FORMING INTERMETAL NITRIDE PHASE IN METAL NITRIDE LAYER

Abstract

Examples are disclosed that relate to forming, in a cobalt nitride layer, an intermetal nitride phase that inhibits cobalt mobility in the cobalt nitride layer. One example provides a method for processing a substrate. The method comprises introducing a gas-phase metal-containing precursor into a processing chamber to expose a cobalt nitride layer on a substrate in the processing chamber to the gas-phase metal-containing precursor, thereby forming an intermetal nitride phase in at least a surface region of the cobalt nitride layer. The method further comprises depositing the dielectric etch stop layer onto the cobalt nitride layer.

Description

BACKGROUND

Integrated circuits comprise circuit elements connected by metal lines that extend through dielectric materials. Some integrated circuits utilize metal lines formed from copper that is capped with a cobalt nitride layer. The cobalt nitride layer helps inhibit outward diffusion of copper.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

Examples are disclosed that relate to forming, in a metal nitride layer, an intermetal nitride phase that inhibits metal mobility in the metal nitride layer. One example provides a method for processing a substrate. The method comprises introducing a gas-phase metal-containing precursor into a processing chamber to expose a metal nitride layer on the substrate to the gas-phase metal-containing precursor, thereby forming an intermetal nitride phase in at least a surface region of the metal nitride layer. The method further comprises depositing a dielectric etch stop layer onto the metal nitride layer.

In some such examples, the metal nitride layer comprises a cobalt nitride layer.

In some such examples, exposing the cobalt nitride layer to the gas-phase metal-containing precursor comprises exposing the cobalt nitride layer to an organoaluminum precursor.

In some such examples, exposing the cobalt nitride layer to the organoaluminum precursor additionally or alternatively comprises exposing the cobalt nitride layer to one or more of trimethylaluminum, triethylaluminum, or triisobutylaluminum.

In some such examples, the gas-phase metal-containing precursor additionally or alternatively comprises an organometallic chemical comprising aluminum, beryllium, magnesium, titanium, or tungsten.

In some such examples, the method additionally or alternatively comprises performing a pretreatment to remove at least some oxide from the cobalt nitride layer before introducing the gas-phase metal-containing precursor into the processing chamber.

In some such examples, the dielectric etch stop layer additionally or alternatively comprises silicon carbon nitride.

In some such examples, exposing the cobalt nitride layer to the gas-phase metal-containing precursor additionally or alternatively comprises exposing the cobalt nitride layer to the gas-phase metal-containing precursor for a duration of 1 to 60 seconds.

In some such examples, the method additionally or alternatively comprises annealing the substrate.

Another example provides a method for processing a substrate. The method comprises exposing a cobalt nitride layer on the substrate to aluminum, thereby forming a cobalt-aluminum nitride phase in at least a surface region of the cobalt nitride layer. The method further comprises depositing a dielectric etch stop layer onto the cobalt-aluminum nitride phase of the cobalt nitride layer.

In some such examples, the method further comprises performing a pretreatment to remove at least some cobalt oxide from the cobalt nitride layer before exposing the cobalt nitride layer to aluminum.

In some such examples, exposing the cobalt nitride layer to the aluminum additionally or alternatively comprises exposing the cobalt nitride layer to an organoaluminum precursor comprising one or more of trimethylaluminum, triethylaluminum, or triisobutylaluminum.

In some such examples, exposing the cobalt nitride layer to the organoaluminum precursor additionally or alternatively comprises exposing the cobalt nitride layer to the organoaluminum precursor for a duration in a range of 1 to 60 seconds.

In some such examples, exposing the cobalt nitride layer to the aluminum additionally or alternatively comprises exposing the cobalt nitride layer to an aluminum halide.

In some such examples, depositing the dielectric etch stop layer additionally or alternatively comprises depositing a low-dielectric constant (low-k) dielectric etch stop layer.

In some such examples, depositing the low-k dielectric etch stop layer additionally or alternatively comprises depositing silicon carbon nitride.

In some such examples, the method additionally or alternatively further comprises annealing the substrate.

Another example provides a substrate structure comprising a metal line comprising a conductor. The substrate structure further comprises a dielectric etch stop layer. The substrate structure further comprises a cobalt nitride layer disposed between the metal line and the dielectric etch stop layer, at least a portion of the cobalt nitride layer adjacent to an interface with the dielectric etch stop layer comprising an intermetal nitride phase.

In some such examples, the intermetal nitride phase comprises cobalt-aluminum nitride.

In some such examples, the dielectric etch stop layer additionally or alternatively comprises silicon carbon nitride.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B schematically illustrate the formation of voids in a cobalt nitride layer during an annealing process.

FIGS. 2A-2D schematically show structures formed in a process for forming an intermetal nitride phase in a cobalt nitride layer, followed by a deposition of an etch stop layer and an anneal step.

FIG. 3 shows a flow diagram depicting an example method for forming an intermetal nitride phase in a cobalt nitride layer.

FIG. 4 schematically shows an example processing tool for exposing a substrate to a metal-containing precursor to form an intermetal nitride phase in a cobalt nitride layer.

FIG. 5 shows a block diagram of an example computing system.

DETAILED DESCRIPTION

The term “aluminum-containing precursor” generally represents a chemical that can form a cobalt-aluminum nitride phase in a cobalt nitride layer when the cobalt nitride layer is exposed to the aluminum-containing precursor in a processing chamber. Example aluminum-containing precursors can include organoaluminum precursors and aluminum halides.

The term “aluminum halide” generally represents a chemical comprising aluminum bonded to halogen atoms. Examples include aluminum trichloride (AlCl₃), aluminum tribromide (AlBr₃), and aluminum triiodide (AlI₃).

The term “anneal” and variants thereof generally represent a process in which a substrate is heated for a duration, for example, to alleviate internal stresses and/or reduce defect concentrations.

The term “atomic layer deposition” (ALD) generally represents a process in which a film is formed on a substrate in one or more individual layers by sequentially adsorbing a precursor conformally to the substrate and reacting the adsorbed precursor to form a film layer. Examples of ALD processes comprise plasma-enhanced ALD (PEALD) and thermal ALD (TALD). PEALD and TALD respectively utilize a plasma and heat to facilitate a chemical conversion of a precursor adsorbed to a substrate to a film on the substrate.

The term “chemical vapor deposition” (CVD) generally represents a process in which a solid phase film is formed or modified on a substrate by directing a flow of one or more precursor gases over the substrate surface under conditions configured to cause the film formation or conversion. Plasma enhanced chemical vapor deposition (PECVD) utilizes a plasma to facilitate the film formation or conversion.

The term “cap” generally represents a layer of material at least partially surrounding a metal line. A cap can be used to help prevent diffusion of the metal into surrounding substrate regions. For example, a cobalt nitride layer can be used as a cap on a copper metal line. In further examples, a cap may comprise another material, such as tantalum, tantalum nitride, tungsten, copper, ruthenium, or molybdenum.

The term “dielectric etch stop layer” generally represents an electrically insulating material on a substrate having a lower etch rate compared to another material on the substrate in an etching process.

The term “evaporation” generally represents a process for depositing a film on a substrate by evaporating a source material in a reduced pressure environment and condensing the evaporated source material on the substrate.

The term “low-k dielectric etch stop layer” generally represents a dielectric etch stop layer with a dielectric constant (k) that is equal or lower than k for silicon oxide. A low-k dielectric etch stop layer can have a k of ≤3.9. Example low-k dielectric materials include silicon carbon nitride (SiC_(1-x)N_(1.333x), 0<x<1, hereinafter referred to as SiCN), fluorine-doped silicon oxides, silicon oxycarbide, boron nitride, and boron carbon nitride.

The term “flow control hardware” generally represents components that fluidly connect one or more chemical sources with a processing chamber. Flow control hardware can comprise one or more mass flow controllers and/or valves, for example.

The term “intermetal nitride phase” generally represents a mixture of two or more different metals and one or more non-metals including nitrogen in a solid phase.

The term “metal-containing precursor” generally represents a molecule comprising a metal atom that can be incorporated into a cobalt nitride layer to form an intermetal nitride phase. Example metal-containing precursors can include organometallic chemicals and metal halides. The term “metal atom” generally represents neutral and ionic metal atoms.

The term “metal halide” generally represents a chemical comprising a metal atom bonded to halogen atoms. Example metal halides include aluminum halides.

The term “metal line” generally represents an electrically conductive connector between circuit components in an integrated circuit. Example metal lines include interconnects in an integrated circuit.

The term “organoaluminum precursor” generally represents a molecule comprising a carbon-aluminum bond. An organoaluminum precursor has a general structure R₃—Al, wherein at least one ligand R comprises a substituted or unsubstituted aliphatic group or substituted or unsubstituted aryl group. In some organoaluminum precursors, one or two ligands R can independently comprise a hydride or a halide. Example organoaluminum precursors include trialkylaluminum compounds, such as trimethylaluminum, triethylaluminum, and triisobutylaluminum. Other example organoaluminum precursors include dimethylaluminum chloride, diethylaluminum chloride, and diisobutylaluminum hydride. Some gas phase trialkylaluminum compounds can comprise dimers. For example, diethylaluminum can dimerize to Al₂(C₂H₅)₄(μ-C₂H₅)₂.

The term “organometallic chemical” generally represents a molecule comprising a carbon-metal bond, where the metal can form an intermetal nitride phase with cobalt nitride. Examples of organometallic chemicals include organometallic chemicals having a general structure MR_n, 2≤n≤6, wherein each R ligand can independently comprise a substituted or unsubstituted aryl or aliphatic group. In some organometallic chemicals, one or more R ligands independently can comprise a hydride or a halide. M represents any suitable metal for forming an intermetal nitride phase with cobalt in a semiconductor substrate. Example metals M can include aluminum (Al), beryllium (Be), magnesium (Mg), titanium (Ti), and tungsten (W). Example organometallic chemicals can include, in addition to the organoaluminum precursors listed above, diethylberyllium (Be(C₂H₅)₂), dimethyl magnesium ((CH₃)₂Mg), diethylmagnesium ((C₂H₅)₂Mg), tetrabenzyl titanium ((C₆H₅)₄Ti), titanium tetrachloride (TiCl₄), titanium isopropoxide (Ti(OCH(CH₃)₂)₄), tungsten hexafluoride (WF₆), tungsten hexachloride (WC₁₆), hexamethyl tungsten (W(CH₃)₆), bis(tert-butylimino) bis(dimethylamino) tungsten (C₁₂H₃₀N₄W), and tungsten hexacarbonyl (W(CO)₆).

The term “plasma” generally represents a gas comprising cations and free electrons.

The term “pretreatment” generally represents a process to remove oxide from a cobalt nitride surface.

The term “processing chamber” generally represents an enclosure in which chemical and/or physical processes are performed on substrates. The pressure, temperature and atmospheric composition within a processing chamber can be controllable to perform the chemical and/or physical processes.

The term “processing tool” generally represents a machine including a processing chamber and other hardware configured to enable substrate processing to be carried out in the processing chamber.

The term “sputtering” generally represents a process for forming a thin film by bombarding a target material with ions formed in a plasma. Ions impacting the target cause some target material to be ejected from the target. The target material ejected from the target condenses on a substrate to form a film.

The term “substrate” generally represents any object on which a film can be deposited.

The term “substrate support” generally represents any structure for supporting a substrate in a processing chamber. Examples comprise pedestals, electrostatic chuck pedestals, and showerhead pedestals used for backside deposition processes.

The term “surface region” generally represents a volume of a material layer extending from a surface of the material layer partially into a bulk portion of the material layer.

The term “void” generally represents a volume of space within a film on a substrate that is lacking a solid material.

As mentioned above, integrated circuits comprise metal lines connecting circuit elements. Copper is often used as a conductor in integrated circuits. However, copper atoms can be relatively mobile in materials used to form integrated circuits. To protect an integrated circuit from copper diffusion, copper lines can be capped with a cobalt nitride layer.

Some integrated circuit fabrication processes involve depositing a dielectric layer over a metal line. The dielectric layer can act as an etch stop layer in later processes. The dielectric constant of the etch stop layer can affect capacitance between adjacent metal lines. Thus, a low-k (low dielectric constant) dielectric material can be used to form the etch stop layer. The use of a low-k dielectric material as an etch stop layer can provide for less capacitance between adjacent metal lines than a relatively higher k dielectric material. This can provide a relatively lower a resistive-capacitive (RC) time constant for a metal line compared to the RC time constant for the metal line bordered by a higher-k dielectric material.

However, in some integrated circuit manufacturing processes, an annealing process can be performed after depositing a low-k etch stop layer on a metal line capped with cobalt nitride. Such annealing can cause voids to form in a cobalt nitride layer. For example, voids can be formed during annealing when using silicon carbon nitride (SiCN) or silicon carbon oxide (SiOC) as an etch stop layer on a cobalt nitride layer. In other examples, a metal line can be capped with a different metal nitride, such as tantalum nitride.

FIGS. 1A-1B schematically show an example of void formation in a cobalt nitride layer. Dimensions of the structures illustrated in FIGS. 1A-1B and elsewhere herein are exaggerated for illustration and are not accurate to scale. First referring to FIG. 1A, a substrate 100 comprises a copper metal line 102 disposed in a dielectric layer 104. Copper metal line 102 is capped with a cobalt nitride layer 106. Substrate 100 further comprises an etch stop layer 108 disposed on cobalt nitride layer 106. A portion of cobalt nitride layer 106 is disposed between copper metal line 102 and etch stop layer 108.

FIG. 1B shows substrate 100 after performing an annealing process. Annealing can be performed, for example, to reduce stress and/or reduce a concentration of defects in various material layers. However, annealing can form voids 110 form in cobalt nitride layer 106 near the interface with etch stop layer 108. The voids can arise from cobalt mobility when the substrate is heated for annealing. Voids can cause various issues. For example, voids can lead to reduced adhesion between cobalt nitride layer 106 and etch stop layer 108. This can potentially result in a degree of delamination of the etch stop layer. Further, voids 110 can reduce the effectivity of the cobalt nitride layer in preventing diffusion of copper.

Accordingly, examples are disclosed that relate to forming, in a cobalt nitride layer, an intermetal nitride phase that inhibits cobalt mobility in the cobalt nitride layer. This can help to avoid void formation when annealing a substrate comprising a cobalt nitride layer disposed on a metal line. In some examples, the cobalt nitride layer is exposed to an aluminum-containing precursor to form an intermetal nitride phase comprising cobalt and aluminum. The intermetal nitride phase can suppress cobalt mobility and inhibit void formation during subsequent annealing. Further, in such an example, some aluminum can remain on a surface of the cobalt nitride layer. The surface metal atoms can help to strengthen an adhesion between the cobalt-aluminum nitride layer and the etch stop layer. The surface metal atoms can also help protect the cobalt nitride layer from processing gases used in a later etch stop layer deposition step. In other examples, metals other than aluminum can be used. Examples of other metals for forming an intermetal nitride phase with cobalt nitride include beryllium, magnesium, titanium, and tungsten.

In some examples, an intermetal nitride phase in a cobalt nitride layer is performed by exposing a cobalt nitride layer to a gas-phase metal-containing precursor in a chemical vapor deposition (CVD) process without the use of a plasma. Such an exposure can be referred to as a soak. In the example of aluminum, a cobalt nitride layer can be exposed to an organoaluminum precursor, such as trimethylaluminum, in a soak. Exposure times of seconds can be sufficient to form the intermetal nitride phase in a surface region of the cobalt nitride layer. Example soak times can include times within a range of 1 to 60 seconds in some examples. In other examples, soak times outside of this range can be used. Other example processing parameters to use for a soak are described below.

Other processes than a soak also can be used to expose a cobalt nitride layer to another metal to form an intermetal nitride phase. For example, a material comprising the metal to be introduced into the cobalt nitride layer can be deposited by plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), and/or physical vapor deposition methods such as sputtering or evaporation of the metal. The metal can then migrate from the deposited material into the cobalt nitride layer to form the intermetal nitride phase.

FIGS. 2A-2D schematically shows structures formed in an example process for forming an intermetal nitride phase on the surface of a cobalt nitride layer, followed by deposition of an etch stop layer. FIGS. 2A-2D are described with regard to the formation of a cobalt-aluminum nitride phase, but in other examples other intermetal nitride phases can be formed. Examples include cobalt-beryllium nitride, cobalt-magnesium nitride, cobalt-titanium nitride, and cobalt-tungsten nitride. In some examples, an intermetal nitride phase can be formed on the surface of a tantalum layer, tantalum nitride layer, a tungsten layer, a copper layer, a ruthenium layer, or a molybdenum layer. As such, in some examples, the intermetal nitride phase can comprise tantalum, tungsten, copper, ruthenium, or molybdenum. In other examples, an intermetal nitride phase can be formed on any other suitable metal.

FIG. 2A schematically shows a sectional view of a portion of a substrate 200 comprising a copper metal line 202. Copper metal line 202 is capped with a cobalt nitride layer 204. Other structures, such as a low-k dielectric layer bordering copper metal line 202 and cobalt nitride layer 204, are omitted in the views of FIGS. 2A-2D. Next, FIG. 2B shows substrate 200 following exposure of cobalt nitride layer 204 to aluminum. In some examples, the exposure of cobalt nitride layer 204 to aluminum can be performed using a soak method as described above. In a soak process, substrate 200 can be placed in a deposition chamber. Then, a gas-phase aluminum-containing precursor can be introduced into the deposition chamber. The gas-phase aluminum-containing precursor can contact cobalt nitride layer 204 and react with the cobalt nitride layer to form a cobalt-aluminum nitride phase 206. Cobalt-aluminum nitride phase 206 is indicated by a gradient in the shade of cobalt nitride layer 204. This gradient can represent a concentration gradient of aluminum in the cobalt nitride layer 204. For example, a region of the cobalt nitride layer 204 at a surface 208 of cobalt nitride layer 204 can have a higher concentration of aluminum than a region of cobalt nitride layer 204 farther from the surface 208. A concentration of aluminum also can remain on surface 208 of the cobalt-aluminum nitride phase 206. In other examples, cobalt nitride layer 204 can be exposed to aluminum using a physical vapor deposition method, such as evaporation or sputtering of aluminum metal. In further examples, cobalt nitride layer 204 can be exposed to aluminum by depositing a thin film of a suitable aluminum-containing material onto cobalt nitride layer 204 using PECVD, ALD, or other thin film deposition technique.

The cobalt nitride layer 204 can be exposed to any suitable aluminum-containing precursor in a soak process. In some examples, the aluminum-containing precursor comprises an organoaluminum precursor or an aluminum halide. Example organoaluminum precursors include trimethylaluminum, triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, and diisobutylaluminum hydride. Example aluminum halides include aluminum chloride (AlCl₃), aluminum bromide (AlBr₃), and aluminum iodide (AlI₃). In some examples, use of an aluminum halide can create an acidic environment in a processing chamber. In such examples, the acidic environment can be at least partially neutralized by introducing an oxidant or other suitable chemical to remove halogen species.

Referring next to FIG. 2C, after forming the cobalt-aluminum nitride phase 206, a dielectric etch stop layer 210 is deposited onto the cobalt-aluminum nitride phase 206. In some examples, aluminum at the surface of the cobalt-aluminum nitride phase 206 forms an interface film 222. In other examples, such as where dielectric etch stop layer 210 comprises silicon carbon nitride (SiCN) formed using nitridating gases (e.g., ammonia), interface film 222 can comprise an aluminum-nitride-type film which can shield the cobalt nitride layer from process gases.

FIG. 2D shows substrate 200 at a later process step, after an annealing step has been performed. Various process steps can be performed between the deposition of dielectric etch stop layer 210 and annealing. Unlike the structure shown in FIG. 1B, no voids have formed in the cobalt nitride layer 204, including the cobalt-aluminum nitride phase 206. The cobalt-aluminum nitride phase 206, including aluminum atoms on the surface of the cobalt-aluminum nitride phase 206, helps inhibit void formation in cobalt nitride layer 204. This can provide for suitably strong adhesion between an etch stop layer and cobalt nitride layer comprising the intermetal nitride phase. This can also help avoid disrupting the copper migration-inhibiting effect of the cobalt nitride.

FIG. 3 shows a flow diagram for an example method 300 for exposing a metal nitride layer to a metal to form an intermetal nitride phase on the metal nitride layer. Examples of metal nitride layers include cobalt nitride and tantalum nitride. In examples that include cobalt nitride, a layer of cobalt oxide can be present on a surface of the cobalt nitride layer. As such, method 300 can optionally comprises performing a pretreatment at step 302 to remove at least some cobalt oxide from the cobalt nitride layer. As one example, ammonia can be used to reduce cobalt oxide at the surface and remove at least some oxide. In some such examples, the pretreatment can comprise exposing the cobalt nitride layer to a direct plasma comprising nitrogen/ammonia. Ammonia and/or nitrogen radicals in the plasma can reduce the cobalt nitride surface and help to remove oxide. In other examples, a similar treatment can be performed using a remote plasma.

Method 300 further comprises, at step 304, exposing a metal nitride layer on the substrate to a metal to form an intermetal nitride phase in at least a surface region of the metal nitride layer. In some examples, the metal nitride layer comprises cobalt nitride and method 300 comprises exposing the cobalt nitride layer to the metal at 305. The cobalt nitride layer can be exposed to the metal in various manners. For example, as indicated at 306, in some examples the cobalt nitride layer can be exposed to a gas-phase metal-containing precursor. The exposure can take the form of a soak in which the cobalt nitride layer is exposed to the gas-phase metal-containing precursor for a period of time under conditions configured to cause reaction of the metal-containing precursor with the silicon nitride layer to form the intermetal nitride phase. The exposure also can take the form of a PECVD process, an ALD process, physical vapor deposition process, or other deposition process.

The metal-containing precursor can comprise any suitable metal element. In some examples, as indicated at 307, the metal-containing precursor can comprise one of aluminum, beryllium, magnesium, titanium, or tungsten. Such metal-containing precursors respectively may be used to form intermetal nitride phases of cobalt-aluminum nitride, cobalt-beryllium nitride, cobalt-magnesium nitride, cobalt-titanium nitride, or cobalt-tungsten nitride. As more specific examples, method 300 can comprise exposing the cobalt nitride layer to an organoaluminum precursor, as indicated at 308. Example organoaluminum precursors include alkylaluminum compounds. In some such examples, method 300 can comprise exposing the cobalt nitride layer to one or more of trimethylaluminum, triethylaluminum, or triisobutylaluminum, as indicated at 310. Other example organoaluminum precursors include dimethylaluminum chloride, diethylaluminum chloride, and diisobutylaluminum hydride. In other examples, an aluminum halide can be used. Example aluminum halides can include aluminum chloride (AlCl₃), aluminum fluoride (AlF₃), aluminum bromide (AlBr₃), and aluminum iodide (AlI₃).

Further examples of metal-containing precursors can include diethylberyllium (Be(C₂H₅)₂), dimethyl magnesium ((CH₃)₂Mg), diethyl magnesium ((C₂H₅)₂Mg), tetrabenzyl titanium ((C₆H₅)₄Ti), titanium tetrachloride (TiCl₄), titanium isopropoxide (Ti(OCH(CH₃)₂)₄), tungsten hexafluoride (WF₆), tungsten hexachloride (WCl₆), hexamethyl tungsten (W(CH₃)₆). bis(tert-butylimino) bis(dimethylamino) tungsten (C₁₂H₃₀N₄W), and tungsten hexacarbonyl (W(CO)₆).

Where the cobalt nitride layer is exposed to the metal-containing precursor in a soak process, the soak can be performed for any suitable length of time. In some examples, at 312, the soak can be performed for a duration between 1 and 60 seconds. In other examples, soak durations outside of this range can be used. Further, in some examples, a soak can be performed at a processing chamber pressure within a range of between 1 and 6 Torr. In other examples, a pressure outside this range can be used. In some examples, an inert gas is flowed with the metal-containing precursor. In other examples, an inert gas is omitted. Additionally, in some examples, a soak can be performed at a substrate temperature within a range of 200° C. to 450° C. In other examples, a substrate temperature outside this range can be used. Processing times and conditions can be controlled to achieve a desired thickness of the intermetal nitride phase. In some examples, the intermetal nitride phase comprises a thickness within a range of 3 to 20 Å. In other examples, the intermetal nitride phase comprises a thickness outside of this range.

Continuing, method 300 further comprises, at step 314, depositing a dielectric etch stop layer onto the intermetal nitride phase of the metal nitride layer. In some examples, as indicated at 316, method 300 comprises depositing a low-k dielectric etch stop layer. Suitable examples include dielectric materials that comprise a k which is less than or equal to 3.9. In some such examples, as indicated at 318, a silicon carbon nitride etch stop layer can deposited. Other example low-k dielectric etch stop layers include fluorine-doped silicon oxides, silicon oxycarbide, boron nitride, and boron carbon nitride. Further, any suitable method can be used to deposit the dielectric etch stop layer. Examples include chemical vapor deposition and atomic layer deposition.

At 320, method 300 optionally comprises annealing the substrate. Annealing can be performed to relieve stress and/or reduce defects in silicon or other materials, for example. Due to the intermetal nitride phase formed at 304, void formation is inhibited during annealing at 320. By avoiding void formation, method 300 can help avoid loss of adhesion between the metal nitride layer and the dielectric etch stop layer.

FIG. 4 shows an example processing tool 400 for exposing a substrate to an organometallic chemical in a soak process. Processing tool 400 is configured to deliver one or more gas-phase metal-containing precursors to expose a substrate to the gas-phase metal-containing precursor(s). In some examples, processing tool 400 can be configured as a thermal CVD tool.

Processing tool 400 comprises a processing chamber 402 and a substrate support 404 within the processing chamber. Substrate support 404 is configured to support a substrate 406 disposed within processing chamber 402. Substrate support 404 includes a substrate heater 408. In other examples, a heater can be omitted, or can be located elsewhere within processing chamber 402.

Processing tool 400 further comprises a showerhead 410 and flow control hardware 412. In other examples, a processing tool can comprise a nozzle or other apparatus for introducing gas into processing chamber 402, as opposed to or in addition to a showerhead.

Flow control hardware 412 connects a metal-containing precursor source 420 and an inert gas source 422 to processing chamber 402. Metal-containing precursor source 420 can comprise any suitable metal-containing precursor chemical that can be delivered to a processing chamber in a gas phase and that can form an intermetal nitride layer with a cobalt nitride film that inhibits cobalt mobility. Example metal-containing precursors include organoaluminum precursors, such as trimethylaluminum, triethylaluminum, and triisobutylaluminum. Other example organoaluminum precursors include dimethylaluminum chloride, diethylaluminum chloride, and diisobutylaluminum hydride. Example metal-containing precursors include aluminum halides, such as aluminum chloride, aluminum bromide, and aluminum iodide. Further examples of metal-containing chemicals further include diethylberyllium (Be(C₂H₅)₂), dimethyl magnesium ((CH₃)₂Mg), diethylmagnesium ((C₂H₅)₂Mg), tetrabenzyl titanium ((C₆H₅)₄Ti), titanium tetrachloride (TiCl₄), titanium isopropoxide (Ti(OCH(CH₃)₂)₄), tungsten hexafluoride (WF₆), tungsten hexachloride (WCl₆), hexamethyl tungsten (W(CH₃)₆), bis(tert-butylimino) bis(dimethylamino) tungsten (C₁₂H₃₀N₄W), and tungsten hexacarbonyl (W(CO)₆).

In some examples, the metal-containing chemical can be in condensed phase. In some such examples, metal-containing precursor source 420 can comprise a heater to volatize the metal-containing chemical. In some such examples, the metal-containing chemical can have a vapor pressure when in the condensed phase. In such examples, a flow-over-vapor (FOV) delivery system can be used. Such a FOV delivery system can comprise an ampoule in which the metal-containing chemical is disposed. A FOV delivery system can further comprise a gas inlet for flowing a carrier gas into the ampoule. A FOV delivery system can further comprise a gas outlet for delivering the carrier gas with metal-containing chemical vapor into processing chamber 402.

Inert gas source 422 can comprise any suitable inert gas. Examples include helium, neon, argon, krypton, xenon, and nitrogen. Inert gas source 422 can be used to provide a flow of a carrier gas for the metal-containing precursor source. Inert gas source 422 can also be used to purge processing chamber 402 after performing a process of exposing cobalt nitride layer to a metal-containing precursor.

Flow control hardware 412 can be controlled to flow gas from metal-containing precursor source 420 and inert gas source 422 into processing chamber 402 through showerhead 410. Flow control hardware 412 can comprise one or more valves controllable to place a selected gas source or selected gas sources in fluid connection with showerhead 410. Flow control hardware 412 also can comprise one or more mass flow controllers or other controllers for controlling a mass flow rate of gas.

Processing tool 400 further comprises an exhaust system 432. Exhaust system 432 is configured to receive gases outflowing from processing chamber 402. In some examples, exhaust system 432 is configured to actively remove gas from processing chamber 402 and/or apply a partial vacuum. Exhaust system 432 can comprise any suitable hardware, including one or pumps. Controller 450 is operatively coupled to substrate heater 408, flow control hardware 412, and exhaust system 432. Controller 450 is configured to control various functions of processing tool 400 to cause processing tool 400 to form an intermetal nitride phase in a cobalt nitride layer of substrate 406. For example, controller 450 is configured to operate substrate heater 408 to heat a substrate. Controller 450 is also configured to operate flow control hardware 412 to flow a selected gas of mixture of gases at a selected flow rate into processing chamber 402. For example, controller 450 can be configured to flow a metal-containing precursor from metal-containing precursor source 420 into processing chamber 402 to expose substrate 406 to the metal-containing precursor. Controller 450 is further configured to operate exhaust system 432 to remove gases from processing chamber 402. Controller 450 can, for example, control a purging of processing chamber 402 by controlling flow control hardware 412 to flow inert gas into processing chamber 402 and controlling exhaust system 432 to remove gas from processing chamber 402. Controller 450 can comprise any suitable computing system. Example computing systems are described in more detail below with reference to FIG. 5.

In other examples, any other suitable processing tool can be used to expose a substrate to a gas-phase metal-containing precursor. Example processing tools include PECVD tools, thermal ALD tools, or plasma-enhanced ALD (PEALD) tools. A PECVD tool or PEALD tool can be configured for remote plasma or direct plasma in various examples. In such examples, use of a plasma can help activate a gas-phase metal-containing precursor to facilitate incorporation of metal into a cobalt nitride layer.

Thus, the disclosed examples provide for forming an intermetal nitride phase to inhibit cobalt mobility in a cobalt nitride layer during an annealing process. Such an intermetal nitride phase can help prevent voids in the cobalt nitride layer. By avoiding voids, the disclose examples can help avoid delamination of a low-k etch stop layer, and further can avoid and defects that can affect device performance.

In some embodiments, the methods and processes described herein can be tied to a computing system of one or more computing devices. In particular, such methods and processes can be implemented as a computer-application program or service, an application-programming interface (API), a library, and/or other computer-program product.

FIG. 5 schematically shows a non-limiting embodiment of a computing system 500 that can enact one or more of the methods and processes described above. Computing system 500 is shown in simplified form. Computing system 500 can take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and/or network accessible server computers. Controller 450 is an example of computing system 500.

Computing system 500 includes a logic machine 502 and a storage machine 504. Computing system 500 can optionally include a display subsystem 506, input subsystem 508, communication subsystem 510, and/or other components not shown in FIG. 5.

Logic machine 502 includes one or more physical devices configured to execute instructions. For example, the logic machine can be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions can be implemented to perform a task, implement a data type, transform the state of one or more components, achieve a technical effect, or otherwise arrive at a desired result.

The logic machine can include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine can include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic machine can be single-core or multi-core, and the instructions executed thereon can be configured for sequential, parallel, and/or distributed processing. Individual components of the logic machine optionally can be distributed among two or more separate devices, which can be remotely located and/or configured for coordinated processing. Aspects of the logic machine can be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

Storage machine 504 includes one or more physical devices configured to hold instructions 512 executable by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage machine 504 can be transformed—e.g., to hold different data.

Storage machine 504 can include removable and/or built-in devices. Storage machine 504 can include optical memory (e.g., CD, DVD, HD-DVD, Blu-Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and/or magnetic memory (e.g., hard-disk drive, floppy-disk drive, tape drive, MRAM, etc.), among others. Storage machine 504 can include volatile, nonvolatile, dynamic, static, read/write, read-only, random-access, sequential-access, location-addressable, file-addressable, and/or content-addressable devices.

It will be appreciated that storage machine 504 includes one or more physical devices. However, aspects of the instructions described herein alternatively can be propagated by a communication medium (e.g., an electromagnetic signal, an optical signal, etc.) that is not held by a physical device for a finite duration.

Aspects of logic machine 502 and storage machine 504 can be integrated together into one or more hardware-logic components. Such hardware-logic components can include field-programmable gate arrays (FPGAs), program- and application-specific integrated circuits (PASIC/ASICs), program- and application-specific standard products (PSSP/ASSPs), system-on-a-chip (SOC), and complex programmable logic devices (CPLDs), for example.

When included, display subsystem 506 can be used to present a visual representation of data held by storage machine 504. This visual representation can take the form of a graphical user interface (GUI). As the herein described methods and processes change the data held by the storage machine, and thus transform the state of the storage machine, the state of display subsystem 506 can likewise be transformed to visually represent changes in the underlying data. Display subsystem 506 can include one or more display devices utilizing virtually any type of technology. Such display devices can be combined with logic machine 502 and/or storage machine 504 in a shared enclosure, or such display devices can be peripheral display devices.

When included, input subsystem 508 can comprise or interface with one or more user-input devices such as a keyboard, mouse, or touch screen. In some embodiments, the input subsystem can comprise or interface with selected natural user input (NUI) componentry. Such componentry can be integrated or peripheral, and the transduction and/or processing of input actions can be handled on- or off-board. Example NUI componentry can include a microphone for speech and/or voice recognition, and an infrared, color, stereoscopic, and/or depth camera for machine vision and/or gesture recognition.

When included, communication subsystem 510 can be configured to communicatively couple computing system 500 with one or more other computing devices. Communication subsystem 510 can include wired and/or wireless communication devices compatible with one or more different communication protocols. As non-limiting examples, the communication subsystem can be configured for communication via a wireless telephone network, or a wired or wireless local- or wide-area network. In some embodiments, the communication subsystem can allow computing system 500 to send and/or receive messages to and/or from other devices via a network such as the Internet.

It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. A method for processing a substrate, the method comprising:

introducing a gas-phase metal-containing precursor into a processing chamber to expose a metal nitride layer on a substrate in the processing chamber to the gas-phase metal-containing precursor, thereby forming an intermetal nitride phase in at least a surface region of the metal nitride layer; and

depositing a dielectric etch stop layer onto the metal nitride layer.

2. The method of claim 1, wherein the metal nitride layer comprises a cobalt nitride layer.

3. The method of claim 2, wherein exposing the cobalt nitride layer to the gas-phase metal-containing precursor comprises exposing the cobalt nitride layer to an organoaluminum precursor.

4. The method of claim 3, wherein exposing the cobalt nitride layer to the organoaluminum precursor comprises exposing the cobalt nitride layer to one or more of trimethylaluminum, triethylaluminum, or triisobutylaluminum.

5. The method of claim 2, wherein the gas-phase metal-containing precursor comprises an organometallic chemical comprising aluminum, beryllium, magnesium, titanium, or tungsten.

6. The method of claim 2, further comprising performing a pretreatment to remove at least some oxide from the cobalt nitride layer before introducing the gas-phase metal-containing precursor into the processing chamber.

7. The method of claim 2, wherein the dielectric etch stop layer comprises silicon carbon nitride.

8. The method of claim 2, wherein exposing the cobalt nitride layer to the gas-phase metal-containing precursor comprises exposing the cobalt nitride layer to the gas-phase metal-containing precursor for a duration of 1 to 60 seconds.

9. The method of claim 2, further comprising annealing the substrate.

10. A method for processing a substrate, the method comprising:

exposing a cobalt nitride layer on the substrate to aluminum, thereby forming a cobalt-aluminum nitride phase in at least a surface region of the cobalt nitride layer; and

depositing a dielectric etch stop layer onto the cobalt-aluminum nitride phase of the cobalt nitride layer.

11. The method of claim 10, further comprising performing a pretreatment to remove at least some cobalt oxide from the cobalt nitride layer before exposing the cobalt nitride layer to aluminum.

12. The method of claim 10, wherein exposing the cobalt nitride layer to the aluminum comprises exposing the cobalt nitride layer to an organoaluminum precursor comprising g one or more of trimethylaluminum, triethylaluminum, or triisobutylaluminum.

13. The method of claim 12, wherein exposing the cobalt nitride layer to the organoaluminum precursor comprises exposing the cobalt nitride layer to the organoaluminum precursor for a duration in a range of 1 to 60 seconds.

14. The method of claim 10, wherein exposing the cobalt nitride layer to the aluminum comprises exposing the cobalt nitride layer to an aluminum halide.

15. The method of claim 10, wherein depositing the dielectric etch stop layer comprises depositing a low-dielectric constant (low-k) dielectric etch stop layer. I

16. The method of claim 15, wherein depositing the low-k dielectric etch stop layer comprises depositing silicon carbon nitride.

17. The method of claim 10, further comprising annealing the substrate.

18. A substrate structure, comprising:

a metal line comprising a conductor;

a dielectric etch stop layer; and

a cobalt nitride layer disposed between the metal line and the dielectric etch stop layer, at least a portion of the cobalt nitride layer adjacent to an interface with the dielectric etch stop layer comprising an intermetal nitride phase.

19. The substrate structure of claim 18, wherein the intermetal nitride phase comprises cobalt-aluminum nitride.

20. The substrate structure of claim 18, wherein the dielectric etch stop layer comprises silicon carbon nitride.