Si-Si bonds can also be formed by crosslinking. Hydrogen from Si-CH3 groups can be removed during treatment and crosslinked to form Si-C-Si bonds. In some embodiments in which oxygen-doped silicon carbide films are deposited, densification increases the bond density of Si-O and Si-C bonds by removing terminal CH3 bonds, Si-OH bonds, and Si-H bonds. Remote plasma treatment can extract hydrogen from oxygen-doped silicon carbide films and promote crosslinking, so that more Si-O and Si-C bonds can be formed. The hydrogen of the Si-CH3 group can be removed during treatment and crosslinked to form Si-C-Si bonds. The hydrogen of the Si-OH group and the Si-H group can be removed during treatment, and these groups can be crosslinked to form Si-O-Si bonds. In addition, the remote plasma treatment can react the hydroxyl groups of the Si-OH groups to form water (H2O) and cross-link with each other to form Si-O-Si bonds. It should be understood that the remote plasma treatment can lead to other possible mechanisms or other possible reaction pathways for increasing the bond density of Si-O and Si-C bonds and reducing the amount of terminal CH3 bonds, Si-OH bonds, and Si-H bonds. Figure 4B An example of the chemical structure of oxygen-doped silicon carbide after densification is shown. Figure 4B As shown, the oxygen-doped silicon carbide film includes few to no CH3 bonds, wherein the carbon atoms are generally cross-linked and coordinated by silicon atoms. The carbon atoms or at least a majority of the carbon atoms are cross-linked and not coordinated by hydrogen or oxygen atoms.

[0074] Without being limited by any theory, increased Si-C bond density can improve certain properties of silicon carbide films. In some embodiments, increased Si-C and Si-O bond densities can improve certain properties of oxygen-doped silicon carbide films. After densification, the doped or undoped silicon carbide film can have higher chemical and thermal stability. For example, the doped or undoped silicon carbide film after densification can exhibit one or more properties of low etch rate, high etch selectivity relative to silicon oxide, high O2 plasma ashing resistance, and high thermal stability.

[0075] The present disclosure can use remote plasma treatment to densify silicon carbide film, and in certain embodiments, remote hydrogen plasma treatment is used to densify silicon carbide film. It should be understood that the silicon carbide film of the present disclosure includes undoped silicon carbide film and doped silicon carbide film, such as silicon oxycarbide (SiCO) film, silicon carbon nitride (SiCN) film and silicon oxycarbon nitride (SiONC) film. Densified silicon carbide film can show improved chemical stability, thermal stability, etching resistance, selectivity relative to oxide / nitride and plasma ashing resistance. In some embodiments, silicon carbide film is densified in a layer-by-layer manner. The film density and composition of the silicon carbide film across the film thickness can be controlled in a layer-by-layer process. Using remote plasma treatment to densify silicon carbide film in a layer-by-layer method provides a more uniform film densification while minimizing the damage that may be caused by ion bombardment in direct plasma treatment.

[0076] Figures 5A-5D Various stages of depositing and densifying a silicon carbide film on a substrate are shown. Deposition and remote plasma treatment cycles may occur in an alternating manner to form a densified silicon carbide film. Different, fewer, or additional operations may be performed. Figures 5A-5D The operations shown in .

[0077] Figure 5A A cross section of an exemplary silicon carbide film deposited on a substrate is shown. A silicon carbide film of a first thickness 501 can be deposited on a substrate 500. The substrate 500 can be any wafer, semiconductor wafer, partially manufactured integrated circuit, printed circuit board, display screen, or other suitable workpiece. In some embodiments, the substrate 500 can include a plurality of high aspect ratio features, wherein each feature can have an aspect ratio greater than 2:1, greater than 5:1, or greater than 10:1. The first thickness 501 of the silicon carbide film can be deposited with such high aspect ratio features with good step coverage. Good step coverage can be used in various integrated circuit applications, such as sidewall spacer applications.

[0078] The first thickness 501 of the silicon carbide film can be controlled according to a predetermined deposition time to achieve a desired thickness. In some embodiments, the deposition time can be between about 5 seconds and about 500 seconds, or between about 10 seconds and about 200 seconds. In some embodiments, the desired thickness of the first thickness 501 can be between about 10 seconds and about 200 seconds. Peace The deposition time may correspond to a desired thickness of the first thickness 501. The first thickness 501 may be controlled to allow sufficient penetration of a subsequent remote plasma treatment to densify the first thickness 501.

[0079] Deposition of a silicon carbide film of first thickness 501 may occur using the remote plasma deposition techniques described previously herein. In some embodiments, the first thickness 501 is deposited by flowing one or more silicon-containing precursors into a reaction chamber toward the substrate 500, and one or more free radicals of a source gas flow from a remote plasma source to react with the one or more silicon-containing precursors for a first period of time (e.g., a deposition time). The free radicals of the source gas may be in a low energy state or ground state when reacting with the one or more silicon-containing precursors. The reaction with the one or more silicon-containing precursors provides relatively mild process conditions in an environment adjacent to the substrate 500.

[0080] In some embodiments, free radicals can be generated by a source gas, which includes hydrogen, nitrogen, NH-containing substances (such as NH3), oxygen, oxygen-containing substances (such as H2O, CO2 or N2O), or mixtures thereof. For example, the source gas may include hydrogen. Most of the free radicals can be free radicals in a substantially low-energy state, such as free radicals in the ground state. Hydrogen free radicals in a substantially low-energy state or ground state can selectively destroy Si-H and Si-Si bonds, while generally retaining Si-O, Si-N and Si-C bonds. In some embodiments, at least 90% of the free radicals in the source gas are hydrogen free radicals in the ground state. A state in which most of the hydrogen free radicals are in a substantially low-energy state or ground state can be achieved by various techniques. Some devices, such as those described below, are designed to achieve this state.

[0081] The process conditions as described above may be applicable to depositing silicon carbide films using remote plasma deposition with one or more silicon-containing precursors.Process conditions such as pressure, temperature, RF power, gas flow, and gas composition may be adjusted during deposition to affect the characteristics of the remote plasma.

[0082] In some embodiments, the pressure in the environment adjacent to the substrate 500 can be any suitable pressure for generating reactive radicals in the reaction chamber. For example, the pressure can be about 35 Torr or less, such as between about 10 Torr and about 20 Torr or between about 0.2 Torr and about 5 Torr.

[0083] In some embodiments, the temperature in the environment adjacent to substrate 500 can be any suitable temperature to facilitate deposition. For example, the temperature can be between about 50°C and about 500°C or between about 250°C and about 400°C.

[0084] In some embodiments, the RF power applied to the remote plasma source can vary depending on the type of plasma source, wafer size, and other operating conditions. Typically, for example, the RF power for an inductively coupled plasma for a 300 mm wafer can be between about 300 watts and about 10 kilowatts, or between about 1 kilowatt and about 6 kilowatts. Higher RF powers can be applied to generate more free radicals in the remote plasma source.

[0085] In some embodiments, the gas composition during remote hydrogen plasma deposition may include one or more silicon-containing precursors. Each of the one or more silicon-containing precursors includes at least one Si-H and / or at least one Si-Si bond. In addition, each silicon-containing precursor may also include at least one Si-O bond, at least one Si-N bond and / or at least one Si-C bond. In some embodiments, each silicon-containing precursor does not contain OC or NC bonds; for example, the precursor does not contain alkoxy (-OR), where R is an organic group (such as a hydrocarbon group) or an amine (-NR1R2) group, where R1 and R2 are each hydrogen or an organic group. One or more silicon-containing precursors can be selected to adjust the composition of the silicon carbide film and achieve high step coverage. In some embodiments, each of the one or more silicon-containing precursors is selected from: cyclic siloxanes, linear siloxanes, alkoxysilanes, alkylsilanes and silazanes. For example, the one or more silicon-containing precursors may include alkylcarbosilanes, linear siloxanes, cyclic siloxanes, silazanes, or any combination thereof when forming a silicon carbide film, an oxygen-doped silicon carbide film, a nitrogen-doped silicon carbide film, or an oxygen- and nitrogen-doped silicon carbide film. The one or more silicon-containing precursors may provide substantially all of the mass of the deposited first thickness 501 of silicon carbide film, with a small amount of hydrogen or other elements from the remote plasma providing less than about 5 atomic percent or less than about 2 atomic percent of the film mass.

[0086] In some embodiments, in addition to one or more silicon-containing precursors, the gas composition during remote hydrogen plasma deposition may include one or more co-reactants. One or more co-reactants may be introduced into the reaction chamber by the same flow path as the silicon-containing precursor, wherein one or more co-reactants are not exposed to plasma, or one or more co-reactants may be introduced into the reaction chamber by the same flow path as the remote plasma, wherein one or more co-reactants are exposed to plasma. Co-reactants may be selected to adjust the composition of the silicon carbide film of the first thickness 501. Depending on the selection of co-reactants, co-reactants may increase or decrease the carbon, oxygen or nitrogen content of the silicon carbide film. Co-reactants may include CO2, CO, H2O, CH3OH, O2, O3, N2, N2O, NH3, N2H2, CH4, C2H6, C2H2, C2H4, B2H6 or a combination thereof. In some cases, one or more co-reactants may include CO2, O2, N2, NH3 or a combination thereof. The one or more co-reactants may be introduced into the reaction chamber in relatively small amounts compared to other gases in the reaction chamber, including the source gas of the free radicals and any carrier gases.

[0087] In some embodiments, the gas composition during remote plasma deposition may include one or more carrier gases. In particular, the source gas may be provided with a carrier gas. Examples of carrier gases include, but are not limited to, helium, neon, argon, krypton, and xenon. The concentration of the carrier gas may be significantly greater than the concentration of the source gas. For example, hydrogen may be provided in a helium carrier gas at a concentration of about 1-10% hydrogen. The presence of a carrier gas may help increase the ionization of the source gas and reduce recombination. Although lower pressures generally help increase the ionization of the source gas and reduce recombination, the presence of a carrier gas may play the same role. Thus, even at higher pressures, when a carrier gas such as helium flows with the source gas, a large portion of the free radicals may be generated with minimal recombination. A higher pressure in the reaction chamber during deposition may improve the conformality of the silicon carbide film. A higher pressure in the reaction chamber may correspond to a pressure greater than about 3 Torr or greater than about 5 Torr, for example, about 7 Torr.

[0088] It should be understood that the composition of the silicon carbide film can vary depending on the choice of precursor, the flow of the precursor, and the flow of the co-reactants. 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 present in the place of Si-H bonds and / or Si-Si bonds of the precursor molecule and / or through additional condensation reactions on the growth surface (if sufficient thermal energy is provided).

[0089] Figure 5B shows the densification by remote plasma treatment Figure 5A501 . After the silicon carbide film of the first thickness 501 is deposited on the substrate 500, the first thickness 501 is exposed to a remote plasma treatment 510 to densify the first thickness 501. The remote plasma source used to generate free radicals of the source gas during deposition can also be used to generate free radicals of the source gas during treatment. Therefore, the silicon carbide film deposition can be performed in the same reaction chamber as the reaction chamber for the silicon carbide film treatment. This enables alternating deposition and treatment cycles to be performed in the same tool. As a result, the first thickness 501 can be deposited and the silicon carbide film of the first thickness 501 can be exposed to the remote plasma treatment 510 without introducing a vacuum break (e.g., an air break). Vacuum breakage reduces yield and introduces oxidation into the semiconductor device, which can result in higher resistance and reduced performance.

[0090] Densification of the silicon carbide film of the first thickness 501 can be achieved by remote plasma treatment 510. Exposing the silicon carbide film of the first thickness 501 to the remote plasma treatment 510 can include: flowing a source gas into a remote plasma source, generating free radicals of the source gas in the remote plasma source from the source gas, and flowing the free radicals of the source gas to the silicon carbide film of the first thickness 501. In some embodiments, exposing the silicon carbide film of the first thickness 501 to the remote plasma treatment 510 also includes flowing an inert gas with the source gas. In some embodiments, the source gas can include hydrogen, nitrogen, NH-containing substances (such as NH3), oxygen, oxygen-containing substances (such as H2O, CO2 or N2O), or mixtures thereof. For example, the source gas can include hydrogen.

[0091] The silicon carbide film of first thickness 501 is exposed to remote plasma treatment 510 without delivering silicon-containing precursors. In other words, while the deposition of the silicon carbide film of first thickness 501 involves flowing one or more silicon-containing precursors, the treatment of the silicon carbide film of first thickness 501 stops the flow of silicon-containing precursors. However, remote plasma treatment 510 can treat the silicon carbide film of first thickness 501 by delivering radicals in a substantially low energy state to the silicon carbide film of first thickness 501. A majority of the radicals can be radicals in a substantially low energy state (e.g., ground state). In some embodiments, at least 90% of the radicals of the source gas are hydrogen radicals in the ground state. During remote plasma treatment 510, radicals of the source gas can also flow to the silicon carbide film of first thickness 501 in addition to other gases, such as one or more co-reactant gases and an inert carrier gas. The remote plasma treatment 510 may remove hydrogen from Si-CH 3 groups, Si-OH groups, and Si-H groups in the silicon carbide film and promote cross-linking to increase the overall bond density of Si-C and / or Si-O bonds.

[0092] Densification of the silicon carbide film of the first thickness 501 using remote plasma treatment 510 can be controlled according to a predetermined treatment time. In some embodiments, the treatment time can be between about 2 seconds and about 100 seconds, or between about 5 seconds and about 50 seconds. Longer treatment times can correspond to enhanced densification. The determination of the treatment time can depend on the thickness of the first thickness 501, where thicker layers may require longer treatment times to allow the layer to be more fully densified.

[0093] In addition to the processing time, the densification and processing efficiency can also be controlled by adjusting one or more process conditions (e.g., pressure, RF power, gas flow, and gas composition). The pressure, RF power, gas flow, gas composition, and other process conditions can be adjusted during the remote plasma processing 510 to affect the characteristics of the remote plasma, so that different bond densities can be generated in the silicon carbide film of the first thickness 501.

[0094] The pressure in the reaction chamber during the remote plasma treatment 510 can be adjusted to increase the ionization of the source gas and shorten the residence time of the free radicals of the source gas. Shortening the residence time will reduce the impact of free radical recombination. Lower pressure allows molecules to move faster, which leads to increased ionization of the source gas, shortened residence time and reduced recombination of free radicals. In some embodiments, the pressure can be between about 0.2 Torr and about 5 Torr, or between about 1 Torr and about 3 Torr. However, it should be understood that the pressure in the reaction chamber during the remote plasma treatment 510 can be greater than 3 Torr or greater than 5 Torr, wherein other process conditions (e.g., inert carrier gas) lead to sufficient ionization and shortened residence time.

[0095] The RF power applied to the remote plasma source during the remote plasma processing 510 can be adjusted to increase the generation of free radicals of the source gas. The increased RF power will increase the ionization of the source gas, thereby generating a large portion of the free radicals of the source gas. Typically, for example, the RF power of the inductively coupled plasma for a 300 mm wafer can be between about 300 watts and about 10 kilowatts, or between about 1 kilowatt and about 6 kilowatts.

[0096] During remote plasma treatment 510, the source gas may flow with an inert carrier gas. The inert carrier gas may include, but is not limited to, helium, neon, argon, krypton, and xenon. The concentration of the inert carrier gas may be significantly greater than the concentration of the source gas. In some embodiments, the concentration of the source gas relative to the inert carrier gas may be between about 1% and about 10%, or between about 2% and about 5%. Without being limited by any theory, the reason why the inert carrier gas has a significantly higher concentration relative to the source gas is that the inert carrier gas contributes to "Penning ionization", resulting in significant dissociation of the source gas and producing most of the free radicals. A significantly greater concentration of inert carrier gas may also minimize the recombination of free radicals. For example, hydrogen may be provided in a helium carrier gas at a concentration of about 1-10% hydrogen. An inert carrier gas (e.g., helium) with a lower molecular weight may contribute to Penning ionization with higher efficiency than an inert carrier gas with a higher molecular weight. In addition, flowing an inert carrier gas having a low molecular weight (e.g., helium) and a low concentration source gas relative to the inert carrier gas (e.g., a small amount of hydrogen in helium, with a hydrogen concentration of about 1-10%) can generate most of the free radicals even at high pressures (e.g., greater than 3 Torr) while minimizing recombination. Thus, the presence of a suitable inert carrier gas at an appropriate concentration can help densify the silicon carbide film of the first thickness 501 regardless of the pressure of the reaction chamber.

[0097] During the remote plasma treatment 510, one or more co-reactants can be flowed to adjust the bond density and composition of the silicon carbide film of the first thickness 501. One or more co-reactants can be introduced into the reaction chamber through the same flow path as the remote plasma, wherein the one or more co-reactants are exposed to the plasma. Depending on the selection of the co-reactants, the co-reactants can increase or decrease the oxygen, nitrogen or carbon content of the silicon carbide film. The co-reactants may include CO2, CO, H2O, CH3OH, O2, O3, N2, N2O, NH3, N2H2, CH4, C2H6, C2H2, C2H4, B2H6 or a combination thereof. In some cases, one or more co-reactants may include CO2, O2, N2, NH3 or a combination thereof. The presence of oxygen or oxygen radicals tends to extract carbon from Si-C bonds. In other words, the presence of oxygen can convert carbides into oxides. Carbon can be removed from the silicon-containing precursor on the substrate, and in some cases, carbon can be replaced by oxygen. Thus, increasing the oxygen concentration in the remote plasma during the remote plasma treatment 510 can effectively adjust the carbon content of the silicon carbide film of the first thickness 501. Additionally or alternatively, the presence of nitrogen or nitrogen radicals tends to extract carbon from Si-C bonds. Thus, increasing the nitrogen concentration in the remote plasma during the remote plasma treatment 510 can effectively adjust the carbon content of the silicon carbide film of the first thickness 501.

[0098] Figure 5C Shows Figure 5BA cross-section of a silicon carbide film of the type shown in FIG. 5 , wherein a second thickness is deposited on a silicon carbide film of the type shown in FIG. 5 . A second thickness 502 of the silicon carbide film may be deposited on a silicon carbide film of the type shown in FIG. 1 . The operation of depositing the second thickness 502 may be the same as or at least similar to the operation of depositing the first thickness 501. In other words, the process of depositing the second thickness 502 may repeat the process of depositing the first thickness 501. For example, if depositing the first thickness 501 includes flowing one or more silicon-containing precursors into a reaction chamber and flowing one or more radicals of a source gas generated by a remote plasma source to react with the one or more silicon-containing precursors for a first time period, then depositing the second thickness 502 includes repeating the above operations for a second time period. In some embodiments, the first time period is the same as the second time period. In some embodiments, the first time period is different from the second time period. Different time periods may correspond to different thicknesses. In some embodiments, the thickness of the second thickness 502 may be between about 100 Å and about 200 Å. To date In addition, controlling the deposition time and various process conditions (e.g., pressure, temperature, RF power, gas flow, and gas composition) can adjust the thickness and composition of the silicon carbide film of the second thickness 502. Therefore, the deposition time, pressure, temperature, RF power, gas flow, and gas composition used to deposit the silicon carbide film of the second thickness 502 can be the same as or different from the deposition time, pressure, temperature, RF power, gas flow, and gas composition used to deposit the silicon carbide film of the first thickness 501.

[0099] Figure 5D Shows Figure 5C501. A cross-section of a silicon carbide film densified by remote plasma treatment. After depositing a second thickness 502 of silicon carbide film on the first thickness 501, the second thickness 502 is exposed to a remote plasma treatment 520 to densify at least the second thickness 502. The operation of exposing the second thickness 502 to the remote plasma treatment 520 can be the same as or at least similar to the operation of exposing the first thickness 501 to the remote plasma treatment 510. In other words, the process of exposing the second thickness 502 to the remote plasma treatment 520 can repeat the process of exposing the first thickness 501 to the remote plasma treatment 510. For example, if exposing the first thickness 501 to the remote plasma treatment 510 includes: flowing a source gas into a remote plasma source, generating radicals of the source gas from the source gas in the remote plasma source, and flowing the radicals of the source gas to the first thickness 501 of the silicon carbide film, then exposing the second thickness 502 to the remote plasma treatment 520 includes repeating the above operations on the second thickness 502 of the silicon carbide film. In some embodiments, the treatment times are the same. In some embodiments, the treatment times are different. The processing time may be sufficient to allow the remote plasma to penetrate the silicon carbide film of the second thickness 502. Different processing times may result in the silicon carbide film having a density gradient throughout the thickness of the film. In addition, controlling the processing time and various process conditions (such as pressure, RF power, gas flow rate, and gas composition) may change the processing efficiency and densification of the silicon carbide film of the second thickness 502. Therefore, the processing time, pressure, RF power, gas flow rate, and gas composition of the remote plasma processing 520 may be the same as or different from the processing time, pressure, RF power, gas flow rate, and gas composition used for the remote plasma processing 510.

[0100] refer to Figures 5A-5D , deposition and densification of doped or undoped silicon carbide films can be achieved by alternating deposition and treatment cycles. Deposition and densification are performed in a layer-by-layer manner so that each remote plasma treatment cycle can fully densify the deposited layer. In this way, the entire film stack can be densified and have a more uniform film density throughout the thickness of the film stack. Therefore, it should be understood that the deposition and treatment cycles for forming silicon carbide films are not limited to Figures 5A-5D The operation shown in FIG. 1 can be repeated until the desired film thickness is reached. The densified silicon carbide film disclosed herein can be implemented in a variety of applications, including in Figure 1B-1D , which is discussed in further detail below.

[0101] Densifying the silicon carbide film using a layer-by-layer approach can produce a greater overall bond density than when the silicon carbide film is not densified in a layer-by-layer approach. Remote plasma treatment can densify the silicon carbide film by removing hydrogen atoms from Si-CH3, Si-OH and / or Si-H groups and promote crosslinking in the chemical structure of the silicon carbide film. Remote plasma treatment can densify the silicon carbide film by increasing the bond density of Si-C bonds and reducing the number of terminal CH3 bonds and Si-H bonds. In some embodiments involving oxygen-doped silicon carbide films, remote plasma treatment can densify the oxygen-doped silicon carbide film by increasing the bond density of Si-C and Si-O bonds and reducing the number of terminal CH3 bonds, Si-OH bonds, and Si-H bonds.

[0102] The process conditions for forming a densified silicon carbide film can provide a highly conformal film structure. Relatively mild process conditions during deposition and processing can minimize the degree of ion bombardment at the substrate surface so that deposition and processing are isotropic. In addition, relatively mild process conditions can reduce the number of free radicals with a high adhesion coefficient, which have a tendency to adhere to the sidewalls of previously deposited layers or films. In certain embodiments, for a depth-to-width ratio of about 2:1 to 10:1, the densified silicon carbide film can be deposited at a conformality rate between about 25% and 100%, more typically between about 50% and 100%, and even more typically between about 80% and 100%. The conformality rate 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 rate 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 embodiments where densified silicon carbide is formed on features having an aspect ratio between about 2:1 and about 4:1, the conformality is at least about 90%. Certain BEOL (back end of line) processes fall into this category. In some embodiments where densified silicon carbide is formed on features having an aspect ratio between about 4:1 and about 6:1, the conformality is at least about 80%. Certain pad deposition processes fall into this category. In some embodiments where densified silicon carbide is formed on features having an aspect ratio between about 7:1 and about 10:1 (or even higher), the conformality is at least about 90%. Certain DRAM manufacturing processes fall into this category.

[0103] The process conditions for forming the densified silicon carbide film can also provide a film structure with high breakdown voltage and low leakage current. In some embodiments, introducing a limited amount of oxygen or nitrogen into the silicon carbide material will cause the leakage path provided by the Si-H bond and / or Si-CH2-Si bond to be blocked by oxygen or nitrogen. The conduction mode can be different in Si-O and Si-N under low field. Remote plasma treatment can provide improved electrical properties while maintaining a relatively low dielectric constant. In various embodiments, the film has an effective dielectric constant of about 6.0 or lower, or about 5.0 or lower, or about 4.0 or lower, and about 3.5 or lower in some cases, and about 3.0 or lower in some cases, and about 2.5 or lower in other embodiments. The effective dielectric constant can depend on bonding and density.

[0104] Fig. 6A Fourier transform infrared spectroscopy (FTIR) absorption spectra are shown with various vibrational peaks used to detect certain bonding types in delaminated and untreated silicon carbide films. Figure 6B-6E Shows Fig. 6A A magnified view of the various vibrational peaks of the FTIR absorption spectrum used to detect certain bonding types in the delaminated and untreated SiC films. The delaminated and untreated SiC films have the same thickness. Figure 6B An increase in Si-O and Si-C peaks is shown for silicon carbide films processed in a layer-by-layer method. Higher peaks correspond to more Si-O and Si-C bonds per unit volume. Without being bound by any theory, the increase in bond density of Si-C bonds may be caused by cross-linking of Si-CH3 groups. The increase in bond density of Si-O bonds may be caused by cross-linking of Si-OH groups.

[0105] Remote plasma treatment with layered operation can improve the properties of silicon carbide films. For example, the layered silicon carbide film can exhibit a greater dry etching selectivity than oxide / nitride. The layered silicon carbide film can also exhibit higher thermal stability and chemical stability. In addition, the layered silicon carbide film can exhibit improved oxygen plasma ash resistance. Table 1 shows the amount of silicon carbide film removed during the oxygen plasma ashing process for removing photoresist before the hydrogen fluoride (HF) wet etching process for removing SiO2. Specifically, the silicon carbide film is exposed to 30 seconds of O2 plasma treatment at 400°C and immersed in an HF bath for 10 minutes. In Table 1, X can be a value between about 10 seconds and about 200 seconds, and Y can be a value between about 5 seconds and about 50 seconds. The results of Table 1 show that the amount of film loss in the center of the silicon carbide film decreases as the processing time of each processing cycle is extended. In addition, the amount of film loss in the center of the silicon carbide film decreases as the deposition time of each deposition cycle is shortened. Therefore, thinner layers per deposition cycle improve the etch resistance and chemical stability of the processed silicon carbide film.

[0106] Table 1

[0107]

[0108]

[0109] Device

[0110] 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.

[0111] Figure 3A schematic diagram of a remote plasma device according to certain embodiments is shown. The device 300 includes a reaction chamber 310 having a showerhead assembly 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 controlling the deposition time in a deposition cycle and the processing time in a processing cycle. In addition, the controller 340 may include instructions for adjusting the pressure, RF power, gas flow, and gas composition of a deposition cycle or a processing cycle.

[0112] 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.

[0113] One or more free radical species may be generated in a remote plasma source 360 ​​and configured to enter the reaction chamber 310 via a 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.

[0114] 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.

[0115] 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.

[0116] In some embodiments, a co-reactant that is not a primary silicon-containing precursor or hydrogen radical is introduced during a deposition cycle or a treatment cycle. In some embodiments, the apparatus is configured to introduce the co-reactant through the second gas inlet 365, in which case the co-reactant is at least partially converted into plasma. In some embodiments, the apparatus is configured to introduce the co-reactant through the showerhead 320 via the first gas inlet 355. Examples of co-reactants include oxygen, nitrogen, ammonia, carbon dioxide, carbon monoxide, and the like.

[0117] The controller 340 may contain instructions for controlling process conditions for the operation of the apparatus 300. The controller 340 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. The instructions for implementing the appropriate control operations are executed on the processor. These instructions may be stored in a memory device associated with the controller 340, or they may be provided over a network.

[0118] In certain embodiments, the controller 340 controls all or most of the actions of the semiconductor processing device 300 described herein. For example, the controller 340 may control all or most of the actions of the semiconductor processing device 300 associated with depositing a silicon carbide film and processing the silicon carbide film to densify the silicon carbide film. The controller 340 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 340 may be used in some embodiments. In order to provide relatively mild reaction conditions in the environment adjacent to the substrate 330, parameters such as RF power level, gas flow rate flowing to the remote plasma region, and timing of plasma ignition may be adjusted and maintained by the controller 340. In addition, adjusting the substrate position may further reduce the presence of high-energy radical species in the environment adjacent to the substrate 330. In a multi-station reactor, the controller 340 may include different or identical instructions for different device stations, so that the device stations can operate independently or synchronously.

[0119] In some embodiments, the controller 340 may include instructions for performing operations such as providing a substrate 330 in the reaction chamber 310, depositing a silicon carbide film of a first thickness on the substrate 330, exposing the silicon carbide film of the first thickness to a remote hydrogen plasma treatment, depositing a silicon carbide film of a second thickness on the silicon carbide film of the first thickness, and exposing the silicon carbide film of the second thickness to the remote hydrogen plasma treatment. In some embodiments, exposing the silicon carbide film of the first thickness and the silicon carbide film of the second thickness to the remote hydrogen plasma treatment includes flowing one or more hydrogen radicals in a substantially low energy state from the remote plasma source 360.

[0120] In some embodiments, the apparatus may include a user interface associated with the controller 340. The user interface may include a display screen, a graphical software display of apparatus and / or process conditions, and a user input device such as a pointing device, a keyboard, a touch screen, a microphone, and the like.

[0121] 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.

[0122] 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.

[0123] 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, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, processing time, deposition time, wafer transfer in and out of tools and other transfer tools and / or load locks connected to or connected to a specific system through an interface.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] application

[0130] The present disclosure may be further understood by reference to the following applications for high quality silicon carbide films, including densified silicon carbide films, wherein the applications are meant purely as examples. The present invention is not limited in scope by the specific applications, which are merely brief illustrations of aspects of the present disclosure.

[0131] In some embodiments, a silicon carbide film can be deposited on exposed copper. During the deposition of the 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 the silicon carbide film can provide a sufficiently low dielectric constant with excellent leakage characteristics to serve as a diffusion barrier. The silicon carbide film itself or as a double-layer stack (for example, a silicon carbide / SiCN double layer deposited on exposed copper) or as a gradient film (for example, a gradient SiCO film) or a multi-layer stack (for example, a multi-layer SiCO film) can be an etch stop and / or diffusion barrier. In some embodiments, the silicon carbide film can be placed between adjacent metallization layers that are typically produced by a damascene process. The silicon carbide film is resistant to etching and can be dense enough to minimize the diffusion of copper ions into adjacent areas of the dielectric material. In some embodiments, the precursor used for the silicon carbide film can be non-cyclic. The non-cyclic precursor can include PMDSO or TMDSO. The non-cyclic precursor can provide a sufficiently high density to act as a seal or diffusion barrier. In some embodiments, nitrogen can be incorporated into the film by using a nitrogen-containing precursor or plasma-activated nitrogen-containing radicals (such as elemental nitrogen radicals or amine radicals).

[0132] 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. Figure 1B 1 shows a cross section of a silicon carbide liner deposited on the sidewalls of a gate electrode structure of a transistor. Figure 1B As shown in , the transistor may be a CMOS transistor having a silicon substrate 110 having a source 112 and a drain 113. A gate dielectric 114 may be deposited on the silicon substrate 110, and a gate electrode 115 may be deposited on the gate dielectric to form the transistor. A silicon carbide liner 111 may be deposited on the sidewalls of the gate electrode 115 and the gate dielectric 114. In another example, Figure 1CA cross section of silicon carbide deposited on the sidewalls of exposed copper lines in an air gap type metallization layer is shown. Air gaps 120 can be introduced into an integrated circuit layer between copper lines 122, thereby reducing the effective k value of the layer. Silicon carbide liner 121 can be deposited on the sidewalls of copper lines 122, and a non-conformal dielectric layer 123 can be deposited on air gap 120, liner 121, and copper lines 122. Examples of such air gap type metallization layers can be described in U.S. Patent Publication No. 2004 / 0232552 to Fei Wang et al., which is incorporated herein by reference in its entirety and for all purposes.

[0133] 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. Figure 1D A cross section of silicon carbide as a hole sealant for a porous dielectric material is shown. The porous dielectric layer 132 may have a plurality of grooves or through holes cut into the porous dielectric layer 132 to form holes 130. Silicon carbide 131 may be deposited along the holes 130 to effectively seal the holes 130. Sealing the holes 130 with silicon carbide 131 may avoid damage to the porous dielectric layer 132 that would otherwise be caused by other sealing techniques using plasma. Silicon carbide 131 may be sufficiently dense as a hole sealant and may include non-cyclic silicon-containing precursors such as PMDSO and TMDSO. In some embodiments, the etched dielectric material, such as the porous dielectric layer 132, may first be treated by a "k-recovery" process, which exposes the porous dielectric layer 132 to UV radiation and a reducing agent. The restoration process is further described in co-owned U.S. Patent 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 132 can be exposed to UV radiation and a chemical silylating agent. The restoration process is further described in co-owned U.S. Patent Publication No. 2011 / 0117678 to Varadarajan et al., which is incorporated herein by reference in its entirety and for all purposes. After the pores 130 are exposed to the restoration treatment, thereby making the surface more hydrophilic and providing a monolayer of material, a conformally deposited layer of silicon carbide 131 can be deposited to effectively seal the pores of the porous dielectric layer 132.

[0134] 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.

[0135] Although some of the above details have been described for the purpose of clarity and understanding, it is apparent that certain changes and modifications may be implemented within the scope of the appended claims. It should be noted that there are many alternative ways to implement the described processes, systems, and devices. Therefore, the described embodiments should be considered illustrative rather than restrictive.

Claims

1. A method for depositing a doped silicon carbide film, the method comprising: flowing one or more silicon-containing precursors into a reaction chamber, wherein each of the one or more silicon-containing precursors comprises Si-H bonds and / or Si-Si bonds, and Si-C bonds, Si-O bonds, and / or Si-N bonds; and Radicals of a source gas generated from a remote plasma source are flowed into the reaction chamber, wherein the radicals are in a substantially low energy state or ground state in an environment adjacent to a substrate in the reaction chamber, wherein the radicals react with the one or more silicon-containing precursors in the environment adjacent to the substrate to deposit a doped silicon carbide film having a high breakdown voltage and a low leakage current on the substrate.

2. The method of claim 1, further comprising: before the free radicals of the source gas flow into the reaction chamber, flowing the source gas into the remote plasma source located upstream of the reaction chamber; and Radicals of the source gas are generated in the remote plasma source, wherein the remote plasma source is configured such that a residence time of the radicals from the remote plasma source to the environment adjacent to the substrate is greater than an energy release time of the radicals of the source gas. 3 . The method of claim 1 , wherein the source gas comprises hydrogen, nitrogen, or a gas containing an NH bond. The method of claim 1 , wherein the radicals of the source gas include hydrogen atom radicals.

5. The method of claim 4, wherein a substantial portion of the hydrogen atom radicals are hydrogen atom radicals in a ground state in the environment adjacent to the substrate.

6. The method of claim 1, wherein a concentration of dopant atoms in the doped silicon carbide film is at least 50% atomic, wherein the dopant atoms include one or both of oxygen (O) atoms and nitrogen (N) atoms. 7 . The method of claim 1 , wherein the one or more silicon-containing precursors include a first silicon-containing precursor having Si—O bonds and Si—N bonds and a second silicon-containing precursor having Si—C bonds.

8. The method of claim 1, further comprising: The doped silicon carbide film is densified by exposing the doped silicon carbide film to a remote hydrogen plasma in the reaction chamber.

9. The method of claim 8, wherein densifying the doped silicon carbide film reduces terminal CH3 groups, reduces Si-H bonds, and increases cross-linking in the doped silicon carbide film.

10. The method of claim 8, wherein densifying the doped silicon carbide film reduces etch rate, increases etch selectivity to silicon oxide, increases oxygen plasma ashing resistance, and increases thermal stability of the doped silicon carbide film.

11. A method for depositing a silicon carbide film, the method comprising: (a) flowing one or more silicon-containing precursors into a reaction chamber; (b) flowing a co-reactant into the reaction chamber simultaneously with the one or more silicon-containing precursors, wherein the co-reactant comprises carbon dioxide, carbon monoxide, water, methanol, oxygen, ozone, nitrogen, nitrous oxide, ammonia, methane, diazene, methane, ethane, propane, acetylene, ethylene, diborane, or a combination thereof; (c) generating a remote hydrogen plasma in a remote plasma source located upstream of the reaction chamber; and (d) exposing the one or more silicon-containing precursors and the co-reactant to the remote hydrogen plasma in an environment adjacent to a substrate to deposit a first layer of a silicon carbide film on the substrate.

12. The method of claim 11, wherein each of the one or more silicon-containing precursors comprises an alkyl group.

13. The method of claim 11, wherein the one or more silicon-containing precursors comprise an alkylsilane, wherein the alkylsilane comprises pentamethyldisilane.

14. The method of claim 11, further comprising: An inert carrier gas is flowed into the reaction chamber simultaneously with the one or more silicon-containing precursors and the co-reactant.

15. The method of claim 11, wherein the one or more silicon-containing precursors comprises a plurality of silicon-containing precursors, wherein the plurality of silicon-containing precursors comprises a siloxane and an alkylsilane.

16. The method of claim 11, wherein the co-reactant flows through the same flow path as the remote hydrogen plasma such that the co-reactant is radicalized or ionized.

17. The method of claim 11, further comprising: The first layer of the silicon carbide film is densified by exposing the first layer of the silicon carbide film to a first remote hydrogen plasma treatment in the reaction chamber.

18. The method of claim 17, further comprising: Depositing a second layer of the silicon carbide film on the substrate by repeating operations (a)-(d) in the reaction chamber; and The second layer of the silicon carbide film is densified by exposing the second layer of the silicon carbide film to a second remote hydrogen plasma treatment in the reaction chamber.

19. A method for depositing a silicon carbide film, the method comprising: flowing a plurality of silicon-containing precursors including a major species and a minor species into a reaction chamber; flowing a non-hydrogen co-reactant and a plurality of silicon-containing precursors simultaneously into the reaction chamber; and Hydrogen atomic radicals generated in a remote plasma source are flowed into the reaction chamber, wherein the hydrogen atomic radicals react with the non-hydrogen co-reactant and the plurality of silicon-containing precursors in an environment adjacent to a substrate to deposit a silicon carbide film on the substrate.

20. The method of claim 19, wherein the non-hydrogen co-reactant flows through the same flow path as the remote hydrogen plasma such that the non-hydrogen co-reactant is radicalized or ionized.

21. The method of claim 19, wherein the non-hydrogen co-reactant flows through the same flow path as the plurality of silicon-containing precursors such that the non-hydrogen co-reactant is not exposed to a plasma.

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