KR20220034758A - Remote plasma based deposition of oxygen doped silicon carbide films - Google Patents

Abstract

A device (300) for depositing oxygen doped silicon carbide (SiOC) films on a substrate (330) includes a reaction chamber (310) including a pedestal (334) to support the substrate (330); a vessel (350) configured to supply silicon-containing precursors into the reaction chamber (310) through a first gas inlet (355); a plasma source (360) separated from the reaction chamber (310); a means for controlling the plasma source (360) to produce, from a source gas, hydrogen radicals in the plasma source (360); a second gas inlet (365) for introducing the hydrogen radicals from the plasma source (360) into the reaction chamber (310); and a controller (340).

Description

REMOTE PLASMA BASED DEPOSITION OF OXYGEN DOPED SILICON CARBIDE FILMS

The present disclosure relates generally to the formation of oxygen doped silicon carbide films.

Thin films of the silicon carbide (SiC) class have intrinsic physical, chemical and mechanical properties and are used in various applications, especially integrated circuit applications. One of these SiC-like thin films contains oxygen-doped SiC.

The present disclosure relates to a method of depositing an oxygen doped silicon carbide (SiCO) film. The method includes providing a substrate, and flowing one or more silicon-comprising precursors onto the substrate, wherein each of the one or more silicon-comprising precursors comprises (i) one or more silicon-hydrogen bonds and/or silicon-silicon bonds. and (ii) one or more silicon-oxygen bonds and one or more silicon-carbon bonds. The method includes flowing a source gas into a remote plasma source, generating hydrogen radicals from the source gas in the remote plasma source, and introducing the hydrogen radicals onto a substrate, wherein at least 90% of the radicals are silicon - substantially react with one or more silicon containing precursors to form a SiCO film on the substrate under conditions that break one or both of the hydrogen bonds and silicon-silicon bonds but preserve the silicon-oxygen bonds and silicon-carbon bonds Hydrogen radicals in a low energy state.

In some embodiments, silicon-comprising precursors include cyclic siloxanes. In some embodiments, silicon comprising precursors comprise alkoxy silanes. In some implementations, the radicals are generated from a hydrogen source gas. In some implementations, the ratio of silicon-oxygen bonds to silicon-carbon bonds in the SiCO film is from about 0.5:1 to about 3:1. In some implementations, the SiCO film comprises a conformal thin film on the substrate. In some implementations, the substrate includes a transistor having a gate electrode, and the method further includes forming a SiCO film on one or more sidewalls of the gate electrode.

The present disclosure also relates to an apparatus for depositing an oxygen-doped silicon carbide film on a substrate. The apparatus includes a reaction chamber including a substrate support for supporting a substrate, a remote plasma source coupled to the reaction chamber and configured to generate a plasma outside the reaction chamber, one or more gas inlets coupled to the reaction chamber, and operation of: s: (a) flowing one or more silicon-comprising precursors onto a substrate, each of the one or more silicon-comprising precursors comprising (i) one or more silicon-hydrogen bonds and/or silicon-silicon bonds and (ii) one or more silicon-containing precursors; flowing one or more silicon comprising precursors onto a substrate having silicon-oxygen bonds and one or more silicon-carbon bonds, (b) flowing a source gas into a remote plasma source, (c) a source gas in the remote plasma source generating hydrogen radicals from and (d) introducing hydrogen radicals onto the substrate, wherein at least 90% of the radicals break one or both of silicon-hydrogen bonds and silicon-silicon bonds, but silicon- Oxygen bonds and silicon-carbon bonds perform the operation of introducing hydrogen radicals onto the substrate, which are hydrogen radicals in a substantially low energy state that react with one or more silicon-comprising precursors to form a SiCO film on the substrate under conditions that preserve it. and a controller including instructions for doing so.

In some embodiments, silicon-comprising precursors include cyclic siloxanes. In some embodiments, silicon comprising precursors comprise alkoxy silanes. In some implementations, the radicals are generated from a hydrogen source gas. In some implementations, the ratio of silicon-oxygen bonds to silicon-carbon bonds in the SiCO film is from about 0.5:1 to about 3:1. In some implementations, the SiCO film comprises a conformal thin film on the substrate. In some implementations, the substrate includes a transistor having a gate electrode, and the controller further includes instructions for forming a SiCO film on one or more sidewalls of the gate electrode.

1A illustrates a cross-section of an example of an oxygen doped silicon carbide film deposited over a substrate.
1B illustrates oxygen doped silicon carbide vertical structures on sidewalls of a gate electrode structure of a transistor.
1C illustrates oxygen doped silicon carbide vertical structures on exposed sidewalls of copper lines of an air gap type metallization layer.
1D illustrates oxygen doped silicon carbide pore sealants for porous dielectric materials.
1E illustrates a three-dimensional schematic diagram of an example integration flow for fabricating fin field-effect transistor (finFET) structures.
2 illustrates examples of representative caged siloxane precursors.
3 illustrates a schematic diagram of a processing apparatus having a remote plasma source.
4A illustrates the chemical structure of an exemplary conventional silicon oxycarbide or carbon doped silicon oxide (SiOC or SiOC:H).
4B illustrates the chemical structure of an exemplary oxygen doped silicon carbide (SiCO).
5A illustrates a Fourier Transform Infrared Spectroscopy (FTIR) plot of the chemical stability of an exemplary conventional silicon oxycarbide or carbon doped silicon oxide (SiOC or SiOC:H).
5B illustrates a thermal desorption spectroscopy (TDS) plot of the thermal stability of an exemplary conventional silicon oxycarbide or carbon doped silicon oxide (SiOC or SiOC:H).
6A illustrates an FTIR plot of the chemical stability of an exemplary oxygen doped silicon carbide (SiCO).
6B illustrates a TDS plot of an exemplary oxygen doped silicon carbide (SiCO).

In the following description, numerous specific details are set forth in order 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 instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the concepts presented. While some concepts are described with respect to specific embodiments, it will be understood that they are not intended to limit these embodiments.

In this application, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially fabricated integrated circuit" will be used interchangeably. Those skilled in the art will understand that the term “partially fabricated integrated circuit” may refer to a silicon wafer during any of the many stages of integrated circuit fabrication thereon. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. The detailed description below assumes that the invention is implemented on a wafer. However, the present invention is not so limited. The workpiece may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that may benefit from the present invention include various articles such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micro-mechanical devices, and the like. include

introduction

Fabrication of semiconductor devices typically involves depositing one or more thin films on a substrate in an integrated manufacturing process. In aspects of the manufacturing process, thin films of classes such as SiC and SiCN use atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or any other suitable deposition method. is deposited by

Another class of thin films that can be deposited includes silicon oxycarbide (SiOC). Conventional SiOC films are typically formed by doping carbon into silicon oxide. Silicon containing precursors may be delivered together with carbon containing precursors such as methane, carbon dioxide, or carbon monoxide. A silicon oxide film comprising carbon may be formed using a suitable deposition process. In some implementations, precursor molecules for depositing SiOC are silicon-hydrogen (Si-H) bonds, silicon-silicon (Si-Si) bonds, silicon-carbon (Si-C) bonds, and/or silicon-containing molecules having silicon-oxygen (Si-O) bonds. Current PECVD processes may use in situ plasma processing in which plasma is provided directly adjacent to the processed substrate.

Depositing high quality SiOC thin films can produce films with excellent step coverage, low dielectric constants, high breakdown voltages, low leakage currents, high porosity, and/or coverage over metal surfaces that do not oxidize exposed metal surfaces. It can be seen that there may be specific challenges such as providing.

While this disclosure is not limited to any particular theory, it is believed that the plasma conditions of conventional PECVD processes fragment silicon containing precursor molecules in a manner that creates undesirable effects. For example, PECVD may break Si-O and/or Si-C bonds in precursor molecules to create highly reactive radicals or other fragment types with high adhesion coefficients. The fragments and the resulting SiOC film may contain silicon, carbon, and/or oxygen atoms that are "dangling" bonding, meaning that the silicon, carbon, and/or oxygen atoms have valence electrons that are not reactively paired. there is. The high adhesion coefficients of the precursor molecules and their fragments will not deposit SiOC films with poor step coverage, as the reactive precursor fragments may adhere disproportionately to the upper regions of the sidewalls and other structures of the recessed features. can Dangling bonds can create silanol groups (Si—OH) in the deposited SiOC film. As a result, the film may have uselessly high dielectric constants. Film quality may also deteriorate because direct plasma conditions tend to extract carbon from the deposited film.

In addition, dangling bonds can create increased silicon-hydrogen bonding (Si-H) in the deposited SiOC films. Broken bonds of Si-C can displace Si-H in direct plasma deposition conditions. The presence of Si-H bonds in SiOC films can produce films with poor electrical properties. For example, the presence of Si-H bonds can reduce breakdown voltages and increase leakage current because Si-H bonds can provide a leakage current of electrons.

Also, dangling bonds can lead to uncontrolled chemical or morphological structures in SiOC films. In some cases, these structures are dense filaments with low porosity or no porosity, such that the film has an unacceptably high dielectric constant. The lack of porosity may be the result of direct plasma conditions that break the Si-C and/or Si-O bonds of the cyclic siloxanes, otherwise providing porosity to the ultra-low-k dielectric material.

The direct plasma conditions employed in PECVD can sometimes cause directivity in deposition, as the energy to break up precursor molecules can be at a low frequency that creates most of the ion bombardment at the surface. Directed deposition can also lead to deposition of SiOC films with poor step coverage. A direct plasma is a plasma (adequate concentration of electrons and positive ions) that resides in close proximity to the substrate surface during deposition, and is sometimes separated from the substrate surface only by a plasma sheath.

Conventional PECVD processes are sometimes unsuitable for depositing SiOC films over exposed copper or other metal surfaces because these processes can oxidize the metal. The PECVD process may use an oxidizing agent such as oxygen (O ₂ ), ozone (O ₃ ), carbon dioxide (CO ₂ ), carbon monoxide (CO), or other oxidizing species to form SiOC.

Atmosphere of the substrate surface during deposition

1A illustrates a cross-section of an example of an oxygen doped silicon carbide film deposited over a substrate. The oxygen-doped silicon carbide film 101 can be formed under process conditions and can create a relatively weak atmosphere adjacent to the substrate 100 . Substrate 100 may be any wafer, semiconductor wafer, partially fabricated integrated circuit, printed circuit board, display screen, or other suitable workpiece. The process for depositing the oxygen-doped silicon carbide film 101 may include one or more silicon-comprising precursors having one or more Si-H bonds and/or one or more Si-Si bonds.

Specific applications employing oxygen doped silicon carbide films are shown in FIGS. 1B and 1D . In some embodiments, silicon comprising precursors may comprise silicon-oxygen comprising precursors and/or silicon-carbon comprising precursors. Silicon-oxygen containing precursors may include one or more Si-O bonds, and silicon-carbon containing precursors may include one or more Si-C bonds. In some embodiments, for example, silicon comprising precursors may comprise a single reactant A having Si-O and Si-C bonds. In some embodiments, silicon-comprising precursors may include reactant B having Si-O bonds and reactant C having Si-C bonds. It will be understood that any number of suitable reactants may be employed within the scope of the present disclosure. Chemical structures of exemplary silicon-comprising precursors are discussed in greater detail below.

Silicon comprising precursors include one or more Si-H bonds and/or one or more Si-Si bonds. During the deposition process, Si-H bonds and/or Si-Si bonds will be broken and will serve as reaction sites for forming bonds between silicon-containing precursors of the deposited oxygen doped silicon carbide film 101 . will be. Broken bonds can also serve as sites for crosslinking during or after deposition, during thermal processing performed. The bonding and crosslinking at the reaction sites may collectively form a matrix or main backbone within the resulting oxygen doped silicon carbide film 101 .

In some embodiments, the process conditions may preserve, or at least substantially preserve, Si-O and Si-C bonds in the layer as deposited of the oxygen doped silicon carbide film 101 . Accordingly, the reaction conditions adjacent to the substrate 100 provide for breaking of Si-H and/or Si-Si bonds, eg, extraction of hydrogen from the broken Si-H bonds, while the reaction conditions are not Si-O It does not provide oxygen from bonds or carbon extraction from Si-C bonds. In general, the reaction conditions described are present on the exposed side of the substrate (the side on which the oxygen-doped silicon carbide film is deposited). These conditions may further exist at some distance above the workpiece, for example, from about 0.5 μm to about 150 mm above the workpiece. Indeed, activation of the precursor can occur in the gaseous phase at considerable distances above the workpiece. Typically, suitable reaction conditions will be uniform or substantially uniform over the entire exposed side of the substrate, although certain applications may allow for some variations.

In addition to silicon-comprising precursors, the atmosphere adjacent the workpiece may include one or more radical species, preferably in a substantially low energy state. Examples of such species include hydrogen atom radicals. In some embodiments, all, or substantially all, or a significant fraction of the hydrogen atom radicals may be in the ground state, eg, at least about 90% or 95% of the hydrogen atom radicals adjacent to the workpiece is in the ground state. In certain embodiments, hydrogen is provided in a carrier such as helium. As an example, hydrogen gas may be provided to the helium carrier at a hydrogen concentration of about 1 to 10%. The pressure, fraction of a carrier gas such as helium, and other process conditions are chosen so that the hydrogen atoms face the substrate when the radicals in the low energy state do not recombine.

As described elsewhere, hydrogen gas may be supplied into the remote plasma source to generate hydrogen radicals. Once generated, the hydrogen radicals may 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 radicals may cause non-selective decomposition of the silicon containing precursor. For example, hydrogen radicals in an excited state can readily break Si-H, Si-Si, Si-O, and Si-C bonds, which can change the composition or physical or electrical properties of the silicon carbide film. In some embodiments, when excited hydrogen radicals lose energy, or are relaxed, the excited hydrogen radical may become substantially a low energy state hydrogen radical or a ground state hydrogen radical. Substantially low energy state or ground state hydrogen radicals can selectively break Si-H and Si-Si bonds, while generally preserving Si-O and Si-C bonds. In some implementations, process conditions may be provided such that the excited hydrogen radicals substantially lose energy or relax to form low energy state or ground state hydrogen radicals. For example, the remote plasma source or associated components may be designed such that the residence time of hydrogen radicals diffusing from the remote plasma source to the substrate is greater than the energetic relaxation time of the excited hydrogen radical. The energetic relaxation time for the excited hydrogen radical may be approximately equal to or less than 1x10 ^-3 seconds.

A state in which a significant fraction of hydrogen atom radicals are in the ground state can be achieved by various techniques. Some devices as described below are designed to achieve this state. Device features and process control features can be tested and tuned to create a weak state in which a significant fraction of hydrogen atom radicals are in the ground state. For example, the apparatus may be downstream of a plasma source; That is, it may operate and be tested on charged particles in the vicinity of the substrate. The process and apparatus may be tuned until there is substantially no charged paper in the vicinity of the substrate. Additionally, the apparatus and process features may be tuned to a configuration starting with producing high quality silicon carbide films from standard precursors such as trimethylsilane. Relatively weak conditions that support such film deposition are selected.

Other examples of radical species include nitrogen containing species such as elemental nitrogen radicals (atomic or diatomic) and N—H containing radicals such as ammonia radicals, wherein nitrogen is optionally incorporated into the film. Examples of N-H containing radicals include, but are not limited to, methylamine, dimethylamine, and aniline. The aforementioned radical species may be generated from gases comprising hydrogen, nitrogen, N—H comprising species, or mixtures thereof. In some embodiments, essentially all atoms of the deposited film are provided by precursor molecules. In such cases, the low energy radicals used to drive the deposition reaction may be exclusively hydrogen or a species that does not substantially contribute to the mass of the deposited layer. In some embodiments, as discussed in more detail below, the radical species may be generated by a remote plasma source. In some embodiments, higher energy state radicals or even ions may potentially be present near the wafer plane.

In some embodiments, the process conditions break Si-H bonds and/or Si-Si bonds, but generate radical species in a substantially low energy state sufficient to preserve or substantially preserve Si-O and Si-C bonds. hire Such process conditions may not have significant amounts of ions, electrons, or radical species of high energy states, such as those above the ground state. In some embodiments, the concentration of ions in the region adjacent to the film is less than or equal to about 10 ⁷ /cm 3 . The presence of significant amounts of ions or high-energy radicals may tend to break Si-O or Si-C bonds, leading to undesirable electrical properties (eg, high dielectric constants and/or low breakdown voltage). ) and films with poor conformality. It is believed that an overly reactive atmosphere produces reactive precursor fragments with high adhesion modulus (indicating a tendency to chemically or physically adhere to workpiece sidewalls), resulting in poor conformality.

Silicon-comprising precursors are delivered together with another species, particularly a carrier gas, typically in an atmosphere adjacent to the substrate 100 . In some embodiments, silicon-comprising precursors are present with radical species and other species, including other reactive species and/or carrier gases. In some embodiments, silicon comprising precursors may be introduced as a mixture. Upstream from the deposition reaction surface, silicon-comprising precursors may be mixed with an inert carrier gas. Exemplary inert carrier gases include, but are not limited to, nitrogen (N ₂ ), argon (Ar), and helium (He). In addition, silicon containing precursors may be introduced as a mixture having a major and minor species, the minor species being present in the oxygen doped silicon carbide film 101 at a relatively low concentration. Some elements or structural features (eg, ring structures, cage structures, unsaturated bonds, etc.). A plurality of precursors may be present in equimolar or relatively similar proportions as appropriate to form the primary backbone or matrix of the oxygen-doped silicon carbide film 101 generated. In other embodiments, the relative amounts of different precursors are substantially distorted from equimolarity.

In some embodiments, the one or more silicon comprising precursors provide essentially the total weight of the deposited silicon carbide film with a small amount of hydrogen or other element from a remote plasma providing less than about 5 atomic percent or about 2 atomic percent of the film mass. do. In some embodiments, only the radical species and one or more silicon containing precursors contribute to the composition of the deposited silicon carbide film. In other embodiments, the deposition reaction includes one or more silicon-comprising precursors and a radical species and other co-reactant. Examples of such co-reactants include carbon dioxide (CO ₂ ), carbon monoxide (CO), water (H ₂ O), methanol (CH ₃ OH), oxygen (O ₂ ), ozone (O ₃ ), nitrogen (N ₂ ), nitrous oxide (N ₂ O), ammonia (NH ₃ ), methane (CH ₄ ), ethane (C ₂ H ₆ ), acetylene (C ₂ H ₂ ), ethylene (C ₂ H ₄ ), diborane, and combinations thereof include those These materials may be used as nitriding agents, oxidizing agents, reducing agents, and the like. In some cases, they can be used to tune the amount of carbon in the deposited film by removing a fraction of the carbon provided with the silicon containing precursor. In some embodiments employing a non-hydrogen co-reactant, the co-reactant is introduced into the reactor through the same flow path as the silicon-comprising precursor, eg, through a path comprising a showerhead, typically without direct exposure to plasma. . In some embodiments, oxygen and/or carbon dioxide is introduced along with the precursor to alter the composition of the silicon carbide film by removing carbon from the film or precursor during deposition. In some embodiments employing a non-hydrogen co-reactant, the co-reactant is introduced into the reactor via the same flow path as the hydrogen, such that the co-reactant is at least partially converted to radicals and/or ions. In such embodiments, both the hydrogen radicals and the co-reactant radicals react with the silicon-comprising precursor(s) to produce a deposited silicon carbide film.

In certain embodiments where the co-reactants are used and introduced into the chamber with a species (eg, hydrogen) that is converted to radicals, the co-reactants include a source of radicals (eg, hydrogen) in the reactor It is provided along with any carrier gas(s), such as helium, into the reactor in a relatively small amount compared to the other gases in it. For example, the co-reactant may be present in the process gases up to about 0.05 mass percent, or up to about 0.01 mass percent, or up to about 0.001 mass percent. For example, the reactant mixture (entering the plasma source) may be about 10 L/m He, about 200-500 sccm H2, and about 1-5 sccm oxygen. When the co-reactants are introduced into the chamber (eg, via a showerhead) along with the silicon-comprising precursor, they are at higher concentrations; For example, it may be present in about 2% or less or about 0.1% or less. When the co-reactant is a relatively weak reactant (eg, a weak oxidizing agent such as carbon dioxide), it may be present in much higher concentrations, up to about 10% or up to about 4%.

The temperature of the atmosphere adjacent to the substrate 100 may be a suitable temperature to facilitate the deposition reaction, but is sometimes limited to applications of devices including the oxygen-doped silicon carbide film 101 . The temperature of the atmosphere adjacent to the substrate 100 can be largely controlled by the temperature of the pedestal on which the substrate 100 is supported during deposition of the oxygen-doped silicon carbide film 101 . In some embodiments, the operating temperature may be from about 50 °C to about 500 °C. For example, in many integrated circuit applications the operating temperature may be between about 250°C and about 400°C. In some embodiments, an elevated temperature may cause increased crosslinking on the substrate surface.

The pressure of the atmosphere adjacent the substrate 100 can be any pressure suitable to generate reactive radicals within the process chamber. In some embodiments, the pressure may be about 35 Torr or less. For example, as in embodiments implementing a microwave generated plasma, the pressure may be between about 10 Torr and about 20 Torr. In other examples, as in embodiments implementing a radiofrequency (RF) generated plasma, the pressure may be less than about 5 Torr, or between about 0.2 Torr and about 5 Torr.

1B-1E illustrate cross-sections of structures including oxygen doped silicon carbide films in various applications. 1B illustrates oxygen doped silicon carbide vertical structures on sidewalls of a gate electrode structure of a transistor. 1C illustrates oxygen doped silicon carbide vertical structures on exposed sidewalls of copper lines of an air gap type metallization layer. 1D illustrates oxygen doped silicon carbide pore sealants for porous dielectric materials. 1E illustrates oxygen doped silicon carbide spacers through the integration flow of finFET structures. Each of these applications is discussed in more detail below.

Chemical structures of precursors

As discussed, the precursors employed to form the oxygen doped silicon carbide films can be formed of silicon comprising precursors, along with at least some silicon comprising precursors having at least one Si-H bond and/or at least one Si-Si bond. may include In certain embodiments, the silicon-comprising precursor has at most one hydrogen atom on every 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 one or two silicon atoms of the remaining silicon atoms, and the like. In addition, silicon-comprising precursors may include at least one Si-O bond and/or at least one Si-C bond. Any number of suitable precursors may be used to form the oxygen doped silicon carbide films, although at least some precursors include at least one Si-H bond or Si-Si bond, and optionally at least one Si-O bond and/or or silicon-comprising precursors having Si-C bonds. In some embodiments, the silicon-comprising precursor(s) do not include O-C bonds, eg, the precursor(s) do not include alkoxy (-O-R), where R is an organic group such as a hydrocarbon group.

In certain embodiments, at least some of the carbon provided to the oxygen doped silicon carbide film is provided by one or more hydrocarbon moieties on the silicon containing precursor. These moieties may be moieties from alkyl groups, alkene groups, alkyne groups, aryl groups, and the like. In certain embodiments, the hydrocarbon group has a single carbon atom to minimize steric hindrance of the Si-H and/or Si-Si bond breaking reaction during deposition. However, the precursors are not limited to single carbon groups, and a higher number of carbon atoms, such as 2, 3, 4, 5, or 6 carbon atoms, may be used. In certain embodiments, the hydrocarbon group is linear. In certain embodiments, the hydrocarbon group is cyclic.

In some embodiments, silicon containing precursors are divided into one of three or more chemical classes, any class may exist alone as a sole precursor or in combination with other types of precursors. It will be understood that other chemical classes of silicon comprising precursors may be employed and that silicon comprising precursors are not limited to the chemical classes discussed below.

First, the silicon-comprising precursor may be a siloxane. In some embodiments, the siloxane may be cyclic. Cyclic siloxanes may include cyclotetrasiloxanes such as 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane (OMCTS), and heptamethylcyclotetrasiloxane (HMCTS). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. Embodiments using cyclic siloxanes are ring structures that can introduce porosity into an oxygen doped silicon carbide film, with the size of the pores corresponding to the ring radius. For example, the cyclotetrasiloxane ring may have a radius of about 6.7 Angstroms.

In some embodiments, the siloxane may have a three-dimensional or caged structure. 2 illustrates examples of representative caged siloxane precursors. Caged siloxanes have silicon atoms bridged to each other via oxygen atoms to form a polyhedral or arbitrary 3-D structure. An example of a caged siloxane precursor molecule is silsesquioxane. Caged siloxane structures are described in more detail in commonly owned US Pat. No. 6,576,345 to Cleemput et al., which is incorporated herein by reference in its entirety for all purposes. Like cyclic siloxanes, caged siloxanes can introduce porosity into the oxygen doped silicon carbide film. In some embodiments, the porous scale is mesoporous.

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

Second, the silicon-comprising precursor may be an alkyl silane or other hydrocarbon substituted silane. Alkyl silanes contain a central silicon atom and one or more alkyl groups bonded to the silicon atom as well as one or more hydrogen atoms bonded to the silicon atom. In certain embodiments, any one or more alkyl groups contain from 1 to 5 carbon atoms. Hydrocarbon groups may or may not be saturated (eg, alkenes (eg, vinyl), alkynes, and aromatic groups). Examples include, but are not limited to, trimethylsilane (3MS), triethylsilane, pentamethyl disilamethane ((CH ₃ ) ₂ Si—CH ₂ —Si(CH ₃ ) ₃ ), and dimethylsilane (2MS). .

Third, the silicon-comprising precursor may be an alkoxy silane. Alkoxy silanes contain a central silicon atom and one or more alkoxy groups bonded to a silicon atom and one or more hydrogen atoms bonded to a silicon atom. Examples include, but are not limited to, trimethoxysilane (TMOS), dimethoxysilane (DMOS), methoxysilane (MOS), methyldimethoxysilane (MDMOS), diethoxymethylsilane (DEMS), dimethylethoxysilane (DMES), and dimethylmethoxysilane (DMMOS).

Additionally, disilanes, trisilanes, or other higher order silanes may be used in place of monosilanes. In some embodiments, one of the silicon atoms can have a carbon-containing group or a hydrocarbon-containing group attached to the silicon atoms, and one of the silicon atoms can have a hydrogen atom attached to the silicon atom.

In the deposition of oxygen-doped silicon carbide, a plurality of silicon-comprising precursors may be present in the process gas. For example, a siloxane and an alkyl silane may be used together or a siloxane and an alkoxy silane may be used together. The relative proportions of the individual precursors can be selected based on the chemical structures of the selected precursors and the application of the resulting oxygen doped silicon carbide film. For example, the amount of siloxane in mole percentage may be greater than the amount of silane to produce a porous membrane, which will be discussed in more detail below.

For depositing oxygen doped silicon carbide films, examples of suitable precursors include cyclic siloxanes such as cyclotetrasiloxanes such as heptamethylcyclotetrasiloxane (HMCTS) and tetramethylcyclotetrasiloxane (TMCTS). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. Other examples of suitable precursors for depositing oxygen doped silicon carbide films include linear siloxanes such as, but not limited to, disiloxanes such as pentamethyldisiloxane (PMDSO), tetramethyldisiloxane (TMDSO), hexamethyl trisiloxane and heptamethyl tri siloxanes.

As described, silicon containing precursors are selected to provide highly conformal silicon carbide films. It is believed that silicon containing precursors with low adhesion coefficients can produce highly conformal films. "sticking coefficient" is used to describe the ratio of the number of adsorbed species (e.g., fragments or molecules) adsorbing/adhering to a surface to the total number of species impinging on the surface during the same period of time is a term that has been The symbol S _c is sometimes used to refer to the adhesion coefficient. The value of S _c ranges from 0 (meaning no adherent paper) to 1 (meaning all colliding papers adhere). Various factors affect the adhesion coefficient, including the type of colliding species, surface temperature, surface coverage, structural details of the surface, and kinetic energy of the colliding species. Certain species, which are inherently "sticky" than others, make them more likely to adsorb to the surface each time they collide. These more sticky species have higher adhesion coefficients (all other factors being equal) and adsorb better near the entrance of the recessed feature than the less sticky species with lower adhesion coefficients. In some cases, the adhesion coefficient of the precursors (at the relevant deposition conditions) may be about 0.05 or less, such as about 0.001 or less.

Structure and properties of the deposited film

The deposited film will include silicon, oxygen, and carbon. In some embodiments, the atomic concentration of silicon is between about 15% and 45%, the atomic concentration of oxygen is between about 10% and 40%, and the atomic concentration of carbon is between about 30% and 60%. In one example, the atomic concentration of silicon is about 30%, the atomic concentration of oxygen is about 25%, and the atomic concentration of carbon is about 45%. It will be appreciated that the relative atomic concentrations may vary with the choice of precursor. Silicon atoms will form bonds with carbon and/or oxygen atoms. In some embodiments, the deposited film includes more Si-O bonds than Si-C bonds. This can provide a relatively porous film with a lower dielectric constant. In some examples, the deposited film includes a ratio of Si-O bonds to Si-C bonds that is between about 0.5:1 and 3:1.

In some embodiments, the internal structure of the precursor remains within the deposited film. This structure may preserve all or most of the Si-C and Si-O bonds of the precursor, but via bonds and/or at positions where Si-H bonds and/or Si-Si bonds are present in the precursor molecules. or linking or crosslinking the individual precursor moieties via additional coagulation reactions on the growing surface if sufficient thermal energy is provided.

The process conditions described above can provide a very conformal film structure. Relatively weak process conditions can minimize the degree of ion bombardment at the surface of the substrate so that the deposition is not directional. Moreover, the relatively weak process conditions reduce the number of radicals with high adhesion coefficients that will tend to attach to the sidewalls of previously deposited layers or films. In certain embodiments, for an aspect ratio of about 2:1 to 10:1, the oxygen doped silicon carbide film can contain from about 25% to 100%, more typically from about 50% to 100%, even more typically from about 80% to about 80%. It can be deposited with 100% conformality. Conformality may be calculated by comparing the average thickness of the film deposited on the bottom, sidewall, or top of the feature to the average thickness of the film deposited on the bottom, sidewall, or top of the feature. For example, conformality may be calculated by dividing the average thickness of the film deposited on the sidewalls of the feature by the average thickness of the film deposited on the top of the feature and multiplying by 100 to get the percentage. For certain applications, conformality of about 85% to 95% is sufficient. In some examples of depositing silicon carbide on features having an aspect ratio of about 2:1 to about 4:1, the conformality is at least about 90%. Certain BEOLs (back end of line) fall into this category. In some examples of depositing silicon carbide on features having an aspect ratio of about 4:1 to about 6:1, the conformality is at least about 80%. Certain spacer deposition processes fall into this category. In some examples of depositing silicon carbide on features having an aspect ratio of about 7:1 to about 10:1 (even greater), the conformality is at least about 90%. Certain dynamic random access memory (DRAM) manufacturing processes fall into this category.

The process conditions can also provide a film structure with high breakdown voltage and low leakage current. By introducing a limited amount of oxygen into the SiC-like material, the leakage paths provided by Si-H bonds and/or Si-CH ₂ -Si bonds may be blocked by oxygen. This may provide improved electrical properties while maintaining a relatively low dielectric constant. In various embodiments, the film has an effective dielectric constant of about 4.5 or less, about 4.0 or less, about 3.5 or less, and in some embodiments about 3.0 or less, and still about 2.5 or less in other embodiments. The effective dielectric constant may depend on the bonding and density. In some embodiments, if applications require a relatively high dielectric constant, the oxygen doped silicon carbide film may have an effective dielectric constant greater than about 4.0 to provide a relatively dense, highly crosslinked oxygen doped silicon carbide film. can In some embodiments, the oxygen doped silicon carbide film is relatively thin and can still function as a hermetic or diffusion barrier.

In some embodiments, the deposited film may be porous. As previously discussed herein, silicon-comprising precursors may include cyclic siloxanes and caged siloxanes. These precursors and other precursors with large internal open spaces can introduce large porosity into the structure of the deposited film. The porosity of the deposited film can further lower the dielectric constant. In some embodiments, the porosity of the deposited oxygen doped silicon carbide film is between about 20% and 50%. The pore size of the porous membrane may track the size of the cyclic precursor or the caged precursor. In certain embodiments, the average pore size of the film is between about 5 Angstroms and 20 Angstroms, such as about 16 Angstroms.

The oxygen doped silicon carbide film deposited by the method of the present disclosure may have a chemical structure distinguishable from conventional SiOC films. While the oxygen-doped silicon carbide film deposited by the method of the present disclosure may be referred to as a SiOC film or SiCO film, the conventional SiOC film does not have the same chemical structure or properties as the SiOC or SiCO film deposited by the method of the present disclosure. It will be understood that no In some embodiments, the conventional SiOC film may be a carbon doped silicon oxide film distinguishable from the SiOC or SiCO films of the present disclosure. 4A shows an exemplary chemical structure of a conventional SiOC film. 4B shows an example of the chemical structure of an oxygen doped silicon carbide (SiOC or SiCO) film deposited by the method of the present disclosure.

Many conventional deposition techniques form conventional SiOC or SiOC:H with a chemical structure similar to the structure shown in FIG. 4A. For example, such SiOC or SiOC:H films are formed by doping a silicon dioxide (SiO ₂ ) film with carbon. As shown in FIG. 4A , these SiOC or SiOC:H films contain a plurality of terminal CH ₃ bonds, coordinated by oxygen and hydrogen atoms. The carbon atoms, or at least a significant fraction of the carbon atoms, are not crosslinked. In addition, the SiOC or SiOC:H films of FIG. 4A have a relatively high hydrogen content. Carbon doped silicon oxide as shown in FIG. 4A may have different properties than the oxygen doped silicon carbide structure of the present disclosure as shown in FIG. 4B .

The method of the present disclosure produces oxygen doped silicon carbide (SiOC or SiCO) films having a chemical structure similar to that shown in FIG. 4B . For example, such oxygen-doped silicon carbide films may contain one or more radical species in a substantially low energy state (eg, a ground state) that react with silicon-containing precursors, wherein one or more radical species are generated from a remote plasma source. for example, hydrogen radicals). As shown in FIG. 4B , oxygen doped silicon carbide films contain few or no terminal CH ₃ bonds to which carbon atoms are typically crosslinked or coordinated by silicon atoms. Carbon atoms, or at least a significant fraction of carbon atoms, are crosslinked and not coordinated by hydrogen or oxygen atoms. In addition, the oxygen-doped silicon carbide films of FIG. 4B have a relatively low hydrogen content.

The properties of the deposited oxygen doped silicon carbide films are comparable to those of carbon doped silicon oxide films or conventional SiOC films. Conventional SiOC or SiOC:H films having a structure similar to that shown in FIG. 4A can be easily hydrolyzed and can have a relatively low energy. For example, Si-O-CH ₃ can be readily hydrolyzed to Si-OH and HO-CH ₃ . Although the silicon atoms are coordinated by oxygen atoms in FIG. 4A , the polarity of the Si-O bonds makes the film more susceptible to fluorination and subsequent dissociation during etching processes such as HF wet etching processes. Si-O bonds of higher polarity compared to Si-C bonds increase the reactivity to acids. However, oxygen-doped silicon carbide films having a structure similar to that shown in Fig. 4B are not easily hydrolyzed, have a slow reaction, and require high energy. For example, Si-C-Si is not easily hydrolyzed. When the carbon atoms are coordinated by silicon atoms in FIG. 4b, the polarity of the Si-C bonds makes the film less susceptible to fluorination and subsequent dissociation during etching processes such as HF wet etching processes. The relative nonpolarity of Si-C bonds compared to Si-O bonds makes the oxygen-doped silicon carbide film more inert to acid. Accordingly, in some embodiments, the oxygen doped silicon carbide film may have greater wet etch resistance than carbon doped silicon oxide.

5A illustrates an FTIR plot of the chemical stability of a conventional SiOC or SiOC:H film. The FTIR plot shows a film comprising Si-CH ₃ bonds, Si-C bonds, and Si-O-Si bonds as deposited. After exposure to an etching process, such as an O ₂ /N ₂ strip process, the Si-CH ₃ bonds largely disappear. The terminal CH ₃ bonds may be easily removed so that after the O ₂ /N ₂ strip process, only Si-C bonds and Si-O-Si bonds remain largely. This shows that exemplary conventional SiOC or SiOC:H films are not chemically stable, especially when exposed to etching processes.

5B illustrates a TDS plot of the thermal stability of a conventional SiOC or SiOC:H film. The TDS plot shows the desorption of CH ₃ and H ₂ molecules from the substrate surface at higher temperatures, such as temperatures higher than 600 °C. Terminal CH ₃ bonds may be easily broken at elevated temperatures, and more hydrogen will desorb from conventional SiOC or SiOC:H films with increased hydrogen content. This shows that conventional SiOC or SiOC:H films are not thermally stable, especially when exposed to elevated temperatures.

6A illustrates an FTIR plot of the chemical stability of an oxygen doped silicon carbide (SiOC or SiCO) film deposited by the method of the present disclosure. The FTIR plot shows a film containing Si-O-Si bonds and Si-C bonds, but no Si-CH ₃ bonds. After exposure to an etching process, such as an O ₂ /N ₂ strip process, the FTIR plot remains the same. This shows that the exemplary oxygen doped silicon carbide film is chemically stable, especially when exposed to an etching process.

6B illustrates a TDS plot of the thermal stability of an oxygen doped silicon carbide film deposited by the method of the present disclosure. The TDS plot shows that at higher temperatures, such as temperatures higher than 600 °C, molecules of CH ₃ do not desorb from the substrate surface. Also, fewer H ₂ molecules are desorbed from the substrate surface in FIG. 6B compared to FIG. 5B . This shows that the oxygen doped silicon carbide film deposited by the method of the present disclosure is thermally stable.

Accordingly, the oxygen-doped silicon carbide film may have a low etch rate, may be thermally stable, and may be chemically stable. This allows the film to withstand high temperature annealing, dry/wet etching, ashing, and other manufacturing processes. Without wishing to be bound by any theory, this robustness may be due, in part, to the cross-linked Si-C bonds and the lack of CH ₃ end bonds. This kind of film can offer great performance improvements in semiconductor applications, such as low-k spacer applications.

Oxygen doped silicon carbide films may provide improved properties compared to other conventional dielectric materials, including SiOC/SiOC:H, SiO ₂ , and SiBCN. Not only can the oxygen doped silicon carbide film provide a low-k dielectric, the oxygen doped silicon carbide film can provide high breakdown voltages, high chemical stability, high thermal stability, and strong resistance to wet etching. These oxygen doped silicon carbide films are suitable for low-k spacer applications requiring integration flow involving various thermal annealing and etching steps, where the oxygen doped silicon carbide film can withstand the integration flow while maintaining low-k. It might be useful. Conventional SiOC/SiOC:H, SiO ₂ , and SiBCN films may offer low-k but may not withstand this integration flow.

Device

One aspect of the present disclosure is an apparatus configured to achieve the methods described herein. A suitable apparatus includes a system controller having hardware for accomplishing the process operations and instructions for controlling the process operations in accordance with the present disclosure. In some embodiments, an apparatus for performing the process operations described above may include a remote plasma source. The remote plasma source provides weak reaction conditions compared to the direct plasma source. An example of a suitable remote plasma device is described in US Patent Application Serial No. 14/062,648, filed Oct. 24, 2013, which is incorporated herein by reference in its entirety.

3 provides a schematic diagram of a remote plasma apparatus in accordance with certain embodiments. Device 300 includes a reaction chamber 310 having a showerhead assembly 320 . Inside the reaction chamber 310 , a substrate 330 rests on a stage or pedestal 335 . In some embodiments, the pedestal 335 may fit a heating/cooling element. A controller 340 may be coupled to components of the device 300 to control operation of the device 300 . For example, controller 340 may include instructions for controlling process conditions for operations of device 300 , such as temperature process conditions and/or pressure process conditions.

During operation, gases or gas mixtures are introduced into the reaction chamber 310 through 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 coupled to the vessel 350 , and a second gas inlet 365 can be coupled to the reaction chamber 310 and a remote plasma source 360 may be connected. In embodiments involving remote plasma configurations, delivery lines for precursors and radical species generated at the remote plasma source are separated. Accordingly, the precursors and radical species do not substantially interact before reaching the substrate 330 .

One or more radical species may be generated within the 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 within remote plasma source 360 to generate radical species. This includes, but is not limited to, capacitively coupled plasmas, inductively coupled plasmas, microwave plasmas, DC plasmas, and laser generated plasmas. An example of a capacitively coupled plasma may be an RF plasma. The high frequency plasma may be configured to operate above 13.56 MHz. An example of such a remote plasma source 360 may be GAMMA® manufactured by Novellus Systems of San Jose, California. Another example of such an RF remote plasma source 360 may be Astron® manufactured by MKS Instruments of Wilmington, Massachusetts, capable of operating at 440 kHz and in a larger apparatus for processing one or more substrates in parallel. It can be provided as a bolted-on subunit. In some embodiments, microwave plasma can be used as remote plasma source 360 , such as also Astex® manufactured by MKS Instruments. The microwave plasma may be configured to operate at a frequency of 2.45 GHz.

Precursors may be provided to a vessel 350 and supplied to the showerhead 320 via a first gas inlet 355 . The showerhead 320 dispenses the precursors into the reaction chamber 310 towards the substrate 330 . A substrate 330 may be positioned under the showerhead 320 . It will be appreciated that the showerhead 320 may have any suitable shape and may have any number and arrangement of ports for distributing gases to the substrate 330 . The precursors may be fed at a controlled flow rate to the showerhead 320 and ultimately to the substrate 330 .

One or more radical species formed within the remote plasma source 360 may be transported in a gaseous phase towards the substrate 330 . One or more radical species may flow into the reaction chamber 310 via the second gas inlet 365 . It will be appreciated that the second gas inlet 365 need not traverse the surface of the substrate 330 as illustrated in FIG. 3 . In certain 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 allows ionized species generated in the remote plasma source 360 to be substantially neutralized, while at least some radical species in substantially low energy states are adjacent to the substrate 330 . It may be configured to provide weakly reactive conditions so as to remain in the atmosphere. These low energy state radical species do not recombine to form stable compounds. The distance between the remote plasma source 360 and the reaction chamber 310 depends on the power of the plasma (e.g., determined in part by the source RF power level), and a significant fraction (e.g., if there are high concentrations of hydrogen atoms) in the reaction chamber ( 310), and the density of the gas in the plasma (which may recombine to form H ₂ ), and other factors. In some embodiments, the distance between the remote plasma source 360 and the reaction chamber 310 may be between about 10 cm and 50 cm, such as about 30 cm.

In some embodiments, a co-reactant other than a primary silicon-containing precursor or hydrogen radical may be introduced during the deposition reaction. In some implementations, when the co-reactant is at least partially converted to a plasma, the apparatus is configured to introduce the co-reactant through the second gas inlet 365 . In some implementations, 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, carbon dioxide, and the like.

The controller 340 may include instructions to control process conditions for operation of the device 300 . Controller 340 will typically include one or more memory devices and one or more processors. A processor may include a CPU or computer, analog and/or digital input/output connections, stepper motor controller boards, and the like. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on memory devices associated with controller 340 or may be provided over a network.

In certain embodiments, the controller 340 controls all or most activities of the semiconductor processing device 300 described herein. For example, the controller 340 may control all or most of the activities of the semiconductor processing device 300 associated with depositing an oxygen-doped silicon carbide film and optionally other operations of a manufacturing flow including an oxygen-doped silicon carbide film. You can also control them. The controller 340 is system control software comprising sets of instructions for controlling timing, gas composition, gas density, gas flow rates, chamber pressure, chamber temperature, RF power levels, substrate position, and/or other parameters. can also run Other computer programs, scripts, or routines stored in memory devices associated with controller 340 may be employed in some embodiments. Parameters such as RF power levels, gas flow rates to the remote plasma region, and timing of plasma ignition are adjusted and maintained by the controller 340 to provide relatively weak reactive conditions in the atmosphere adjacent the substrate 330 . can be Additionally, adjusting the substrate position may further reduce the presence of high energy radical species in the atmosphere adjacent the substrate 330 .

In a multi-station reactor, the controller 340 may include different or identical instructions for different apparatus stations, causing the apparatus stations to operate independently or synchronously.

In some embodiments, the controller 340 is configured to flow the silicon-containing precursor into the reaction chamber 310 via the first gas inlet 355 , the one or more radical species in a substantially low energy state to the remote plasma source 360 . ), and flowing one or more radical species into the reaction chamber 310 through a second gas inlet 365 to react with a silicon-comprising precursor to form an oxygen-doped silicon carbide film on the substrate 330 . It may include instructions for performing operations such as an operation.

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 the apparatus and/or a graphical software display of process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, and the like.

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

Signals for monitoring the process may be provided by analog and/or digital input connections of the system controller. Signals for controlling the process are output on analog and digital input connections.

In general, the methods described herein include a processing tool or tools, a chamber or chambers, a platform or platforms for processing, and/or specific processing components (wafer pedestal, gas flow system, etc.) for semiconductor processing. It can be performed on systems that include equipment. These systems may be incorporated into electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. In general, electronics are referred to as a controller that may control a system or various components or subparts of the systems. The controller controls delivery of processing gases, temperature settings (eg, heating and/or cooling), pressure settings, vacuum settings, power settings, depending on the processing requirements and/or type of system. , radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid transfer settings, position and motion settings, tools and other transport tools and/or It may be programmed to control any of the processes disclosed herein, including wafer transfers into and out of loadlocks coupled or interfaced with a particular system.

Generally speaking, the controller receives instructions, issues instructions, controls an operation, enables cleaning operations, enables endpoint measurements, and/or various integrated circuits, logic, memory, and/or the like. It may be defined as an electronic device with software. Integrated circuits are chips in the form of firmware that store program instructions, digital signal processors (DSP), chips defined as application specific integrated circuits (ASICs) and/or one that executes program instructions (eg, software). It may include more than one microprocessor, or microcontrollers. Program instructions may be instructions passed to a controller or system in the form of various individual settings (or program files), which define operating parameters for executing a particular process on or for a semiconductor wafer. In some embodiments, operating parameters are set by a process engineer to accomplish one or more processing steps during fabrication of one or more layers, materials (eg, silicon carbide), surfaces, circuits, and/or dies of a wafer. It may be part of a prescribed recipe.

A controller may be coupled to or part of a computer, which, in some implementations, may be integrated into, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or part of a fab host computer system that may enable remote access of wafer processing. The computer monitors the current progress of manufacturing operations, examines the history of past manufacturing operations, examines trends or performance metrics from a plurality of manufacturing operations, changes parameters of the current processing, and performs processing steps following the current processing. You can also enable remote access to the system to set up, or start a new process. In some examples, a remote computer (eg, a server) can provide process recipes to the system over a network that may include a local network or the Internet. The remote computer may include a user interface that enables input or programming of parameters and/or settings to be subsequently passed from the remote computer to the system. In some examples, the controller receives instructions in the form of data specifying parameters for each of the process steps to be performed during one or more operations. It should be understood that these parameters may be specific to the type of process to be performed and the type of tool the controller is configured to control or interface with. Accordingly, as described above, a controller may be distributed, for example, by including one or more separate controllers that are networked together and cooperate for a common purpose, such as for the processes and controls described herein. An example of a distributed controller for this purpose is one or more integrated circuits on the chamber in communication with one or more remotely located integrated circuits (eg, at the platform level or as part of a remote computer) combined to control a process on the chamber. can be circuits.

In addition to the oxygen doped silicon carbide deposition described herein, exemplary systems include a plasma etch chamber or module, deposition chamber or module, spin-rinse chamber or module, metal plating chamber or module, cleaning chamber or module, bevel edge Etch chamber or module, physical vapor deposition (PVD) chamber or module, chemical vapor deposition (CVD) chamber or module, ALD (atomic layer deposition) chamber or module, ALE (atomic layer etch) chamber or module, ion implantation chamber or module , a track chamber or module, and any other semiconductor processing systems that may be used or associated in the fabrication and/or fabrication of semiconductor wafers.

As described above, depending on the process step or steps to be performed by the tool, the controller is used in material transfer to move containers of wafers from/to tool locations and/or load ports within the semiconductor fabrication plant. may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, main computer, another controller or tools .

Applications

The present disclosure may be further understood with reference to the following applications for high quality oxygen doped silicon carbide (SiOC or SiCO) films, which applications are intended to be purely exemplary. This disclosure is not limited in scope by specific applications, which are merely examples of aspects of the disclosure.

In some embodiments, an oxygen doped silicon carbide film may be deposited over the exposed copper. In some embodiments of depositing an oxygen-doped silicon carbide film, the reaction conditions adjacent to the substrate may be free of an oxidizing agent, eg, may include O ₂ , O ₃ , and CO ₂ , radicals thereof. Thus, an oxygen-doped silicon carbide film may be deposited directly over the exposed copper without oxidizing the copper (eg, without generating cupric oxide). These films can act as etch stop layers, which can also act as copper diffusion barriers. The presence of an oxygen-doped silicon carbide film can provide a sufficiently low dielectric constant with good leakage properties to serve as a diffusion barrier. The oxygen doped silicon carbide film can be an etch stop and/or diffusion barrier by itself or as a bilayer stack (eg, a SiCO/SiNC bilayer deposited over exposed copper). In some embodiments, an oxygen-doped silicon carbide film may be disposed between adjacent metallization layers typically created by a damascene process. The oxygen-doped silicon carbide film may be resistant to etching and dense enough to minimize diffusion of copper ions into adjacent regions of the dielectric material. In some embodiments, the precursor employed for the oxygen doped silicon carbide film may not be cyclic. Non-cyclic precursors may include PMDSO or TMDSO. A precursor that is not cyclic can provide a sufficiently high density to act as a hermetic or diffusion barrier. In some embodiments, nitrogen may be incorporated into the film by employing nitrogen-comprising precursors or by plasma activating nitrogen-containing radicals such as elemental nitrogen radicals or amine radicals.

In some embodiments, the oxygen doped silicon carbide film may be deposited as vertical structures adjacent to metal or semiconductor structures. Deposition of oxygen doped silicon carbide provides excellent step coverage along sidewalls of metal or semiconductor structures to create vertical structures. In certain embodiments, vertical structures may be referred to as spacers or liners. 1B illustrates a cross-section of oxygen doped silicon carbide liners deposited on sidewalls of a gate electrode structure of a transistor. As illustrated in FIG. 1B , the transistor may be CMOS with a silicon substrate 110 having a source 112 and a drain 113 . A gate dielectric 114 may be deposited over the silicon substrate 110 , and a gate electrode may be deposited over the gate dielectric 115 to form a transistor. Oxygen doped silicon carbide spacers or liners 111 may be deposited on the sidewalls of the gate electrode 115 and the gate dielectric 114 . In another example, FIG. 1C illustrates a cross-section of oxygen doped silicon carbide deposited on sidewalls of exposed copper lines of an air gap type metallization layer. Air gaps 120 may be introduced into the integrated circuit layer between copper lines 122 , which may reduce the effective k-value of the layer. Oxygen doped silicon carbide liners 121 may be deposited on the sidewalls of the copper lines 122 , and a non-conformal dielectric layer 123 may be deposited on the air gaps 120 , the liners 121 , and It may be deposited on copper lines 122 . Examples of such air gap type metallization layers may be described in US Patent Publication No. 2004/0232552 to Fei Wang et al., which is incorporated herein by reference in its entirety for all purposes.

In some embodiments, an oxygen doped silicon carbide film may be deposited on the sidewalls of the patterned porous dielectric materials. Ultra-low-k dielectric materials can be created from porous structures. Pores in these materials can provide ingress regions of metal during deposition of subsequent layers, including deposition of diffusion barriers containing metal such as tantalum (Ta). If too much metal migrates into the dielectric material, the dielectric material may provide a short circuit between adjacent copper metallization lines. 1D illustrates a cross section of oxygen doped silicon carbide as a pore sealant for porous dielectric materials. The porous dielectric layer 132 may have a plurality of trenches or vias cut into the porous dielectric layer 132 to form pores 130 . Oxygen doped silicon carbide 131 may be deposited along the pores 130 to effectively seal the pores 130 . Sealing the pores 130 with oxygen doped silicon carbide 131 may prevent damaging the porous dielectric layer 132 that might otherwise occur by other sealing techniques using plasma. Oxygen doped silicon carbide 131 may be sufficiently dense as a pore sealant and may include non-cyclic silicon containing precursors such as PMDSO and TMDSO. In some embodiments, an etched dielectric material, such as porous dielectric layer 132 , may first be treated by a “k-repair” process, exposing porous dielectric layer 132 to UV radiation and a reducing agent. This recovery process is further described in US Patent Publication No. 2011/0111533, commonly owned by Varadarajan et al., which is incorporated herein by reference in its entirety for all purposes. In another “k-repair” process, the porous dielectric layer 132 may be exposed to UV radiation and a chemical silylating agent. This recovery process is further described in US Patent Publication No. 2011/0117678, commonly owned by Varadarajan et al., which is incorporated herein by reference in its entirety for all purposes. After exposing the pores 130 to a repair treatment that renders the surface more hydrophilic and provides a monolayer of material, the conformally deposited oxygen-doped silicon carbide 131 layer is removed from the pores of the porous dielectric layer 132 . can be deposited to effectively seal them.

In some embodiments, the oxygen doped silicon carbide film may be deposited as the ultra-low-k dielectric material itself. Ultra-low-k dielectrics have conventionally been defined as materials having a dielectric constant less than 2.5. In these configurations, the ultra-low-k dielectric material of oxygen-doped silicon carbide may be a porous dielectric layer. The pores of the dielectric layer can be introduced using cyclic or caged precursor molecules, including cyclic siloxanes and silsquioxanes. In one example, the porosity of the ultra-low-k dielectric layer of oxygen-doped silicon carbide can be between about 20% and 50%. The ultra-low-k dielectric layer may also have an average pore size of less than about 100 Angstroms, such as between about 5 Angstroms and 20 Angstroms. For example, the cyclosiloxane ring may have a radius of about 6.7 Angstroms. An increasing number and size of pores can lower the dielectric constant, while being very porous can compromise the mechanical integrity of the dielectric layer.

In some embodiments, an oxygen doped silicon carbide film 151 may be deposited in the finFET structure as a sidewall spacer. As technology nodes shrink and pitches become smaller in electronic devices, conductive features are located closer together. The separation between these conductive features becomes smaller and can lead to an increase in parasitic capacitances. Parasitic capacitances may cause delays in transmit signals, such as from transistors to interconnect lines. Instead of increasing the thickness of the dielectric material between conductive features, a material with a low dielectric constant can limit parasitic capacitances, especially when technology nodes are scaled down.

Silicon nitride (Si ₃ N ₄ ) as a sidewall spacer may offer good step coverage, thermal stability, chemical stability, chemical selectivity, and high breakdown voltages. However, the dielectric constant of silicon nitride may be unsuitably high in many electronic devices. Silicon dioxide (SiO ₂ ) films may have a lower dielectric constant sufficient for many electronic devices, but may not have sufficient wet etch resistance to withstand typical integration flow. SiO ₂ with carbon or nitrogen atoms Doping films may improve resistance to wet etch processes, but may still result in poor thermal and chemical stability. Oxygen doped silicon carbide (SiCO) films may offer sufficiently low dielectric constants with improved resistance to wet etch processes, thermal stability, chemical stability, high breakdown voltages, chemical selectivity, and good step coverage. . Such oxygen-doped silicon carbide films may maintain a low dielectric constant and may withstand an integration flow involving various thermal annealing and etching steps.

1E shows three-dimensional schematics of an exemplary integration flow for fabricating finFET structures. A finFET structure may include a plurality of gate electrodes (eg, polysilicon) parallel to each other and a plurality of “fins” of thin semiconductor material parallel to each other and extending perpendicularly from opposite sides of the gate electrodes. there is. Fins extending from one side of the gate electrode may correspond to source regions, while fins extending from an opposite side of the gate electrode may correspond to drain regions. Each of the upper ends of the gate electrodes may be covered with a gate mask. Oxygen doped silicon carbide sidewall spacers 151 may be conformally deposited on the sidewalls of the fins and gate electrodes as well as over top surfaces of the gate mask and fins. The spacer etch may remove portions of the oxygen doped silicon carbide sidewall spacer 151 from the fins and from the gate mask of the gate electrode. The NMOS epitaxial growth step may form source/drain regions on the fins. The dielectric material may fill finFET structures with an etch stop and/or a pre-metal dielectric (PMD). The gate electrodes may undergo lithographic processing steps for gate cutting and metal filling. These processing steps may involve one or more etching processes, wet cleaning processes, and photoresist stripping processes. The oxygen doped silicon carbide sidewall spacer 151 may be stable through these processing steps. The gate electrodes may further undergo contact or self-aligned contact (SAC) etch steps, which may require selectivity, plasma resistance, and wet clean resistance in the oxygen doped silicon carbide sidewall spacer 151 .

Although the foregoing has been described in some detail for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus described. Accordingly, the described embodiments are to be regarded as illustrative and non-limiting.

Claims (15)

An apparatus (300) for depositing an oxygen doped silicon carbide (SiCO) film on a substrate (330), comprising:
a reaction chamber (310) comprising a pedestal (334) for supporting a substrate (330);
a vessel (350) configured to provide a silicon-comprising precursor into the reaction chamber (310) via a first gas inlet (355), wherein the silicon-comprising precursor comprises one or both of a silicon-silicon bond and a silicon-hydrogen bond; and the vessel (350) comprising one or both of silicon-oxygen bonds and silicon-carbon bonds;
a plasma source (360) separate from the reaction chamber (310);
means for controlling the plasma source (360) to generate hydrogen radicals in the plasma source (360) from a source gas;
a second gas inlet (365) for introducing the hydrogen radicals from the plasma source (360) into the reaction chamber (310); and
To deposit a SiCO film on the substrate 330, the substrate ( 330) configured to control the plasma source 360, the flow of the silicon-comprising precursor, and the flow of the hydrogen radicals to cause at least 90% of the hydrogen radicals to ground state and react with the silicon-comprising precursor in an atmosphere adjacent to 330 a controller (340), wherein the SiCO film has an effective dielectric constant greater than 4.0, and wherein the controller (340) is configured to deposit the SiCO film at an operating temperature of 250°C to 400°C. The method of claim 1,
wherein the silicon-comprising precursor comprises cyclic siloxanes. 3. The method of claim 2,
wherein the cyclic siloxanes are selected from the group consisting of TMCTS, OMCTS, and HMCTS. 3. The method of claim 2,
wherein the cyclic siloxanes are caged siloxanes. The method of claim 1,
wherein the silicon-comprising precursor comprises alkoxy silanes. The method of claim 1,
at least some of the plurality of carbon atoms in the SiCO film are crosslinked. The method of claim 1,
and the controller (340) is configured to deposit the SiCO film without terminal Si-CH ₃ bonds. The method of claim 1,
and the controller (340) is configured to deposit the SiCO film at a ratio of silicon-oxygen bonds to silicon-carbon bonds in the SiCO film of 0.5:1 to 3:1. The method of claim 1,
wherein the substrate (330) includes a plurality of features, and the controller (340) is configured to deposit the SiCO film with conformality of at least 90% in the plurality of features. The method of claim 1,
wherein the substrate (330) comprises a transistor having a gate electrode, and the controller (340) is configured to deposit the SiCO film on one or more sidewalls of the gate electrode. An apparatus (300) for depositing an oxygen doped silicon carbide (SiCO) film on a substrate (330), comprising:
a reaction chamber (310) comprising a pedestal (334) for supporting a substrate (330);
a vessel (350) configured to provide a silicon-comprising precursor into the reaction chamber (310) via a first gas inlet (355), wherein the silicon-comprising precursor comprises one or both of a silicon-silicon bond and a silicon-hydrogen bond; and the vessel (350) comprising one or both of silicon-oxygen bonds and silicon-carbon bonds;
a plasma source (360) separate from the reaction chamber (310);
means for controlling the plasma source (360) to generate hydrogen radicals in the plasma source (360) from a source gas; and
The plasma source 360 under conditions such that at least 90% of the hydrogen radicals are in a ground state in an atmosphere adjacent to the substrate 330 and react with the silicon-comprising precursor to deposit a SiCO film on the substrate 330 . a second gas inlet (365) for introducing the hydrogen radicals into the reaction chamber (310) from reacts with the silicon-comprising precursor to destroy silicon-oxygen bonds and silicon-carbon bonds, and wherein the SiCO film has an effective dielectric constant greater than 4.0. 12. The method of claim 11,
The plasma source 360 , the flow of the silicon containing precursor, and the flow of hydrogen radicals to cause the ground state hydrogen radicals to react with the silicon containing precursor to deposit the SiCO film on the substrate 330 . and a controller (340) configured to control 13. The method of claim 12,
and the controller (340) is configured to control the temperature of the pedestal (335) such that the SiCO film is deposited at an operating temperature of 250°C to 400°C. 12. The method of claim 11,
wherein the silicon-comprising precursor comprises non-cyclic siloxanes. 12. The method of claim 11,
at least some of the plurality of carbon atoms in the SiCO film are crosslinked.

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