KR102515238B1 - Conformal deposition of silicon carbide films - Google Patents

Abstract

Methods and systems for providing silicon carbide films are disclosed. The silicon carbide layer may be provided under process conditions employing one or more silicon-containing precursors having one or more silicon-hydrogen bonds and/or silicon-silicon bonds. Silicon-containing precursors may also have one or more silicon-oxygen bonds and/or silicon-carbon bonds. One or more radical species in a substantially low energy state may react with silicon-containing precursors to form a silicon carbide film. One or more radical species may be formed in the remote plasma source.

Description

Conformal deposition of silicon carbide films {CONFORMAL DEPOSITION OF SILICON CARBIDE FILMS}

This disclosure relates generally to the formation of silicon carbide films.

BACKGROUND OF THE INVENTION Thin films of the silicon carbide (SiC) family have unique physical, chemical, and mechanical properties and are used in a variety of applications, particularly integrated circuit applications. SiC type thin films are composed of oxygen doped SiC, also known as silicon oxycarbide (SiOC), nitrogen doped SiC, also known as silicon nitriccarbide (SiNC), oxygen doped SiC, also known as silicon oxynitricarbide (SiONC), and Nitrogen-doped SiC, and undoped silicon carbide.

Methods and systems for preparing silicon carbide films are provided. A substantially conformal silicon carbide layer may be provided using a process employing silicon-containing precursors having one or more silicon-hydrogen bonds and/or silicon-silicon bonds. Silicon-containing precursors may also have one or more silicon-oxygen bonds, silicon-nitrogen bonds, and/or silicon-carbon bonds. The precursor may be formed by breaking silicon-hydrogen bond(s) while preserving one or more silicon-oxygen bonds, silicon-nitrogen bonds, and/or silicon-carbon bonds within the precursor, for example, hydrogen atoms from the precursor. or, if present in the precursor, by breaking the silicon-silicon bond(s). The resulting film may contain one or more silicon-oxygen bonds and/or silicon-carbon bonds. A precursor may also be converted to a reactive but substantially complete form by conversion to a radical species or other reactive species from which hydrogen atoms or other atoms are extracted. Hydrogen or other atoms may be extracted, for example, by exposing the precursor to radical species. In certain embodiments, one or more radical species in a substantially low energy state can react with the silicon-containing precursor(s) to form silicon carbide. One or more radical species may be formed in the remote plasma source. Silicon carbide can be used in a wide range of applications to serve as, but is not limited to, liners, spacers, etch stops, copper diffusion barriers, pore sealants, and ultra low-k dielectric layers.

Certain aspects of the present disclosure relate to a method of depositing a silicon carbide film on a substrate, the method comprising the following operations: (a) providing a substrate to a reaction chamber; (b) providing a silicon-containing precursor to the substrate, wherein the silicon-containing precursor (i) has one or more silicon-hydrogen bonds and/or silicon-silicon bonds and (ii) does not have carbon-oxygen bonds , and (iii) providing a silicon-containing precursor having no carbon-nitrogen bonds; and (c) a silicon-containing precursor to form a silicon carbide film on the substrate under conditions that destroy silicon-hydrogen bonds or silicon-silicon bonds of the silicon-containing precursor but preserve silicon-carbon bonds of the silicon-containing precursor. It may be characterized by introducing one or more radical species in a substantially lower energy state from the source gas to react with the precursor. As examples, the silicon carbide film may include oxygen doped silicon carbide, nitrogen doped silicon carbide, or undoped silicon carbide.

In some cases, the silicon-containing precursor does not have alkoxy groups (-COR) and amine groups (-C-NR ₁ R ₂ ), where R is an organic moiety, and R ₁ and R ₂ are each independently hydrogen or an organic moiety. In certain embodiments, during steps (b) and (c), no compound containing carbon-oxygen bonds or carbon-nitrogen bonds is provided to the substrate. Also, in certain implementations, the silicon carbide film is formed without performing atomic layer deposition (ALD).

In certain embodiments, the silicon-containing precursor is a cyclic siloxane such as heptamethylcyclotetrasiloxane and tetramethylcyclotetrasiloxane. In certain embodiments, the silicon-containing precursor is a linear siloxane such as disiloxane and trisiloxane. In certain embodiments, the silicon-containing precursor is an alkyl silane such as disilane or trisilane. In certain embodiments, the silicon-containing precursor is a silazane.

In certain embodiments, a radical species includes hydrogen radicals, oxygen radicals, and/or nitrogen radicals. In some implementations, introducing the one or more radical species involves exposing the source gas to a remote plasma, which may be generated from an RF power source or a microwave power source.

In certain embodiments, the ratio of silicon-oxygen bonds or silicon-nitrogen bonds to silicon-carbon bonds in the silicon carbide film is from about 3:1 to about 0.5:1. In some cases, the silicon carbide film on the substrate has a conformality of at least about 90%. In some applications, the substrate includes a transistor having a gate electrode, and the method further includes forming a silicon carbide film on one or more sidewalls of the gate electrode. In some applications, silicon carbide films include ultra-low-k dielectric thin films.

Certain aspects of the present disclosure relate to an apparatus for depositing a silicon carbide film on a substrate, the apparatus comprising the following features: a reaction chamber configured to hold a substrate during silicon carbide film deposition; a plasma chamber coupled to the reaction chamber and configured to generate a plasma outside the reaction chamber; two or more gas inlets coupled to the reaction chamber; and a controller. The controller performs the following operations: (a) flowing a silicon-containing precursor into the reaction chamber through one of the gas inlets, wherein the silicon-containing precursor has (i) one or more silicon-hydrogen bonds and/or silicon-silicon flowing a silicon-containing precursor that has bonds, (ii) does not have carbon-hydrogen bonds, and (iii) does not have carbon-nitrogen bonds; (b) providing one or more radical species in a substantially low energy state from a plasma within the plasma chamber; and (c) flowing one or more radical species into the reaction chamber through another one of the gas inlets to react with the silicon-containing precursor to form a silicon carbide film on the substrate. may be

In some designs, the device has a distance between about 1 cm and about 30 cm between the reaction chamber and the plasma chamber. In various implementations, the plasma chamber has an RF power source or a microwave power source.

In certain embodiments, the controller further includes instructions for not providing a compound containing a carbon-oxygen bond or a carbon-nitrogen bond during operations (a) through (c). In certain embodiments, the controller instructions do not include instructions for depositing a silicon carbide film using ALD.

In some embodiments, the silicon-containing precursor does not have alkoxy groups (-COR) and amine groups (-C-NR ₁ R ₂ ), where R is an organic moiety, and R ₁ and R ₂ are each independently is a hydrogen or organic moiety. In some applications, the silicon-containing precursor is a siloxane. In some embodiments, the silicon-containing precursor is an alkyl silane. In some embodiments, the silicon-containing precursor is a silazane.

In some devices, one or more radical species are produced from a gas selected from the group consisting of hydrogen, nitrogen, and ammonia. By way of example, one or more radical species are hydrogen atoms. In some applications, the ratio of silicon-oxygen bonds or silicon-nitrogen bonds to silicon-carbon bonds in the silicon carbide film is from about 3:1 to about 0.5:1. In some applications, silicon carbide films are ultra-low-k dielectric thin films.

In certain embodiments, the controller is configured to maintain the reaction chamber at a temperature between about 250 °C and about 400 °C. In certain embodiments, the controller is configured to maintain the reaction chamber at a pressure between about 0.2 Torr and about 40 Torr.

These and other embodiments are described further below with reference to the drawings.

1A illustrates a cross-section of an example of a SiC film deposited over a substrate.
1B illustrates SiC vertical structures on sidewalls of a gate electrode structure of a transistor.
1C illustrates SiC vertical structures on exposed sidewalls of copper lines in an air gap type metallization layer.
1D illustrates SiC pore sealants for porous dielectric materials.
2 illustrates examples of representative caged siloxane precursors.
3 illustrates a schematic diagram of a processing apparatus having a remote plasma source.
4 provides two micrographs comparing features with oxygen doped silicon carbide produced under similar conditions but from two different precursors, one containing alkoxy groups and the other without alkoxy groups.

The following disclosure provides various details to help explain related concepts, and may be practiced without some or all of these details. Although some concepts will be described with specific embodiments, it will be understood that these embodiments are not intended to be limiting. In some instances, well known process operations, structures, and other features have not been described in detail in order to facilitate an understanding of the described concepts.

In this specification, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of fabrication of an integrated circuit thereon. Wafers or substrates used in the semiconductor device industry typically have 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 limited thereto. A workpiece may be of various shapes, sizes and materials. In addition to semiconductor wafers, other workpieces that may take advantage of 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. do.

Introduction

Fabrication of semiconductor devices typically involves depositing one or more thin films on a substrate in an integrated circuit fabrication process. In some aspects of the fabrication process, thin films of the class SiC, SiON, SiONC, and SiCN are formed by atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or any other It is deposited using a suitable deposition method. As used herein, the term silicon carbide includes doped silicon carbides such as oxygen doped silicon carbide, nitrogen doped silicon carbide, and nitrogen and oxygen doped silicon carbide. Doped silicon carbide may have a wide range of dopant concentrations. Many doped silicon carbides have up to about 50 atomic percent of dopant atoms, which atoms are oxygen, nitrogen, or atoms of another element. The doping level provides the desired film properties. In one example, the process can make SiOC films having about 10-15 atomic percent carbon and about 40 atomic percent oxygen. In another example, the film contains about 30 to 35 atomic percent carbon and about 25 to 30 atomic percent oxygen. Of course, the electrical properties of silicon carbide films will be different. Typically, for good electrical properties, the carbon content is relatively low.

Precursor molecules for depositing SiC include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-carbon (Si-C) bonds. do. Precursor molecules for depositing SiC are silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-oxygen (Si-O) bonds, and/or silicon-carbon (Si-C) includes silicon-containing molecules having bonds. Precursor molecules for depositing SiNC may be silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-nitrogen (Si-N) bonds, and/or silicon-carbon (Si-C) includes silicon-containing molecules having bonds. Precursor molecules for depositing SiONC are silicon-hydrogen (Si-H) bonds, and/or silicon-silicon (Si-Si) bonds, and silicon-nitrogen (Si-N) bonds, silicon-oxygen (Si-Si -O) bonds, and/or silicon-containing molecules having silicon-carbon (Si-C) bonds. Current PECVD processes may use in situ plasma processing, in which plasma is provided immediately adjacent to the processed substrate.

Depositing high quality silicon carbide thin films has good step coverage, low dielectric constants, high breakdown voltages, low leakage currents, high porosity, and/or coverage over exposed metal surfaces that does not oxidize metal surfaces. It has been found that it can have specific challenges, such as providing membranes.

While this disclosure is not limited to any particular theory, it is believed that the plasma conditions of typical PECVD processes fragment the silicon-containing precursor molecules in a way that creates undesirable effects. For example, PECVD may break Si-O bonds and/or Si-C bonds in precursor molecules to produce highly reactive radicals or other fragment types with high sticking coefficients. The fragments and the resulting silicon carbide film can include “dangling” bonds of silicon, carbon, and/or oxygen atoms, wherein the “dangling” bonds do not form reactive pairs of silicon, carbon, and/or oxygen atoms. This means that atoms with no valence have electrons. Precursor molecules of high adhesion coefficients and their fragments deposit silicon carbide films with poor step coverage because reactive precursor fragments may adhere disproportionately to the upper regions of the sidewalls of recessed features and other structures. can do.

Dangling bonds can create silanol groups (Si-OH) in the deposited SiOC or SiONC film. As a result, the films may have detrimentally high dielectric constants. Film quality may also suffer because direct plasma conditions tend to extract carbon from the deposited film.

Additionally, dangling bonds can create silicon-hydrogen bonds (Si-H) within deposited silicon carbide films. Broken Si-C bonds can be replaced with Si-H under direct plasma deposition conditions. The presence of Si-H bonds in silicon carbide films can create 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 provide a leakage path for electrons.

Also, dangling bonds can cause uncontrolled chemical or morphological structures in silicon carbide films. In some cases, these structures are dense filaments with low or no porosity such that the film has an unacceptably high dielectric constant. The lack of porosity can create direct plasma conditions that break Si-C and/or Si-O bonds in the cyclic siloxanes, which would otherwise provide porosity in an ultra-low-k dielectric material.

Direct plasma conditions, which are sometimes employed in PECVD, can cause directivity in deposition because the energy to break up the precursor molecules can be low frequency which creates many ion bombardments at the surface. Directional deposition can also result in the deposition of silicon carbide films with poor step coverage. A direct plasma is a plasma (adequate concentrations of electrons and positive ions) in which the plasma resides adjacent to the substrate surface during deposition and is sometimes separated from the substrate surface only by a plasma sheath.

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

Atmosphere of the substrate surface during deposition

1A illustrates a cross-section of the resulting structure with a silicon carbide film deposited over a substrate. Film 101 can be formed under process conditions that create a relatively mild atmosphere adjacent to substrate 100 . Substrate 100 can be any wafer, semiconductor wafer, partially fabricated integrated circuit, printed circuit board, display screen, or other suitable workpiece. The process for depositing the silicon carbide film 101, depending on the type of doped structure to be created, along with other bonds such as silicon-carbon bonds, silicon-oxygen bonds, and/or silicon-nitrogen bonds, It may include one or more silicon-containing precursors having one or more Si-H bonds and/or one or more Si-Si bonds. In certain embodiments, precursors do not contain oxygen-carbon bonds or nitrogen-carbon bonds. As an example, the precursors do not contain alkoxy groups or amine groups.

Particular applications employing silicon carbide films are shown in FIGS. 1B-1D. In some embodiments, silicon-containing precursors may include silicon-oxygen-containing precursors, silicon-nitrogen-containing precursors, and/or silicon-carbon containing precursors. Silicon-oxygen containing precursors can contain one or more Si-O bonds, silicon-nitrogen containing precursors can contain one or more Si-N bonds, and silicon-carbon containing precursors can contain one or more Si-C bonds. can include In some embodiments, for example, silicon-containing precursors may include a single reactant A and Si-O and Si-C bonds, or Si-N and Si-C bonds. In some embodiments, silicon-containing precursors can include reactant B and Si-O bonds or Si-N bonds, and reactant C and Si-C bonds. It will be appreciated that any number of suitable reactants may be employed within the scope of this disclosure. The chemical structures of exemplary silicon-containing precursors are discussed in more detail below.

Silicon-containing 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 are broken and serve as reactive sites for forming bonds between silicon-containing precursors within the deposited silicon carbide film 101 . Broken bonds can also serve as sites for cross-linking during thermal processing performed during or after deposition. Bonding and cross-linking at the reactive sites can collectively form the main backbone or matrix that gives rise to the silicon carbide film (101).

In some embodiments, the process conditions may substantially preserve the Si-C and, if present, Si-O bonds and Si-N bonds in the silicon carbide film 101 layer as deposited. Accordingly, reaction conditions proximal to substrate 100 provide for breakage of Si-H bonds and/or Si-Si bonds, eg, extraction of hydrogen from broken Si-H bonds, while reaction conditions are Si-H bonds. It does not provide extraction of oxygen from O bonds, nitrogen from Si-N bonds, or carbon from Si-C bonds. In general, the reaction conditions described exist on the exposed side of the workpiece (the side on which the silicon carbide film is deposited). They may further exist at some distance above the workpiece, for example from about 0.5 μm to about 150 mm above the workpiece. In fact, activation of the precursors can occur in the gas phase at considerable distances above the workpiece. Typically, suitable reaction conditions will be uniform or substantially uniform over the entire exposed surface of the substrate, but certain applications may tolerate some variations.

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

As described elsewhere, hydrogen gas may be supplied into the remote plasma source to generate hydrogen radicals. Once created, 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 unselective decomposition of the silicon-containing precursor. For example, hydrogen radicals in an excited state can easily break Si-H bonds, Si-Si bonds, Si-N bonds, Si-O bonds, and Si-C bonds, which The composition or physical properties or electrical properties of the silicon carbide film may be altered. In some implementations, when the excited hydrogen radicals lose energy or relax, the excited hydrogen radicals may substantially become low energy state hydrogen radicals or ground state hydrogen radicals. Substantially low-energy or ground state hydrogen radicals will selectively break Si-H bonds and Si-Si bonds, while preserving largely Si-O bonds, Si-N bonds, and Si-C bonds. can In some implementations, process conditions may be provided such that the excited hydrogen radicals lose energy or relax to form substantially lower 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 energy relaxation time of the excited hydrogen radicals. The energy relaxation time for excited hydrogen radicals may be about 1x10 ^-3 seconds or less.

A state in which a significant fraction of the hydrogen atom radicals are in the ground state can be achieved by a variety of techniques. Some devices, as described below, are designed to achieve this condition. Device features and process control features can be tested and tuned to produce a mild state in which a significant fraction of the hydrogen atomic radicals are in the ground state. For example, the device may be operated and tested on charged particles downstream of the plasma source, ie in the vicinity of the substrate. The process and apparatus may be tuned until substantially no charged species are present in the vicinity of the substrate. Additionally, device features and process features may be tuned into configurations that start producing high quality silicon carbide films from standard precursors such as trimethylsilane. Relatively mild conditions supporting such film deposition are selected.

Other examples of radical species are oxygen-containing species such as elemental oxygen (atomic or biatomic) radicals, nitrogen-containing species such as nitrogen (atomic or biatomic) radicals, and ammonia radicals. N-H containing radicals, and nitrogen is selectively incorporated into the membrane. The aforementioned radical species may be generated from gases containing hydrogen, nitrogen, N-H containing species, or mixtures thereof. In some embodiments, essentially all atoms of the deposited film are provided by precursor molecules. In these cases, the low energy radicals used to drive the deposition reaction may be exclusively hydrogen or other species that do 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, radicals or even ions of higher energy states can potentially exist near the wafer plane.

In some embodiments, the process conditions are substantially sufficient to break Si-H bonds and/or Si-Si bonds, while substantially preserving Si-O bonds, Si-N bonds, and Si-C bonds. As a result, a radical species in a low energy state is employed. These process conditions may not have significant amounts of ions, electrons, or radical species in high energy states such as states above the ground state. In some embodiments, the concentration of ions in the region adjacent to the membrane is no greater than about 10 ⁷ /cm 3 . The presence of significant amounts of ions or high-energy radicals may tend to break Si-O bonds, Si-N bonds, and Si-C bonds, which have undesirable electrical properties (e.g., high dielectric constants and/or low breakdown voltages) and poor conformality. It is believed that an overly reactive atmosphere produces reactive precursor fragments with high adhesion coefficients (which tend to physically or chemically adhere to the workpiece sidewalls), resulting in poor conformability.

Silicon-containing precursors are typically delivered together with other species, particularly a carrier gas, in an atmosphere adjacent to the substrate 100 . In some implementations, silicon-containing precursors are present with radical species and other reactive species and/or other species including carrier gases. In some embodiments, silicon-containing precursors may be introduced as a mixture. Upstream from the deposition reaction surface, silicon-containing precursors may be mixed with an inert carrier gas. Examples of inert carrier gases include, but are not limited to, argon (Ar) and helium (He). Additionally, the silicon-containing precursors include some elemental or structural features (eg, ring structures, cage structures, unsaturated bonds, etc.), which are present in the silicon carbide film 101 in relatively low concentrations. It can be introduced as a mixture with a major species and a minor species, together with a minor species. The plurality of precursors may be present in equimolar or relatively similar proportions as appropriate to form the main backbone or matrix within the resulting silicon carbide film 101. In other embodiments, relative amounts of different precursors are substantially skewed from equimolarity.

In some embodiments, the one or more silicon-containing precursors are essentially deposited silicon carbide, with a small amount of hydrogen or other elements from a remote plasma providing less than about 5 atomic percent or less than about 2 atomic percent of the film mass. gives the total mass of the membrane. 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-containing precursors and a co-reactant other than the radical species. Examples of these co-reactants are 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 these contains combinations of These materials may be used as nitrating 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 portion of the carbon provided with the silicon-containing precursor. In some implementations employing a non-hydrogen co-reactant, the co-reactant is passed through the same flow path as the silicon-containing precursor, for example, a path comprising a showerhead, which would not normally be exposed directly to a plasma. is introduced into the reactor through In some embodiments, oxygen and/or carbon dioxide is introduced along with the precursor to change 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 through the same flow path as the hydrogen, such that the co-reactant is at least partially converted to radicals and/or ions. . In these implementations, both hydrogen radicals and co-reactant radicals react with the silicon-containing precursor(s) to produce a deposited silicon carbide film.

In certain embodiments in which co-reactants are used and the co-reactants are introduced into the chamber along with a species that is converted to radicals (eg, hydrogen), the co-reactant may be converted to radicals (eg, hydrogen). ) and any carrier gas(es), such as helium, are provided to the reactor in relatively small amounts compared to other gases in the reactor. For example, the co-reactant may be present in the process gases at about 0.05 mass % or less, or about 0.01 mass % or less, or about 0.001 mass % or less. For example, the reactant mixture (going into the plasma source) may be about 10 L/m He, about 200 to 500 sccm H ₂ , and about 1 to 5 sccm oxygen. When the co-reactants are introduced into the chamber with the silicon-containing precursor (eg, via a showerhead), the co-reactants will be present in higher concentrations, such as about 2% or less or about 0.1% or less. may be When the co-reactant is a relatively weak reactant (eg, a weak oxidizer such as carbon dioxide), it may be present in even higher concentrations, such as about 10% or less or about 4% or less.

The temperature of the atmosphere adjacent to the substrate 100 can be any suitable temperature that facilitates the deposition reaction, but is sometimes limited by the application of the device incorporating the silicon carbide film 101 . The temperature of the atmosphere adjacent to the substrate 100 can be controlled primarily by the temperature of the pedestal on which the substrate 100 is supported during deposition of the silicon carbide film 101 . In some embodiments, the operating temperature may be between about 50 °C and about 500 °C. For example, in many integrated circuit applications the operating temperature may be between about 200 °C and about 400 °C. In some embodiments, increasing temperature may cause increased cross-linking on the substrate surface.

The pressure of the atmosphere adjacent to the substrate 100 can be any suitable pressure to generate reactive radicals within the process chamber. In some embodiments, the pressure may be less than or equal to about 35 Torr. For example, the pressure may be between about 10 Torr and about 20 Torr, as in embodiments implementing microwave generated plasma. In other examples, the pressure may be less than about 10 Torr, or between about 0.2 Torr and about 8 Torr, as in embodiments implementing radiofrequency (RF) generated plasma.

1B-1D illustrate cross-sectional views of structures comprising silicon carbide films in various applications. 1B illustrates a silicon carbide vertical structure on the sidewalls of a gate electrode structure of a transistor. 1C illustrates a silicon carbide vertical structure on exposed sidewalls of copper lines in an air gap type metallization layer. 1D illustrates silicon carbide pore sealants for porous dielectric materials. Each of these applications is discussed in more detail below.

Chemical structure of precursors

As discussed, the precursors employed to form silicon carbide films include silicon-containing precursors having at least some of the silicon-containing precursors having at least one Si-H bond and/or at least one Si-Si bond. can do. In certain embodiments, the silicon-containing precursor has at most one hydrogen atom for 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 another atom optionally 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 two or more hydrogen atoms bonded to one or two remaining silicon atoms, and so on. Additionally, silicon-containing precursors may include at least one Si-O bond, at least one Si-N bond, and/or at least one Si-C bond. Any number of suitable precursors may be used to form the silicon carbide films, but at least some of the precursors include at least one of a Si-H bond or a Si-Si bond and optionally a Si-O bond, a Si-N bond, and/or silicon-containing precursors having at least one of a Si-C bond. In various implementations, the silicon-containing precursor(s) do not contain OC bonds or NC bonds; For example, the precursor(s) do not contain an alkoxy group (-OR) or amine groups (-NR ₁ R ₂ ), where R is an organic group such as a hydrocarbon group, and R ₁ and R ₂ are independently They are hydrogen or organic groups. It is believed that these groups may impart high sticking coefficients to the precursor or fragments in which the precursor resides. In certain embodiments, the precursor or compound delivered to the substrate during silicon carbide formation does not contain alkoxy groups or amine groups.

In certain embodiments, at least some of the carbon provided to the silicon carbide film is provided by one or more hydrocarbon moieties on the silicon-containing precursor. These moieties may be provided 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 Si-H bonds and/or Si-Si bonds that stop reactions during deposition. However, precursors are not limited to single-carbon groups, and larger numbers of carbon atoms may be used, such as 2, 3, 4, 5, or 6 carbon atoms. In certain embodiments, the hydrocarbon group is linear. In certain embodiments, the hydrocarbon group is cyclic.

In some embodiments, silicon-containing precursors belong to one of three or more chemical classes, and any precursor may exist alone as a sole precursor or in combination with other types of precursors. It will be appreciated that other chemical classifications of silicon-containing precursors may be employed and that the classification of silicon-containing precursors is not limited to the chemical classifications discussed below.

First, the silicon-containing 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) and heptamethylcyclotetrasiloxane (HMCTS). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. Embodiments using cyclic siloxanes are ring structures, which can have pores of a size corresponding to the radius of the ring, introducing porosity into the silicon carbide film. For example, a cyclotetrasiloxane ring may have a radius of about 6.7 Å.

In some embodiments, the siloxane may have a three-dimensional or caged structure. 2 illustrates examples of representative caged siloxane precursors. Cased siloxanes have silicon atoms bridged to each other via oxygen atoms to form a polyhedron or any 3-D structure. An example of a caged siloxane precursor molecule is silsesquioxane. Cased siloxane structures are described in more detail in commonly owned U.S. Pat. No. 6,576,345 to Cleemput et al., incorporated herein by reference for all purposes. Like cyclic siloxanes, caged siloxanes can introduce porosity into the 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 pentamethyldisiloxane (PMDSO) and tetramethyldisiloxane (TMDSO), and trisiloxanes such as hexamethyltrisiloxane, heptamethyltrisiloxane.

Second, the silicon-containing precursor may be an alkyl silane or other hydrocarbon-substituted silane. Alkyl silanes include a central silicon atom to which one or more hydrogen atoms are bonded as well as a central silicon atom to which one or more alkyl groups are bonded. In certain embodiments, any one of the one or more alkyl groups contains 1 to 5 carbon atoms. Hydrocarbon groups may or may not be saturated (eg, alkenes (eg, vinyl), alkynes, and aromatics). 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) do.

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

Third, the silicon-containing precursor may be a nitrogen-containing compound such as a silicon-nitrogen hydride (eg, a silazane). Generally, these compounds contain carbon and are bonded to silicon atoms as well as 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 moieties (-C-NR ₁ R ₂ ), where R ₁ and R ₂ are hydrogen atoms and hydrocarbon groups such as alkyl groups, alkene groups. , or groups that are the same as or different from the alkyne groups. Examples of suitable silicon-nitrogen precursors include cyclic silazanes and linear silazanes containing one or more hydrogen moieties bonded to one or more silicon atoms and one or more hydrogen atoms bonded to one or more silicon atoms. Includes various silazanes. Examples of silazanes include methyl-substituted disilazanes and trisilazanes such as tetramethyldisilazane and hexamethyl trisilazane.

In silicon carbide deposition, a plurality of silicon-containing precursors may be present in the process gas. For example, siloxane and alkyl silane may be used together, or siloxane and disilazane may be used together. Relative proportions of the individual precursors may be selected based on the chemical structures of the selected precursors and the application of the resulting silicon carbide film. For example, the amount of siloxane can be greater than the amount of silane in mole percent to create a porous membrane, as discussed in more detail below.

For depositing oxygen doped silicon carbide (SiOC) films, examples of suitable precursors include cyclotetrasiloxanes, such as cyclic siloxanes such as heptamethylcyclotetrasiloxane (HMCTS) and tetramethylcyclotetrasiloxane. 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, but are not limited to, disiloxanes such as pentamethyldisiloxane (PMDSO), tetramethyldisiloxane (TMDSO), hexamethyl trisiloxane, and heptamethyl trisiloxane. Includes linear siloxanes.

For undoped silicon carbide, examples of suitable precursors include, for example, monosilanes substituted with one or more alkyl, alkene, and/or alkyne groups containing 1 to 5 carbon atoms. Examples include, but are not limited to, trimethylsilane (3MS), dimethylsilane (2MS), triethylsilane (TES), and pentamethyldisilamethane.

Additionally, disilanes, trisilanes, or other higher silanes may be used in place of monosilanes. One example of such a disilane from the class of alkyl silanes is hexamethyldisilane (HMDS). Another example of a disilane from the class of alkyl silanes includes pentamethyldisilane (PMDS).

Other types of alkyl silanes may include alkylcarbosilanes, which may have a branched polymer structure having alkyl groups bonded to a silicon atom as well as carbon bonded to a silicon atom. Examples include dimethyl trimethylsilyl methane (DTMSM) and bis-dimethylsilyl ethane (BDMSE).

For depositing nitrogen-doped silicon carbide (SiNC) films, examples of suitable precursors include, for example, alkyldisilazanes and possibly an amino group (—NH ₂ ) individually bonded to one or more silicon atoms. and compounds containing alkyl groups. Alkyldisilazanes include silazanes and alkyl groups bonded to two silicon atoms. Examples include 1,1,3,3-tetramethyldisilazane (TMDSN).

As illustrated, silicon-containing precursors are selected to provide highly conformal silicon carbide films. It is believed that silicon-containing precursors with low sticking coefficients can produce highly conformal films. “Adhesion coefficient” is a term used to describe the ratio of the number of adsorbate species (e.g., fragments or molecules) that adsorb/attach to a surface to the total number of species that impinge on the surface during the same period of time. am. The symbol S _c is sometimes used to designate the sticking factor. The value of S _c ranges from 0 (meaning no adherent species) to 1 (meaning all colliding species adhere). Various factors that affect the sticking coefficient include the type of colliding species, surface temperature, surface coverage, structural details of the surface, and the kinetic energy of the colliding species. If a particular species is inherently more "sticky" than another species, it will more readily adsorb onto a surface each time it strikes it. These more adherent species have higher adhesion coefficients (all other factors being equal) and adsorb more readily near the mouth of a recessed feature compared to less adherent species having lower adhesion coefficients. In some cases, the sticking coefficient of the precursors (at 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, carbon, and in some cases oxygen, nitrogen, and/or one or more other elements. In some embodiments, the atomic concentration of silicon is between about 15% and 45% (or between about 25% and 40%), the atomic concentration of carbon is between about 10% and 50%, and the atomic concentration of oxygen is between about 0% and 40%. 45%, and the atomic concentration of nitrogen is between about 0% and 45%. In one example, the atomic concentration of silicon is about 30%, the atomic concentration of oxygen is about 25%, and the atomic concentration of carbon is about 45%. In another example, the atomic concentration of silicon is about 30%, the atomic concentration of oxygen is about 45%, and the atomic concentration of carbon is about 25%. In another example, the film contains about 10-15% carbon and about 30-40% oxygen, all on an atomic basis. In all cases, the membrane contains some hydrogen. It will be appreciated that relative atomic concentrations may vary depending on the choice of precursor. Silicon atoms will form bonds with carbon and optionally nitrogen and/or oxygen atoms. In some embodiments, the deposited film will contain 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 of between about 0.5:1 and 3:1. In some embodiments, the deposited film contains more Si-N bonds than Si-C bonds. In some examples, the deposited film includes a ratio of Si-N bonds to Si-C bonds of between about 0.5:1 and 3:1. In certain embodiments, the film density is between about 2 and 2.7 g/cm 3 .

In some embodiments, the internal structure of the precursor is maintained within the deposited film. This structure, if present in the precursor, is via bonds at locations where there are Si-H bonds and/or Si-Si bonds within the precursor molecules and/or additional condensation on the growing surface if sufficient thermal energy is provided. While linking or cross-linking individual precursor moieties through reactions, all or most of the Si-C, and Si-O and/or Si-N bonds may be preserved.

The process conditions previously described herein can provide highly conformal film structures. Relatively mild process conditions can minimize the degree of ion bombardment at the surface of the substrate so that the deposition is non-directional. Also, relatively mild process conditions can reduce the number of radicals with high adhesion coefficients that tend to adhere on the sidewalls of previously deposited layers or films. In certain embodiments, for an aspect ratio of between about 2:1 and 10:1, the silicon carbide film may have between about 25% and 100%, more typically between about 50% and 100%, even more typically between about 80% and 100%. It can also be deposited conformally. 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 sidewall of the feature by the average thickness of the film deposited on the top of the feature and multiplying by 100 to obtain a percentage. For certain applications, a conformability 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 back end of line (BEOL) processes fall within 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 within this category. In some examples of depositing silicon carbide on features having an aspect ratio of about 7:1 to about 10:1 (and even higher), 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 or nitrogen into the SiC-type material, leakage paths provided by Si-H bonds and/or Si-CH ₂ -Si bonds may be blocked by oxygen or nitrogen. The conduction mode may be different for Si-O and Si-N in low fields. This can provide improved electrical properties while maintaining a relatively low dielectric constant. In various embodiments, the film has an effective dielectric constant of about 5 or less, or about 4.0 or less, and in some cases about 3.5 or less, and in some cases about 3.0 or less, and in still other embodiments about 2.5 or less. have The effective dielectric constant may depend on bonding and density. In certain embodiments, SiOC films consist of a dielectric constant of 6 or greater, especially when the carbon content is relatively high. When leakage current is a significant factor, SiOC should be less than 5. The lower it is, the worse the hermetic and barrier and heat resistance properties will be. In some embodiments, if the applications require low hermeticity and diffusion limits, good etch resistance, thermal stability, etc., the silicon carbide film may become dense and highly cross-linked. This can be achieved, for example, by a) depositing the film at a relatively high temperature, and/or b) providing a relatively high radicals:precursor ratio. In some embodiments, the silicon carbide film may be relatively thin and still serve as an effective hermetic or diffusion barrier.

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

Device

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

3 provides a schematic diagram of a remote plasma device according to certain embodiments. Device 300 includes a reaction chamber 310 having a showerhead assembly 320 . Inside the reaction chamber 310 , a substrate 330 is placed on a stage or pedestal 335 . In some embodiments, pedestal 335 can be fitted to a heating/cooling element. A controller 340 may be coupled to components of device 300 to control operation of 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 is coupled to the reaction chamber 310, can be connected to the vessel 350, and a second gas inlet 365 is coupled to the reaction chamber 310, the remote plasma source 360. In embodiments involving remote plasma configurations, delivery lines for precursors and radical species generated within the remote plasma source are separate. Thus, the precursors and radical species do not substantially interact before reaching the substrate 330 .

One or more radical species may be generated within remote plasma source 360 and are configured to enter reaction chamber 310 via 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 a radio frequency (RF) plasma. The high frequency plasma may be configured to operate above 13.56 MHz. An example of such a remote plasma source 360 is the GAMMA® manufactured by Novellus Systems of San Jose, Calif. Another example of such an RF remote plasma source 360 is of Wilmington, Massachusetts, which can operate at 440 kHz and can be provided as a subunit mounted in a larger apparatus for processing one or more substrates simultaneously. Astron® manufactured by MKS Instruments. In some embodiments, a microwave plasma may also be used as a remote plasma source 360 such as Astex® manufactured by MKS Instruments. The microwave plasma may be configured to operate at a frequency of 2.45 GHz. The gas provided to the remote plasma source may include hydrogen, nitrogen, oxygen, and other gases, as noted elsewhere herein. In certain embodiments, hydrogen is provided to a carrier such as helium. As an example, hydrogen gas may be provided in helium at a hydrogen concentration of about 1 to 10%.

Precursors may be provided in vessel 350 and supplied to showerhead 320 via first gas inlet 355 . The showerhead 320 dispenses the precursors into the reaction chamber 310 toward the substrate 330 . Substrate 330 can be positioned below 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 . Precursors can be supplied to the showerhead 320 and ultimately to the substrate 330 at a controlled flow rate.

One or more radical species formed within the remote plasma source 360 are transported toward the substrate 330 in the gaseous phase. One or more radical species can flow into the reaction chamber 310 through the second gas inlet 365 . It will be appreciated that the second gas inlet 365 need not cross the surface of the substrate 330 as illustrated in FIG. 3 . In certain embodiments, the second gas inlet 365 can be directly above the substrate 330 or at other locations. The distance between the remote plasma source 360 and the reaction chamber 310 substantially neutralizes ionized species generated within the remote plasma source 360, but at least some radical species in substantially lower energy states proximate the substrate 330. It can be configured to provide mild reactive conditions, such as to remain in the atmosphere. These lower energy state radical species do not recombine to form stable compounds. The distance between the remote plasma source 360 and the reaction chamber 310 is determined in part by the aggressiveness of the plasma (eg, the source RF power level), the density of the gases in the plasma (eg, high concentrations of If there are hydrogen atoms, a significant fraction of the hydrogen atoms may recombine to form H ₂ before reaching the reaction chamber 310), and other factors. In some embodiments, the distance between the remote plasma source 360 and the reaction chamber 310 can be between about 1 cm and 30 cm, such as about 5 cm or about 15 cm.

In some embodiments, a co-reactant other than the main silicon-containing precursor or hydrogen radical may be introduced during the deposition reaction. In some implementations, the apparatus is configured to introduce a co-reactant through the second gas inlet 365, wherein the co-reactant is at least partially converted to a plasma. In some implementations, the apparatus is configured to introduce a co-reactant through the showerhead 320 via the first gas inlet 355 . Examples of co-reactants include oxygen, nitrogen, carbon dioxide, and the like.

Controller 340 may include instructions for controlling process conditions for operation of 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 input/output connections and/or digital input/output connections, stepper motor controller boards, and the like. Instructions to implement the appropriate control operations are executed on the processor. These instructions may be stored on memory devices associated with controller 340 or provided over a network.

In certain embodiments, the controller 340 controls all or most activities of the semiconductor processing apparatus 300 described herein. For example, controller 340 may control all or most activities of semiconductor processing device 300 associated with depositing a silicon carbide film and, optionally, other operations of a fabrication flow involving silicon carbide films. there is. Controller 340 may execute system control software that includes sets of instructions for controlling timing, gas composition, gas flow rates, chamber pressure, chamber temperature, RF power levels, substrate position, and/or other parameters. there is. Other computer programs, scripts, or routines stored on memory devices associated with controller 340 may be employed in some embodiments. Parameters such as RF power levels, gas flow rate to the remote plasma region, and plasma ignition timing can be adjusted by controller 340 to provide relatively mild reactivity conditions in the atmosphere adjacent to substrate 330. can be maintained Additionally, adjusting the substrate position may further reduce the presence of high-energy radical species in the atmosphere adjacent to the substrate 330 . In a multi-station reactor, controller 340 may include different or identical instructions for different machine stations, causing the machine stations to operate independently or in synchronization.

In some embodiments, the controller 340 controls the flow of a silicon-containing precursor into the reaction chamber 310 through the first gas inlet 355 , one or more substantially low energy states from the remote plasma source 360 . providing radical species and flowing one or more radical species into reaction chamber 310 through second gas inlet 365 to react with the silicon-containing precursor to form a silicon carbide film on substrate 330; It may also include instructions for performing operations such as.

In some embodiments, the apparatus may include a user interface associated with controller 340 . The user interface may include a display screen, graphical software displays of apparatus and/or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, and the like.

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

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

Generally, the methods described herein may be performed on semiconductor processing equipment, such as a processing tool or tools, a chamber or chambers, a platform or platforms for processing, and/or certain processing components (wafer pedestal, gas flow system, etc.) It can be performed on systems that include. These systems may be integrated with electronics to control their operation before, during and after processing of a semiconductor wafer or substrate. Electronic devices are generally referred to as controllers that may control various components or subparts of a system or 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 operation settings, tools and other transfer tools, and/or It may be programmed to control any of the processes disclosed herein, including transfers of wafers into and out of loadlocks coupled to or interfaced with a particular system.

Generally speaking, a controller has various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, and the like. It may also be defined as an electronic device. Integrated circuits are chips in the form of firmware that store program instructions, chips defined as digital signal processors (DSPs), application specific integrated circuits (ASICs) and/or one that executes program instructions (eg, software). It may include the above microprocessors or microcontrollers. Program instructions may be instructions passed to a controller or system in the form of various individual settings (or program files) that specify operating parameters for executing a specific process on or on 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 can also be part of a prescribed recipe.

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

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

As noted 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 to and from tool locations and/or load ports in a semiconductor fabrication plant. , other tool circuits or modules, other tool components, cluster tools, other tool interfaces, neighboring tools, neighboring tools, tools located throughout the plant, the main computer, another controller or tools. there is.

applications

This disclosure may be further understood by referring to the following applications for high quality silicon carbide films, the applications being intended purely as examples. This disclosure is not limited in scope by the specified applications, which are merely examples of aspects of the disclosure.

In some embodiments, a silicon carbide film may be deposited over the exposed copper. In silicon carbide film deposition, reaction conditions adjacent to the substrate may be free of oxidizing agents such as O ₂ , O ₃ , and CO ₂ including their radicals. Thus, a silicon carbide film may be deposited directly over the exposed copper without oxidizing the copper (eg, forming cupric oxide). These films can serve as etch stop layers, and can also serve as copper diffusion barriers. The presence of a silicon carbide film can provide a sufficiently low dielectric constant with good leakage properties to serve as a diffusion barrier. The silicon carbide film can be an etch stop and/or diffusion barrier, either alone or as a bilayer stack (eg, a silicon carbide/SiNC bilayer deposited over exposed copper). In some embodiments, a silicon carbide film may be placed between adjacent metallization layers, typically produced by a damascene process. The silicon carbide film can withstand etching and be sufficiently dense to minimize diffusion of copper ions into adjacent regions of the dielectric material. In some embodiments, the precursor employed for the silicon carbide film may be non-cyclic. Acyclic precursors may include PMDSO or TMDSO. Acyclic precursors can provide sufficiently high densities to serve as confining or diffusion barriers. In some embodiments, nitrogen may be incorporated into the film by employing nitrogen-containing precursors or plasma activated nitrogen-containing radicals, such as elemental nitrogen radicals or amine radicals.

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

In some embodiments, a silicon carbide film may be deposited on the sidewalls of the patterned porous dielectric materials. Ultra low-k dielectric materials can be made from porous structures. Pores in these materials can provide areas for metal ingress during deposition of subsequent layers, including deposition of diffusion barriers containing metals 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 silicon carbide as a pore sealant for porous dielectric materials. Porous dielectric layer 132 can have a plurality of trenches or vias cut into porous dielectric layer 132 to form pores 130 . Silicon carbide 131 can be deposited along the pores 130 to effectively seal the pores 130 . Sealing the pores 130 using silicon carbide 131 can prevent the porous dielectric layer 132 from being damaged, which may otherwise be caused by other sealing techniques using plasma. . Silicon carbide 131 may be sufficiently dense as a pore sealant and may include acyclic silicon-containing precursors such as PMDSO and TMDSO. In some embodiments, an etched dielectric material such as porous dielectric layer 132 may be treated by a “k-repair” process, which first exposes porous dielectric layer 132 to UV radiation and a reducing agent. This recovery process is further described in co-owned US Patent Publication No. 2011/0111533 to Varadarajan et al., incorporated herein by reference for all purposes. In another “k-repair” process, porous dielectric layer 132 can be exposed to UV radiation and a chemical silylating agent. This recovery process is further described in co-owned US Patent Publication No. 2011/0117678 to Varadarajan et al., incorporated herein by reference for all purposes. After exposing the pores 130 to a repair treatment, which renders the surface more hydrophilic and provides a monolayer of material, the conformally deposited layer of silicon carbide 131 effectively closes the pores of the porous dielectric layer 132. It can be deposited to seal.

In some embodiments, the silicon carbide film may be deposited as an 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 silicon carbide may be a porous dielectric layer. Pores in the dielectric layer can be introduced by using cyclic precursor molecules or caged precursor molecules, including cyclic siloxanes and silsesquioxanes. In one example, the porosity of the ultra low-k dielectric layer of silicon carbide can be between about 20% and 50%. Also, the ultra-low-k dielectric layer can have an average pore size of less than about 100 Å, such as between about 5 Å and 20 Å. For example, a cyclosiloxane ring may have a radius of about 6.7 Å. Increasing the number and size of pores can lower the dielectric constant, but may compromise the mechanical integrity of the dielectric layer if it is very porous.

yes

4 provides a scanning electron micrograph of two oxygen-doped silicon carbide films deposited using a precursor with an alkoxy group on the left side and a similar precursor without an alkoxy group on the right side. Other than precursor differences, the equipment and deposition conditions are the same. The feature on which films are deposited has an aspect ratio of 7:1 and a width of about 60 nm. As shown, the film produced using the alkoxy-containing precursor has a conformality of about 55% and the film produced using the alkoxy-free precursor has a conformality of about 75%.

Although the foregoing embodiments have been described in some detail for purposes of understanding and clarity, 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 described processes, systems, and apparatus. Accordingly, the present embodiments are to be regarded as illustrative and not limiting.

Claims (29)

A method of depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film comprising:
flowing a silicon-containing precursor to a substrate in a reaction chamber, the silicon-containing precursor comprising at least one of a silicon-silicon (Si-Si) bond or a silicon-hydrogen (Si-H) bond, and a silicon-carbon flowing the silicon-containing precursor comprising at least one of (Si-C) bonds, silicon-nitrogen (Si-N) bonds, or silicon-oxygen (Si-O) bonds;
generating hydrogen radicals from a source gas in a plasma source remote from the reaction chamber; and
introducing the hydrogen radicals generated from the plasma source into the reaction chamber, wherein the hydrogen radicals are directed to the silicon to deposit the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film on the substrate. reacts with a containing precursor, and wherein the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film has a conformality of at least 90% on the substrate; and a method of depositing a nitrogen doped silicon-carbon containing film. According to claim 1,
wherein the silicon-containing precursor is free of carbon-oxygen (CO) bonds and carbon-nitrogen (CN) bonds. According to claim 1,
flowing a co-reactant to the substrate in the reaction chamber, wherein the hydrogen radicals are directed to the silicon-containing precursor and the silicon-containing precursor to deposit an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film; A method of depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film that reacts with the co-reactant. According to claim 1,
The hydrogen radicals are introduced into the reaction chamber through a first gas inlet providing fluid communication between the plasma source and the reaction chamber, and the silicon-containing precursor is introduced into the reaction chamber through a second inlet downstream of the plasma source. A method of depositing an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film flowing into the reaction chamber. According to any one of claims 1 to 4,
The oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film deposits an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film having a density of 2 g/cc to 2.7 g/cc. How to. According to any one of claims 1 to 4,
wherein the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon-containing film has an effective dielectric constant of 4.0 or less. According to any one of claims 1 to 4,
The substrate has one or more recessed features, and the oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film has at least 90% of the conformality in the one or more recessed features of the substrate. A method of depositing a silicon-carbon containing film having a. According to any one of claims 1 to 4,
The oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film is deposited at a temperature of 50° C. to 500° C. and a pressure of 0.2 Torr to 8 Torr. - A method of depositing a carbon-containing film. According to any one of claims 1 to 4,
The oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film is deposited on the exposed metal surface of the substrate without oxidizing the exposed metal surface. A method for depositing a silicon-carbon containing film. A method of depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film comprising:
flowing a silicon-containing precursor to a substrate in a reaction chamber, the silicon-containing precursor comprising at least one of a silicon-silicon (Si-Si) bond or a silicon-hydrogen (Si-H) bond, and a silicon-carbon (Si-C) bond, silicon-nitrogen (Si-N) bond, or silicon-oxygen (Si-O) bond, wherein the silicon-containing precursor comprises carbon-oxygen (CO) bonds and carbon flowing the silicon-containing precursor, wherein the substrate is free of nitrogen (CN) bonds and the substrate includes one or more recessed features;
generating radicals from a source gas in a plasma source remote from the reaction chamber; and
introducing the radicals generated from the plasma source into the reaction chamber, wherein the radicals are directed to the silicon-containing film to deposit the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film on the substrate. reactive with a precursor, and wherein the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film has at least 90% conformality in the one or more recessed features; A method of depositing an oxygen and nitrogen doped silicon-carbon containing film. According to claim 10,
wherein the silicon-containing precursor is deposited under conditions that are free or substantially free of ions and high energy radicals in an atmosphere adjacent to the substrate. According to claim 10,
wherein the radicals are generated from a source gas of hydrogen gas to generate hydrogen radicals. According to claim 10,
wherein the oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film comprises a silicon oxycarbide (SiCO) film, a silicon nitric carbide (SiNC) film, or a silicon oxynitricarbide (SiONC) film. , nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing films. According to any one of claims 10 to 13,
wherein the radicals are generated from a capacitively coupled plasma of the plasma source. According to any one of claims 10 to 13,
The radicals are introduced into the reaction chamber through a first gas inlet providing fluid communication between the plasma source and the reaction chamber, and the silicon-containing precursor is introduced into the reaction chamber through a second inlet downstream of the plasma source. A method of depositing an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film flowing into a reaction chamber. A method of depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film comprising:
flowing a silicon-containing precursor to a substrate in a reaction chamber, the silicon-containing precursor comprising at least one of a silicon-silicon (Si-Si) bond or a silicon-hydrogen (Si-H) bond, and a silicon-carbon (Si-C) bond, silicon-nitrogen (Si-N) bond, or silicon-oxygen (Si-O) bond, wherein the silicon-containing precursor comprises carbon-oxygen (CO) bonds and carbon - flowing the silicon-containing precursor, which is free of nitrogen (CN) bonds;
generating radicals from a source gas in a plasma source remote from the reaction chamber; and
introducing the radicals generated from the plasma source into the reaction chamber, wherein the radicals are directed to the silicon-containing film to deposit the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film on the substrate. Reacted with a precursor, the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film has at least 90% conformal on the substrate, and the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film The silicon-carbon containing film is deposited under conditions that promote etch resistance, thermal stability, and density of the oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film. A method of depositing a doped silicon-carbon containing film. 17. The method of claim 16,
The oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film deposits an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film having a density of 2 g/cc to 2.7 g/cc. How to. 17. The method of claim 16,
wherein the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon-containing film has an effective dielectric constant of 4.0 or less. 17. The method of claim 16,
wherein the conditions include reaction conditions that are free or substantially free of ions and high energy state radicals in an atmosphere adjacent to the substrate. 17. The method of claim 16,
wherein the conditions include a temperature of 50° C. to 500° C. and a pressure of 0.2 Torr to 8 Torr. According to any one of claims 16 to 20,
oxygen doping, wherein the source gas includes hydrogen gas, the radicals generated from the plasma source include hydrogen radicals, and the conditions include hydrogen radicals in a substantially low energy state in an atmosphere adjacent to the substrate; A method of depositing a silicon-carbon containing film doped with nitrogen or doped with oxygen and nitrogen. According to any one of claims 16 to 20,
flowing a co-reactant into the substrate within the reaction chamber, wherein the radicals are directed to the silicon-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film to deposit on the substrate. oxygen doping, which reacts with the containing precursor and the co-reactant, wherein the composition of the oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film is based at least in part on the chemistry of the co-reactant; A method of depositing a silicon-carbon containing film doped with nitrogen or doped with oxygen and nitrogen. 23. The method of claim 22,
wherein the co-reactant comprises carbon dioxide, carbon monoxide, water, methanol, oxygen, ozone, or combinations thereof. 23. The method of claim 22,
wherein the co-reactant flows along a flow path of the source gas from the plasma source to the reaction chamber. According to any one of claims 16 to 20,
The radicals are introduced into the reaction chamber through a first gas inlet providing fluid communication between the plasma source and the reaction chamber, and the silicon-containing precursor is introduced into the reaction chamber through a second inlet downstream of the plasma source. A method of depositing an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film flowing into a chamber. An apparatus for depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film comprising:
means for supporting a substrate within the reaction chamber;
means for generating a capacitively coupled plasma remote from the reaction chamber, the capacitively coupled plasma comprising hydrogen radicals;
A means for delivering a silicon-containing precursor into the reaction chamber, wherein the silicon-containing precursor comprises at least one of a silicon-silicon (Si-Si) bond or a silicon-hydrogen (Si-H) bond, and includes at least one of a carbon (Si-C) bond, a silicon-nitrogen (Si-N) bond, or a silicon-oxygen (Si-O) bond, wherein the silicon-containing precursor comprises carbon-oxygen (CO) bonds and means for delivering the silicon-containing precursor free of carbon-nitrogen (CN) bonds; and
Delivering the hydrogen radicals into the reaction chamber under conditions that cause the hydrogen radicals to react with the silicon-containing precursor to deposit the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film on the substrate. wherein the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film has a conformality of at least 90% on the substrate, and the means for delivering the silicon-containing precursor transfers the hydrogen radicals. An apparatus for depositing an oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film located downstream of the means. 27. The method of claim 26,
wherein the conditions include reaction conditions that are free or substantially free of ions and high energy state radicals in an atmosphere adjacent to the substrate. 27. The method of claim 26,
The substrate includes one or more recessed features, and the oxygen-doped, nitrogen-doped, or oxygen and nitrogen-doped silicon-carbon containing film exhibits at least 90% of the conformality in the one or more recessed features. An apparatus for depositing a silicon-carbon containing film having oxygen doped, nitrogen doped, or oxygen and nitrogen doped. 27. The method of claim 26,
The oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film deposits an oxygen doped, nitrogen doped, or oxygen and nitrogen doped silicon-carbon containing film having a density of 2 g/cc to 2.7 g/cc. device to do it.

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