US20220325410A1

US20220325410A1 - Gap fill methods using catalyzed deposition

Info

Publication number: US20220325410A1
Application number: US17/847,351
Authority: US
Inventors: Byunghoon Yoon; Liqi Wu; Joung Joo Lee; Kai Wu; Xi CEN; Wei Lei; Sang Ho Yu; Seshadri Ganguli
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2020-03-11
Filing date: 2022-06-23
Publication date: 2022-10-13
Also published as: KR20220116024A; JP2023515751A; US20210285102A1; CN115088064A; TW202200822A; WO2021183728A1

Abstract

Methods of depositing a metal film are discussed. A metal film is formed on the bottom of feature having a metal bottom and dielectric sidewalls. Formation of the metal film comprises exposure to a metal precursor and an alkyl halide catalyst while the substrate is maintained at a deposition temperature. The metal precursor has a decomposition temperature above the deposition temperature. The alkyl halide comprises carbon and halogen, and the halogen comprises bromine or iodine.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No. 17/198,576, filed on Mar. 11, 2021, which claims priority to U.S. Provisional Application No. 62/988,091, filed Mar. 11, 2020, the entire disclosures of which are hereby incorporated by reference herein.

TECHNICAL FIELD

Embodiments of the disclosure generally relate to methods for depositing metal films. Some embodiments of the disclosure are directed to methods for depositing metal films. Some embodiments of the disclosure relate to the selective deposition of metal films. Some embodiments of the disclosure control the location and/or rate of deposition through the use of plasma and/or thermal exposure conditions.

BACKGROUND

The semiconductor industry continues to strive for continuous device miniaturization that is driven by the need for mobile and high-performance systems in emerging industries such as autonomous vehicles, virtual reality, and future mobile devices. To accomplish this feat, new, high-performance materials are needed to circumvent inherent engineering, chemical and physics issues encountered in the rapid reduction of features in microelectronic devices.
Ruthenium is a new proposed material for integration owing to its high melting point (ability to withstand high current densities), exceptional density, and ability to conduct electrical current. Ruthenium and ruthenium containing thin films have attractive material and conductive properties. Ruthenium films have been proposed for applications ranging from front end to back end parts of semiconductor and microelectronic devices.
Thin-films of ruthenium would ideally be deposited using thin-film deposition techniques such as Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) owing to their inherent ability to deposit material in a high-throughput and precise fashion.
Yet deposited ruthenium films often differ from bulk ruthenium materials. There is particular challenge in depositing ruthenium films with high purity (>99 atomic % of Ru), especially as gap fill material. Previous solutions utilizing oxygen reactants produced films with greater roughness than bulk materials. Similarly, hydrogen reactants produced greater impurities which required a subsequent annealing step for removal. Finally, plasma deposition processes were unable to deposit gap fill materials without creating a seam and potentially damaging the underlying substrate.
In the current state of the art, structures are filled by CVD or electrochemical plating (ECP) processes. In CVD processes where the deposition happens all over the structure, a void is usually formed when the films merge due to roughness, leaving a seam in the gap. ECP processes are restricted by size and whether a process for the required material exists.
Therefore there is a need for methods and materials for depositing high purity conformal ruthenium films as gap fill. There is also a need for methods and materials for depositing ruthenium films as gap fill without seams or voids.
Additionally, as the design of semiconductor devices evolve, precision material manufacturing in the semiconductor industry has entered an era of atomic scale dimensions. At the atomic scale, with only tens of atoms at stake, there is little margin for error. This unprecedented challenge demands new material processing techniques which have atomic level precision. However, increasing the complexity of the process flow required in atomic scale device manufacturing can significantly lower throughput and increase the cost of manufacturing.
Selective deposition technologies offer the potential for chemically-selective atomic-layer precision in semiconductor film patterning. Selective deposition also offers the potential for simpler process flows by eliminating lithography or other processes.
Selective deposition of materials can be accomplished in a variety of ways. For instance, some processes may have inherent selectivity to surfaces based on their surface chemistry. These processes are fairly rare and usually need to have surfaces with drastically different surface energies, such as metals and dielectrics.
Therefore there is a need for methods of selectively depositing metal films on metallic surfaces over dielectric surfaces, or vice versa.
Further, current devices use tungsten films for memory and logic applications. Deposition of tungsten films is frequently performed at relatively high temperatures which can be limited by the thermal budget of the device being formed. Tungsten films are often deposited using fluorine containing compounds. Fluorine is generally not desirable in the deposition process as there can be reactions and adverse effects. To prevent fluorine from reacting with the underlying layers, a relatively thick barrier layer is used. The barrier layer deposition decreases thermal budget and throughput.
Therefore there is a need in the art for conductive materials that do not use fluorine and/or can be deposited at low temperatures.
Additionally, during middle-of-line (MOL) processes, a minimum via resistance for the MOL structures are targeted. A liner material is often required to improve adhesion of metals (e.g., ruthenium) to dielectric materials to pass post-processing steps such as chemical-mechanical planarization (CMP). However, the presence of the liner adds to the via resistance. Therefore, there is a need in the art for gap fill processes for MOL applications with decreased via resistance.

SUMMARY

One or more embodiments of the disclosure are directed to metal deposition methods. A substrate having at least one feature comprising a bottom and sidewalls is exposed to alternating pulses of a metal precursor and an alkyl halide catalyst. The substrate is maintained at a deposition temperature to form a metal film on the bottom of the feature. The bottom of the feature comprises a metal and the sidewalls of the feature comprise a dielectric. The metal precursor has a decomposition temperature above the deposition temperature. The alkyl halide comprises carbon and halogen, and the halogen comprises bromine or iodine.
Additional embodiments of the disclosure are directed to methods of forming a seam-free gap fill. A second metal film is deposited in a feature on a substrate to partially fill the feature with the second metal film. The feature comprises a bottom and at least one sidewall. The bottom comprises a first metal and the at least one sidewall comprises a dielectric. The second metal film is formed selectively on the bottom relative to the at least one sidewall and has a top surface below a top surface of the dielectric. A liner is deposited on the sidewall of the feature above the second metal film. The feature is filled with the second metal film to cover the liner and the top surface of the dielectric. The second metal film and at least some of the liner are removed from the top surface of the dielectric and at least some of the dielectric to form a seam-free gap fill.
Further embodiments of the disclosure are directed to methods of forming a seam-free gap fill. The methods comprise: (a) optionally cleaning a surface of a first metal at a bottom of a feature in a substrate, the feature comprising at least one dielectric sidewall; (b) selectively depositing a ruthenium film in the feature on first metal relative the dielectric sidewall, the ruthenium film partially filling the feature so that a top surface of the ruthenium film is below a top surface of the dielectric; (c) optionally, selectively forming a blocking layer on the top surface of the ruthenium film; (d) forming a conformal liner on the dielectric sidewall and the top surface of the dielectric, the conformal liner substantially not forming on the top surface of the ruthenium film; (e) optionally removing the blocking layer from the top surface of the ruthenium film; (f) filling the feature with the ruthenium film to cover the conformal liner on the dielectric sidewall and the top surface of the dielectric; (g) annealing the ruthenium film; and (h) removing a portion of the ruthenium film and the dielectric, and at least some of the liner to form a ruthenium seam-free gap fill.

BRIEF DESCRIPTION OF THE DRAWING

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIG. 1 shows a schematic view of a processing platform in accordance with one or more embodiment of the disclosure;

FIG. 2 shows a cross-sectional view of a batch processing chamber in accordance with one or more embodiment of the disclosure;

FIG. 3 shows a partial perspective view of a batch processing chamber in accordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a batch processing chamber in accordance with one or more embodiment of the disclosure;

FIG. 5 shows a schematic view of a portion of a wedge shaped gas distribution assembly for use in a batch processing chamber in accordance with one or more embodiment of the disclosure;

FIG. 6 shows a schematic view of a batch processing chamber in accordance with one or more embodiment of the disclosure;

FIG. 7 illustrates an exemplary process sequence for the formation of a metal layer using a two pulse cyclical deposition technique according to one or more embodiment of the disclosure;

FIG. 8 illustrates an exemplary process sequence for the formation of a ruthenium layer according to one or more embodiment of the disclosure;

FIG. 9 shows a cross-sectional view of an exemplary substrate in accordance with one or more embodiment of the disclosure;

FIGS. 10A-10D illustrate an exemplary substrate during processing according to one or more embodiment of the disclosure; and

FIG. 11 illustrates an exemplary method for seam-free gap filling according to one or more embodiment of the disclosure.

In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process routines set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.
A “substrate”, “substrate surface”, or the like, as used herein, refers to any substrate or material surface formed on a substrate upon which processing is performed. For example, a substrate surface on which processing can be performed include, but are not limited to, materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon doped silicon oxides, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor wafers. Substrates may be exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate (or otherwise generate or graft target chemical moieties to impart chemical functionality), anneal and/or bake the substrate surface. In addition to processing directly on the surface of the substrate itself, in the present disclosure, any of the film processing steps disclosed may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term “substrate surface” is intended to include such underlayer as the context indicates. Thus for example, where a film/layer or partial film/layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface. What a given substrate surface comprises will depend on what materials are to be deposited, as well as the particular chemistry used.
“Atomic layer deposition” or “cyclical deposition” as used herein refers to the sequential exposure of two or more reactive compounds to deposit a layer of material on a substrate surface. As used in this specification and the appended claims, the terms “reactive compound”, “reactive gas”, “reactive species”, “precursor”, “process gas” and the like are used interchangeably to mean a substance with a species capable of reacting with the substrate surface or material on the substrate surface in a surface reaction (e.g., chemisorption, oxidation, reduction). The substrate, or portion of the substrate, is exposed separately to the two or more reactive compounds which are introduced into a reaction zone of a processing chamber. In a time-domain ALD process, exposure to each reactive compound is separated by a time delay to allow each compound to adhere and/or react on the substrate surface and then be purged from the processing chamber. These reactive compounds are said to be exposed to the substrate sequentially. In a spatial ALD process, different portions of the substrate surface, or material on the substrate surface, are exposed simultaneously to the two or more reactive compounds so that any given point on the substrate is substantially not exposed to more than one reactive compound simultaneously. As used in this specification and the appended claims, the term “substantially” used in this respect means, as will be understood by those skilled in the art, that there is the possibility that a small portion of the substrate may be exposed to multiple reactive gases simultaneously due to diffusion, and that the simultaneous exposure is unintended.
In one aspect of a time-domain ALD process, a first reactive gas (i.e., a first precursor or compound A) is pulsed into the reaction zone followed by a first time delay. Next, a second precursor or compound B is pulsed into the reaction zone followed by a second delay. During each time delay, a purge gas, such as argon, is introduced into the processing chamber to purge the reaction zone or otherwise remove any residual reactive compound or reaction by-products from the reaction zone. Alternatively, the purge gas may flow continuously throughout the deposition process so that only the purge gas flows during the time delay between pulses of reactive compounds. The reactive compounds are alternatively pulsed until a desired film or film thickness is formed on the substrate surface. In either scenario, the ALD process of pulsing compound A, purge gas, compound B and purge gas is a cycle. A cycle can start with either compound A or compound B and continue the respective order of the cycle until achieving a film with the predetermined thickness.
In an embodiment of a spatial ALD process, a first reactive gas and second reactive gas (e.g., metal precursor gas) are delivered simultaneously to the reaction zone but are separated by an inert gas curtain and/or a vacuum curtain. The substrate is moved relative to the gas delivery apparatus so that any given point on the substrate is exposed to the first reactive gas and the second reactive gas.
As used in this specification and the appended claims, the terms “precursor”, “reactant”, “reactive gas” and the like are used interchangeably to refer to any gaseous species that can react with the substrate surface.
Some embodiments of the disclosure are directed to processes that use a reaction chamber with multiple gas ports that can be used for introduction of different chemicals or plasma gases. Spatially, these gas ports (also referred to as channels) are separated by inert purging gases and/or vacuum pumping holes to create a gas curtain that minimizes or eliminates mixing of gases from different gas ports to avoid unwanted gas phase reactions. Wafers moving through these different spatially separated ports get sequential and multiple surface exposures to different chemical or plasma environment so that layer by layer film growth in spatial ALD mode or surface etching process occur. In some embodiments, the processing chamber has modular architectures on gas distribution components and each modular component has independent parameter control (e.g., RF or gas flow) to provide flexibility to control, for example, gas flow and/or RF exposure.
Some embodiments of the disclosure provide methods for depositing a high purity metal film. The methods of various embodiments use atomic layer deposition (ALD) to provide pure or nearly pure metal films. While exemplary embodiments of this disclosure refer to the deposition of ruthenium, it is conceived that the principles of this disclosure enable the deposition of highly pure metal films regardless of metal.
Some embodiments of the disclosure provide methods of selectively depositing metal films on a metal surface over a dielectric surface. Some embodiments of the disclosure provide methods of selectively depositing metal films on a dielectric surface over a metal surface. As used in this specification and the appended claims, the term “selectively depositing a film on one surface over another surface”, and the like, means that a first amount of the film is deposited on the first surface and a second amount of film is deposited on the second surface, where the second amount of film is less than the first amount of film, or no film is deposited on the second surface.
The term “over” used in this regard does not imply a physical orientation of one surface on top of another surface, rather a relationship of the thermodynamic or kinetic properties of the chemical reaction with one surface relative to the other surface. For example, selectively depositing a metal film onto a metal surface over a dielectric surface means that the metal film deposits on the metal surface and less or no metal film deposits on the dielectric surface; or that the formation of a metal film on the metal surface is thermodynamically or kinetically favorable relative to the formation of a metal film on the dielectric surface.
The selectivity of a deposition process is generally expressed as a multiple of growth rate. For example, if one surface is grown (or deposited on) 25 times faster than a different surface, the process would be described as having a selectivity of 25:1. In this regard, higher ratios indicate more selective processes.
Some embodiments of the disclosure advantageously provide methods for depositing metal films with high purity. Accordingly, these highly pure films exhibit similar properties to their associated bulk metallic materials. For example, some embodiments of this disclosure provide ruthenium films which are smoother and have lower resistance than ruthenium films deposited by conventional oxygen or hydrogen reactant processes. Some embodiments of this disclosure advantageously provide metal films which conformally fill gaps without a seam.
Some embodiments of the disclosure advantageously provide for the selective deposition of metal films with high purity on metallic surfaces over dielectric surfaces. For example, selectively depositing metal (e.g., ruthenium) on copper over dielectrics advantageously provides copper capping layers without additional etch or lithography steps. Additionally, selective deposition may also enable bottom-up gapfill for features (e.g., trenches, vias) with metal contacts at the bottom and dielectric sidewalls.
Some embodiments of the disclosure advantageously provide for the selective deposition of metal films with high purity on dielectric surfaces over metallic surfaces. For example, selectively depositing metals over dielectrics advantageously provides metal layers on barriers or other dielectrics in back end applications.
Some embodiments of the disclosure utilize a spatial ALD process which is performed on a processing platform as disclosed herein. Referring to the Figures, FIG. 1 shows a processing platform 100 in accordance with one or more embodiment of the disclosure. The embodiment shown in FIG. 1 is merely representative of one possible configuration and should not be taken as limiting the scope of the disclosure. For example, in some embodiments, the processing platform 100 has different numbers of process chambers, buffer chambers and robot configurations.
The processing platform 100 includes a central transfer station 110 which has a plurality of sides 111, 112, 113, 114, 115, 116. The central transfer station 110 shown has a first side 111, a second side 112, a third side 113, a fourth side 114, a fifth side 115 and a sixth side 116. Although six sides are shown, those skilled in the art will understand that there can be any suitable number of sides to the central transfer station 110 depending on, for example, the overall configuration of the processing platform 100.
The transfer station 110 has a robot 117 positioned therein. The robot 117 can be any suitable robot capable of moving a wafer during processing. In some embodiments, the robot 117 has a first arm 118 and a second arm 119. The first arm 118 and second arm 119 can be moved independently of the other arm. The first arm 118 and second arm 119 can move in the x-y plane and/or along the z-axis. In some embodiments, the robot 117 includes a third arm or a fourth arm (not shown). Each of the arms can move independently of other arms.
A first batch processing chamber 120 can be connected to a first side 111 of the central transfer station 110. The first batch processing chamber 120 can be configured to process x wafers at a time for a batch time. In some embodiments, the first batch processing chamber 120 can be configured to process in the range of about four (x=4) to about 12 (x=12) wafers at the same time. In some embodiments, the first batch processing chamber 120 is configured to process six (x=6) wafers at the same time. As will be understood by the skilled artisan, while the first batch processing chamber 120 can process multiple wafers between loading/unloading of an individual wafer, each wafer may be subjected to different process conditions at any given time. For example, a spatial atomic layer deposition chamber, like that shown in FIGS. 2 through 6, expose the wafers to different process conditions in different processing regions so that as a wafer is moved through each of the regions, the process is completed.
FIG. 2 shows a cross-section of a processing chamber 200 including a gas distribution assembly 220, also referred to as injectors or an injector assembly, and a susceptor assembly 240. The gas distribution assembly 220 is any type of gas delivery device used in a processing chamber. The gas distribution assembly 220 includes a front surface 221 which faces the susceptor assembly 240. The front surface 221 can have any number or variety of openings to deliver a flow of gases toward the susceptor assembly 240. The gas distribution assembly 220 also includes an outer peripheral edge 224 which in the embodiments shown, is substantially round.
The specific type of gas distribution assembly 220 used can vary depending on the particular process being used. Embodiments of the disclosure can be used with any type of processing system where the gap between the susceptor and the gas distribution assembly is controlled. While various types of gas distribution assemblies can be employed (e.g., showerheads), embodiments of the disclosure may be particularly useful with spatial gas distribution assemblies which have a plurality of substantially parallel gas channels. As used in this specification and the appended claims, the term “substantially parallel” means that the elongate axis of the gas channels extend in the same general direction. There can be slight imperfections in the parallelism of the gas channels. In a binary reaction, the plurality of substantially parallel gas channels can include at least one first reactive gas A channel, at least one second reactive gas B channel, at least one purge gas P channel and/or at least one vacuum V channel. The gases flowing from the first reactive gas A channel(s), the second reactive gas B channel(s) and the purge gas P channel(s) are directed toward the top surface of the wafer. Some of the gas flow moves horizontally across the surface of the wafer and out of the process region through the purge gas P channel(s). A substrate moving from one end of the gas distribution assembly to the other end will be exposed to each of the process gases in turn, forming a layer on the substrate surface.
In some embodiments, the gas distribution assembly 220 is a rigid stationary body made of a single injector unit. In one or more embodiments, the gas distribution assembly 220 is made up of a plurality of individual sectors (e.g., injector units 222), as shown in FIG. 3. Either a single piece body or a multi-sector body can be used with the various embodiments of the disclosure described.
A susceptor assembly 240 is positioned beneath the gas distribution assembly 220. The susceptor assembly 240 includes a top surface 241 and at least one recess 242 in the top surface 241. The susceptor assembly 240 also has a bottom surface 243 and an edge 244. The at least one recess 242 can be any suitable shape and size depending on the shape and size of the substrates 60 being processed. In the embodiment shown in FIG. 2, the recess 242 has a flat bottom to support the bottom of the wafer; however, the bottom of the recess can vary. In some embodiments, the recess has step regions around the outer peripheral edge of the recess which are sized to support the outer peripheral edge of the wafer. The amount of the outer peripheral edge of the wafer that is supported by the steps can vary depending on, for example, the thickness of the wafer and the presence of features already present on the back side of the wafer.
In some embodiments, as shown in FIG. 2, the recess 242 in the top surface 241 of the susceptor assembly 240 is sized so that a substrate 60 supported in the recess 242 has a top surface 61 substantially coplanar with the top surface 241 of the susceptor 240. As used in this specification and the appended claims, the term “substantially coplanar” means that the top surface of the wafer and the top surface of the susceptor assembly are coplanar within ±0.2 mm. In some embodiments, the top surfaces are coplanar within 0.5 mm, ±0.4 mm, ±0.35 mm, ±0.30 mm, ±0.25 mm, ±0.20 mm, ±0.15 mm, ±0.10 mm or ±0.05 mm.
The susceptor assembly 240 of FIG. 2 includes a support post 260 which is capable of lifting, lowering and rotating the susceptor assembly 240. The susceptor assembly may include a heater, or gas lines, or electrical components within the center of the support post 260. The support post 260 may be the primary means of increasing or decreasing the gap between the susceptor assembly 240 and the gas distribution assembly 220, moving the susceptor assembly 240 into proper position. The susceptor assembly 240 may also include fine tuning actuators 262 which can make micro-adjustments to susceptor assembly 240 to create a predetermined gap 270 between the susceptor assembly 240 and the gas distribution assembly 220.
In some embodiments, the gap 270 distance is in the range of about 0.1 mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, or in the range of about 0.1 mm to about 2.0 mm, or in the range of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or in the range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the range of about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm to about 1.1 mm, or about 1 mm.
The processing chamber 200 shown in the Figures is a carousel-type chamber in which the susceptor assembly 240 can hold a plurality of substrates 60. As shown in FIG. 3, the gas distribution assembly 220 may include a plurality of separate injector units 222, each injector unit 222 being capable of depositing a film on the wafer, as the wafer is moved beneath the injector unit. Two pie-shaped injector units 222 are shown positioned on approximately opposite sides of and above the susceptor assembly 240. This number of injector units 222 is shown for illustrative purposes only. It will be understood that more or less injector units 222 can be included. In some embodiments, there are a sufficient number of pie-shaped injector units 222 to form a shape conforming to the shape of the susceptor assembly 240. In some embodiments, each of the individual pie-shaped injector units 222 may be independently moved, removed and/or replaced without affecting any of the other injector units 222. For example, one segment may be raised to permit a robot to access the region between the susceptor assembly 240 and gas distribution assembly 220 to load/unload substrates 60.
Processing chambers having multiple gas injectors can be used to process multiple wafers simultaneously so that the wafers experience the same process flow. For example, as shown in FIG. 4, the processing chamber 200 has four gas injector assemblies and four substrates 60. At the outset of processing, the substrates 60 can be positioned between the gas distribution assemblies 220. Rotating 17 the susceptor assembly 240 by 45° will result in each substrate 60 which is between gas distribution assemblies 220 to be moved to a gas distribution assembly 220 for film deposition, as illustrated by the dotted circle under the gas distribution assemblies 220. An additional 45° rotation would move the substrates 60 away from the gas distribution assemblies 220. The number of substrates 60 and gas distribution assemblies 220 can be the same or different. In some embodiments, there are the same numbers of wafers being processed as there are gas distribution assemblies. In one or more embodiments, the number of wafers being processed are fraction of or an integer multiple of the number of gas distribution assemblies. For example, if there are four gas distribution assemblies, there are 4x wafers being processed, where x is an integer value greater than or equal to one. In an exemplary embodiment, the gas distribution assembly 220 includes eight process regions separated by gas curtains and the susceptor assembly 240 can hold six wafers.
The processing chamber 200 shown in FIG. 4 is merely representative of one possible configuration and should not be taken as limiting the scope of the disclosure. Here, the processing chamber 200 includes a plurality of gas distribution assemblies 220. In the embodiment shown, there are four gas distribution assemblies 220 (also called injector assemblies) evenly spaced about the processing chamber 200. The processing chamber 200 shown is octagonal; however, those skilled in the art will understand that this is one possible shape and should not be taken as limiting the scope of the disclosure. The gas distribution assemblies 220 shown are trapezoidal, but can be a single circular component or made up of a plurality of pie-shaped segments, like that shown in FIG. 3.
The embodiment shown in FIG. 4 includes a load lock chamber 280, or an auxiliary chamber like a buffer station. This chamber 280 is connected to a side of the processing chamber 200 to allow, for example the substrates (also referred to as substrates 60) to be loaded/unloaded from the processing chamber 200. A wafer robot may be positioned in the chamber 280 to move the substrate onto the susceptor.
Rotation of the carousel (e.g., the susceptor assembly 240) can be continuous or intermittent (discontinuous). In continuous processing, the wafers are constantly rotating so that they are exposed to each of the injectors in turn. In discontinuous processing, the wafers can be moved to the injector region and stopped, and then to the region 84 between the injectors and stopped. For example, the carousel can rotate so that the wafers move from an inter-injector region across the injector (or stop adjacent the injector) and on to the next inter-injector region where the carousel can pause again. Pausing between the injectors may provide time for additional processing routines between each layer deposition (e.g., exposure to plasma).
FIG. 5 shows a sector or portion of a gas distribution assembly 220, which may be referred to as an injector unit. The injector units 222 can be used individually or in combination with other injector units. For example, as shown in FIG. 6, four of the injector units 222 of FIG. 5 are combined to form a single gas distribution assembly 220. (The lines separating the four injector units are not shown for clarity.) While the injector unit 222 of FIG. 5 has both a first reactive gas port 225 and a second gas port 235 in addition to purge gas ports 255 and vacuum ports 245, an injector unit 222 does not need all of these components.
Referring to both FIGS. 5 and 6, a gas distribution assembly 220 in accordance with one or more embodiment may comprise a plurality of sectors (or injector units 222) with each sector being identical or different. The gas distribution assembly 220 is positioned within the processing chamber and comprises a plurality of elongate gas ports 225, 235, 245 in a front surface 221 of the gas distribution assembly 220. The plurality of elongate gas ports 225, 235, 245, 255 extend from an area adjacent the inner peripheral edge 223 toward an area adjacent the outer peripheral edge 224 of the gas distribution assembly 220. The plurality of gas ports shown include a first reactive gas port 225, a second gas port 235, a vacuum port 245 which surrounds each of the first reactive gas ports and the second reactive gas ports and a purge gas port 255.
With reference to the embodiments shown in FIG. 5 or 6, when stating that the ports extend from at least about an inner peripheral region to at least about an outer peripheral region, however, the ports can extend more than just radially from inner to outer regions. The ports can extend tangentially as vacuum port 245 surrounds reactive gas port 225 and reactive gas port 235. In the embodiment shown in FIGS. 5 and 6, the wedge shaped reactive gas ports 225, 235 are surrounded on all edges, including adjacent the inner peripheral region and outer peripheral region, by a vacuum port 245.
Referring to FIG. 5, as a substrate moves along path 227, each portion of the substrate surface is exposed to the various reactive gases. To follow the path 227, the substrate will be exposed to, or “see”, a purge gas port 255, a vacuum port 245, a first reactive gas port 225, a vacuum port 245, a purge gas port 255, a vacuum port 245, a second gas port 235 and a vacuum port 245. Thus, at the end of the path 227 shown in FIG. 5, the substrate has been exposed to the first reactive gas and the second reactive gas to form a layer. The injector unit 222 shown makes a quarter circle but could be larger or smaller. The gas distribution assembly 220 shown in FIG. 6 can be considered a combination of four of the injector units 222 of FIG. 3 connected in series.
The injector unit 222 of FIG. 5 shows a gas curtain 250 that separates the reactive gases. The term “gas curtain” is used to describe any combination of gas flows or vacuum that separate reactive gases from mixing. The gas curtain 250 shown in FIG. 5 comprises the portion of the vacuum port 245 next to the first reactive gas port 225, the purge gas port 255 in the middle and a portion of the vacuum port 245 next to the second gas port 235. This combination of gas flow and vacuum can be used to prevent or minimize gas phase reactions of the first reactive gas and the second reactive gas.
Referring to FIG. 6, the combination of gas flows and vacuum from the gas distribution assembly 220 form a separation into a plurality of process regions 350. The process regions are roughly defined around the individual gas ports 225, 235 with the gas curtain 250 between 350. The embodiment shown in FIG. 6 makes up eight separate process regions 350 with eight separate gas curtains 250 between. A processing chamber can have at least two process regions. In some embodiments, there are at least three, four, five, six, seven, eight, nine, 10, 11 or 12 process regions.
During processing a substrate may be exposed to more than one process region 350 at any given time. However, the portions that are exposed to the different process regions will have a gas curtain separating the two. For example, if the leading edge of a substrate enters a process region including the second gas port 235, a middle portion of the substrate will be under a gas curtain 250 and the trailing edge of the substrate will be in a process region including the first reactive gas port 225.
A factory interface (as shown in FIG. 4), which can be, for example, a load lock chamber 280, is shown connected to the processing chamber 200. A substrate 60 is shown superimposed over the gas distribution assembly 220 to provide a frame of reference. The substrate 60 may often sit on a susceptor assembly to be held near the front surface 221 of the gas distribution assembly 220. The substrate 60 is loaded via the factory interface into the processing chamber 200 onto a substrate support or susceptor assembly (see FIG. 4). The substrate 60 can be shown positioned within a process region because the substrate is located adjacent the first reactive gas port 225 and between two gas curtains 250 a, 250 b. Rotating the substrate 60 along path 227 will move the substrate counter-clockwise around the processing chamber 200. Thus, the substrate 60 will be exposed to the first process region 350 a through the eighth process region 350 h, including all process regions between.
Some embodiments of the disclosure are directed to a processing chamber 200 with a plurality of process regions 350 a-350 h with each process region separated from an adjacent region by a gas curtain 250. For example, the processing chamber shown in FIG. 6. The number of gas curtains and process regions within the processing chamber can be any suitable number depending on the arrangement of gas flows. The embodiment shown in FIG. 6 has eight gas curtains 250 and eight process regions 350 a-350 h.
Referring back to FIG. 1, the processing platform 100 includes a treatment chamber 140 connected to a second side 112 of the central transfer station 110. The treatment chamber 140 of some embodiments is configured to expose the wafers to a process to treat the wafers before and/or after processing in first batch processing chamber 120. The treatment chamber 140 of some embodiments comprises an annealing chamber. The annealing chamber can be a furnace annealing chamber or a rapid thermal annealing chamber, or a different chamber configured to hold a wafer at a predetermined temperature and pressure and provide a flow of gas to the chamber.
In some embodiments, the processing platform further comprises a second batch processing chamber 130 connected to a third side 113 of the central transfer station 110. The second batch processing chamber 130 can be configured similarly to the first batch processing chamber 120, or can be configured to perform a different process or to process different numbers of substrates.
The second batch processing chamber 130 can be the same as the first batch processing chamber 120 or different. In some embodiments, the first batch processing chamber 120 and the second batch processing chamber 130 are configured to perform the same process with the same number of wafers in the same batch time so that x (the number of wafers in the first batch processing chamber 120) and y (the number of wafers in the second batch processing chamber 130) are the same and the first batch time and second batch time (of the second batch processing chamber 130) are the same. In some embodiments, the first batch processing chamber 120 and the second batch processing chamber 130 are configured to have one or more of different numbers of wafers (x not equal to y), different batch times, or both.
In the embodiment shown in FIG. 1, the processing platform 100 includes a second treatment chamber 150 connected to a fourth side 114 of the central transfer station 110. The second treatment chamber 150 can be the same as the treatment chamber 140 or different.
The processing platform 100 can include a controller 195 connected to the robot 117 (the connection is not shown). The controller 195 can be configured to move wafers between the treatment chamber 140 and the first batch processing chamber 120 with a first arm 118 of the robot 117. In some embodiments, the controller 195 is also configured to move wafers between the second treatment chamber 150 and the second batch processing chamber 130 with a second arm 119 of the robot 117.
In some embodiments, the controller 195 is connected to the susceptor assembly 240 and the gas distribution assembly 220 of a processing chamber 200. The controller 195 can be configured to rotate 17 the susceptor assembly 240 about a central axis. The controller can also be configured to control the gas flows in the gas ports 225, 235, 245, 255. In some embodiments, the first reactive gas port 225 provides a flow of a metal precursor. In some embodiments, the second reactive gas port 235 provides a flow of a reactant. In some embodiments, other gas ports (not labelled) may provide a flow of a plasma. The first reactive gas port 225, the second reactive gas port 235 and the other reactive gas ports (not labelled) may be arranged in any processing order.
The processing platform 100 can also include a first buffer station 151 connected to a fifth side 115 of the central transfer station 110 and/or a second buffer station 152 connected to a sixth side 116 of the central transfer station 110. The first buffer station 151 and second buffer station 152 can perform the same or different functions. For example, the buffer stations may hold a cassette of wafers which are processed and returned to the original cassette, or the first buffer station 151 may hold unprocessed wafers which are moved to the second buffer station 152 after processing. In some embodiments, one or more of the buffer stations are configured to pre-treat, pre-heat or clean the wafers before and/or after processing.
In some embodiments, the controller 195 is configured to move wafers between the first buffer station 151 and one or more of the treatment chamber 140 and the first batch processing chamber 120 using the first arm 118 of the robot 117. In some embodiments, the controller 195 is configured to move wafers between the second buffer station 152 and one or more of the second treatment chamber 150 or the second batch processing chamber 130 using the second arm 119 of the robot 117.
The processing platform 100 may also include one or more slit valves 160 between the central transfer station 110 and any of the processing chambers. In the embodiment shown, there is a slit valve 160 between each of the processing chambers 120, 130, 140, 150 and the central transfer station 110. The slit valves 160 can open and close to isolate the environment within the processing chamber from the environment within the central transfer station 110. For example, if the processing chamber will generate plasma during processing, it may be helpful to close the slit valve for that processing chamber to prevent stray plasma from damaging the robot in the transfer station.
In some embodiments, the processing chambers are not readily removable from the central transfer station 110. To allow maintenance to be performed on any of the processing chambers, each of the processing chambers may further include a plurality of access doors 170 on sides of the processing chambers. The access doors 170 allow manual access to the processing chamber without removing the processing chamber from the central transfer station 110. In the embodiment shown, each side of each of the processing chamber, except the side connected to the transfer station, have an access door 170. The inclusion of so many access doors 170 can complicate the construction of the processing chambers employed because the hardware within the chambers would need to be configured to be accessible through the doors.
The processing platform of some embodiments includes a water box 180 connected to the central transfer station 110. The water box 180 can be configured to provide a coolant to any or all of the processing chambers. Although referred to as a “water” box, those skilled in the art will understand that any coolant can be used.
In some embodiments, the size of the processing platform 100 allows for the connection to house power through a single power connector 190. The single power connector 190 attaches to the processing platform 100 to provide power to each of the processing chambers and the central transfer station 110.
The processing platform 100 can be connected to a factory interface 102 to allow wafers or cassettes of wafers to be loaded into the processing platform 100. A robot 103 within the factory interface 102 can be moved the wafers or cassettes into and out of the buffer stations 151, 152. The wafers or cassettes can be moved within the processing platform 100 by the robot 117 in the central transfer station 110. In some embodiments, the factory interface 102 is a transfer station of another cluster tool.
In some embodiments, the processing platform 100 or first batch processing chamber 120 is connected to a controller. The controller can be the same controller 195 or a different controller. The controller can be coupled to the susceptor assembly and the gas distribution assembly of the first batch processing chamber 120 and has one or more configurations. The configurations can include, but are not limited to, a first configuration to rotate the susceptor assembly about the central axis, a second configuration to provide a flow of a metal precursor to a process region, a third configuration to provide a flow of a reactant to a process region, a fourth configuration to provide a plasma in a process region.
FIG. 7 depicts a generalized method for forming a metal film on a substrate in accordance with one or more embodiment of the disclosure. The method 700 generally begins at 702, where a substrate upon which a metal film is to be formed is provided and placed into a processing chamber. As used herein, a “substrate surface” refers to any substrate surface upon which a layer may be formed. The substrate surface may have one or more features formed therein, one or more layers formed thereon, and combinations thereof. The substrate (or substrate surface) may be pretreated prior to the deposition of the metal film, for example, by polishing, etching, reduction, oxidation, halogenation, hydroxylation, annealing, baking, or the like.
The substrate may be any substrate capable of having material deposited thereon, such as a silicon substrate, a III-V compound substrate, a silicon germanium (SiGe) substrate, an epi-substrate, a silicon-on-insulator (SOI) substrate, a display substrate such as a liquid crystal display (LCD), a plasma display, an electro luminescence (EL) lamp display, a solar array, solar panel, a light emitting diode (LED) substrate, a semiconductor wafer, or the like. In some embodiments, one or more additional layers may be disposed on the substrate such that the metal film may be, at least partially, formed thereon. For example, in some embodiments, a layer comprising a metal, a nitride, an oxide, or the like, or combinations thereof may be disposed on the substrate and may have the metal film formed upon such layer or layers.
At 703, the substrate is optionally exposed to a blocking compound. This process step is described more fully below and may be useful for controlling the selectivity of the deposition process on a substrate comprising both a metal surface and a dielectric surface.
At 704, a metal film is formed on the substrate. The metal film may be formed via a cyclical deposition process, such as atomic layer deposition (ALD), or the like. In some embodiments, the forming of a metal film via a cyclical deposition process may generally comprise exposing the substrate to two or more process gases separately. In time-domain ALD embodiments, exposure to each of the process gases are separated by a time delay/pause to allow the components of the process gases to adhere and/or react on the substrate surface. Alternatively, or in combination, in some embodiments, a purge may be performed before and/or after the exposure of the substrate to the process gases, wherein an inert gas is used to perform the purge. For example, a first process gas may be provided to the process chamber followed by a purge with an inert gas. Next, a second process gas may be provided to the process chamber followed by a purge with an inert gas. In some embodiments, the inert gas may be continuously provided to the process chamber and the first process gas may be dosed or pulsed into the process chamber followed by a dose or pulse of the second process gas into the process chamber. In such embodiments, a delay or pause may occur between the dose of the first process gas and the second process gas, allowing the continuous flow of inert gas to purge the process chamber between doses of the process gases.
In spatial ALD embodiments, exposure to each of the process gases occurs simultaneously to different parts of the substrate so that one part of the substrate is exposed to the first reactive gas while a different part of the substrate is exposed to the second reactive gas (if only two reactive gases are used). The substrate is moved relative to the gas delivery system so that each point on the substrate is sequentially exposed to both the first and second reactive gases. In any embodiment of a time-domain ALD or spatial ALD process, the sequence may be repeated until a predetermined layer thickness is formed on the substrate surface.
A “pulse” or “dose” as used herein is intended to refer to a quantity of a source gas that is intermittently or non-continuously introduced into the process chamber. The quantity of a particular compound within each pulse may vary over time, depending on the duration of the pulse. A particular process gas may include a single compound or a mixture/combination of two or more compounds, for example, the process gases described below.
The durations for each pulse/dose are variable and may be adjusted to accommodate, for example, the volume capacity of the processing chamber as well as the capabilities of a vacuum system coupled thereto. Additionally, the dose time of a process gas may vary according to the flow rate of the process gas, the temperature of the process gas, the type of control valve, the type of process chamber employed, as well as the ability of the components of the process gas to adsorb onto the substrate surface. Dose times may also vary based upon the type of layer being formed and the geometry of the device being formed. A dose time should be long enough to provide a volume of compound sufficient to adsorb/chemisorb onto substantially the entire surface of the substrate and form a layer of a process gas component thereon.
The process of forming the metal film at 704 may begin by exposing the substrate to a first reactive gas. The first reactive gas comprises an alkyl halide and is exposed to the substrate for a first period of time, as shown at 706.
The alkyl halide may be any suitable reactant to adsorb a layer of halogen on the substrate for later reaction. In some embodiments, the alkyl halide comprises carbon and halogen. In some embodiments, the halogen comprises bromine or iodine. In some embodiments, the halogen is insoluble in the metal film. As used in this regard, a halogen which is insoluble in a metal film comprises less than or equal to about 2%, less than or equal to about 1%, or less than or equal to about 0.5% of the metal film on an atomic basis. In some embodiments, the alkyl halide has the general formula R-X, where R is an alkyl, alkenyl, aryl, or other carbonaceous group. In some embodiments, R comprises one to two, one to four, or one to six carbon atoms. In some embodiments, the alkyl halide comprises or consists essentially of iodoethane (H₅C₂I) or diiodomethane (CH₂I₂). As used in this regard, an alkyl halide which consists essentially of a stated species comprises greater than 95%, 98%, 99% or 99.5% of the stated species on a molar basis, excluding any inert diluent gases.
The alkyl halide is delivered to the processing chamber as an alkyl halide containing gas. The alkyl halide containing gas may be provided in one or more pulses or continuously. The flow rate of the alkyl halide containing gas can be any suitable flow rate including, but not limited to, flow rates is in the range of about 1 to about 5000 sccm, or in the range of about 2 to about 4000 sccm, or in the range of about 3 to about 3000 sccm or in the range of about 5 to about 2000 sccm. The alkyl halide containing gas can be provided at any suitable pressure including, but not limited to, a pressure in the range of about 5 mTorr to about 25 Torr, or in the range of about 100 mTorr to about 20 Torr, or in the range of about 5 Torr to about 20 Torr, or in the range of about 50 mTorr to about 2000 mTorr, or in the range of about 100 mTorr to about 1000 mTorr, or in the range of about 200 mTorr to about 500 mTorr.
The period of time that the substrate is exposed to the alkyl halide containing gas may be any suitable amount of time necessary to allow the alkyl halide to form an adequate adsorption layer atop the substrate surface(s). For example, the process gas may be flowed into the process chamber for a period of about 0.1 seconds to about 90 seconds. In some time-domain ALD processes, the alkyl halide containing gas is exposed the substrate surface for a time in the range of about 0.1 sec to about 90 sec, or in the range of about 0.5 sec to about 60 sec, or in the range of about 1 sec to about 30 sec, or in the range of about 2 sec to about 25 sec, or in the range of about 3 sec to about 20 sec, or in the range of about 4 sec to about 15 sec, or in the range of about 5 sec to about 10 sec.
In some embodiments, an inert gas may additionally be provided to the process chamber at the same time as the alkyl halide containing gas. The inert gas may be mixed with the alkyl halide containing gas (e.g., as a diluent gas) or be provided separately and can be pulsed or of a constant flow. In some embodiments, the inert gas is flowed into the processing chamber at a constant flow in the range of about 1 to about 10000 sccm. The inert gas may be any inert gas, for example, such as argon, helium, neon, or combinations thereof.
The temperature of the substrate during deposition can be controlled, for example, by setting the temperature of the substrate support or susceptor. In some embodiments the substrate is held at a temperature in the range of about 0° C. to about 600° C., or in the range of about 25° C. to about 500° C., or in the range of about 50° C. to about 450° C., or in the range of about 100° C. to about 400° C., or in the range of about 200° C. to about 400° C., or in the range of about 250° C. to about 350° C. In some embodiments, the substrate is maintained at a temperature below the decomposition temperature of the metal precursor. In some embodiments, the substrate is maintained at a temperature below the decomposition temperature of the alkyl halide. In some embodiments, the substrate is maintained at a temperature between the decomposition temperature of the alkyl halide and the decomposition temperature of the metal precursor.
In one or more embodiments, the substrate is maintained at a temperature less than or equal to about 400° C., or less than or equal to about 350° C., or less than about 300° C. In one or more embodiments, the substrate is maintained at a temperature greater than or equal to about 250° C., or greater than or equal to about 300° C., or greater than about 350° C. In some embodiments, the substrate is maintained at a temperature of about 280° C.
In addition to the foregoing, additional process parameters may be regulated while exposing the substrate to the alkyl halide containing gas. For example, in some embodiments, the process chamber may be maintained at a pressure of about 0.2 to about 100 Torr, or in the range of about 0.3 to about 90 Torr, or in the range of about 0.5 to about 80 Torr, or in the range of about 1 to about 50 Torr.
Next, at 708, the process chamber (especially in time-domain ALD) may be purged using an inert gas. (This may not be needed in spatial ALD processes as there are gas curtains separating the reactive gases.) The inert gas may be any inert gas, for example, such as argon, helium, neon, or the like. In some embodiments, the inert gas may be the same, or alternatively, may be different from the inert gas provided to the process chamber during the exposure of the substrate to the alkyl halide containing gas at 706. In embodiments where the inert gas is the same, the purge may be performed by diverting the first process gas from the process chamber, allowing the inert gas to flow through the process chamber, purging the process chamber of any excess first process gas components or reaction byproducts. In some embodiments, the inert gas may be provided at the same flow rate used in conjunction with the first process gas, described above, or in some embodiments, the flow rate may be increased or decreased. For example, in some embodiments, the inert gas may be provided to the process chamber at a flow rate of about 0 to about 10000 sccm to purge the process chamber. In spatial ALD, purge gas curtains are maintained between the flows of reactive gases and purging the process chamber may not be necessary. In some embodiments of a spatial ALD process, the process chamber or region of the process chamber may be purged with an inert gas.
The flow of inert gas may facilitate removing any excess first process gas components and/or excess reaction byproducts from the process chamber to prevent unwanted gas phase reactions of the first and second process gases.
Next, at 710, the substrate is exposed to a second process gas for a second period of time. The second process gas comprises a metal precursor which reacts with the adsorbed layer of halogen on the substrate surface to deposit a metal film. The second reactive gas may also be referred to as the metal precursor gas.
The metal precursor may be any suitable precursor to react with the adsorbed halogen layer on the substrate. In some embodiments, the metal precursor comprises a metal center and one or more ligands. In some embodiments, the metal center comprises one or more metal atoms. Stated differently, in some embodiments, the metal precursor is one or more of a dimer, trimer or tetramer.
The metal precursor can be any suitable precursor with a decomposition temperature above the deposition temperature. In some embodiments, the metal precursor comprises substantially no oxygen or nitrogen atoms. Accordingly, in these embodiments, the metal precursor comprises no carbonyl, oxo, amine, or imine ligands. Within these parameters, the number of ligands and types of ligands on the metal precursor can vary, based on, for example, the oxidation state of the metal atom. The metal precursor can be homoleptic or heteroleptic. In some embodiments, the metal precursor comprises at least one ligand comprising an optionally alkyl substituted cyclopentadiene (Cp) ring. In some embodiments, the metal precursor comprises at least one ligand comprising an optionally alkyl substituted benzene ring. In some embodiments, the metal precursor comprises at least one p-cymene ligand. In some embodiments, the metal precursor comprises at least one ligand comprising an open or closed diene. In some embodiments, the metal precursor comprises at least one 1,3-butadiene ligand. In some embodiments, the metal precursor comprises at least one 1,5-hexadiene ligand. In some embodiments, the metal precursor comprises at least one aromatic ligand. In some embodiments, the at least one aromatic ligand comprises a benzene ring. In some embodiments, the benzene ring comprises at least one organic substituent comprising in the range of 1 to 6 carbon atoms. In some embodiments, the aromatic ligand comprises at least one ethylbenzene ligand. In some embodiments, the metal precursor comprises or consists essentially of bis(ethylbenzene)molybdenum. In some embodiments, the metal precursor comprises or consists essentially of p-cymene ruthenium 1,5-hexadiene.
The metal of the metal precursor corresponds to the metal of the deposited metal film. In some embodiments, the metal is selected from molybdenum, ruthenium, cobalt, copper, platinum, nickel or tungsten. In some embodiments, the metal of the metal precursor has an oxidation state of 0. Stated differently, in some embodiments, the metal precursor comprises a zero-valent metal complex.
Additional process parameters may be regulated while exposing the substrate to the metal precursor gas. For example, in some embodiments, the process chamber may be maintained at a pressure of about 0.2 to about 100 Torr, or in the range of about 0.3 to about 90 Torr, or in the range of about 0.5 to about 80 Torr, or in the range of about 1 to about 50 Torr.
The metal precursor is delivered to the processing chamber as a metal precursor gas. The metal precursor gas may be provided in one or more pulses or continuously. The flow rate of the metal precursor gas can be any suitable flow rate including, but not limited to, flow rates is in the range of about 1 to about 5000 sccm, or in the range of about 2 to about 4000 sccm, or in the range of about 3 to about 3000 sccm or in the range of about 5 to about 2000 sccm. The metal precursor gas can be provided at any suitable pressure including, but not limited to, a pressure in the range of about 5 mTorr to about 25 Torr, or in the range of about 100 mTorr to about 20 Torr, or in the range of about 5 Torr to about 20 Torr, or in the range of about 50 mTorr to about 2000 mTorr, or in the range of about 100 mTorr to about 1000 mTorr, or in the range of about 200 mTorr to about 500 mTorr.
The period of time that the substrate is exposed to the metal precursor gas may be any suitable amount of time necessary to allow the metal precursor to react with the adsorbed halogen on the substrate surface. For example, the process gas may be flowed into the process chamber for a period of about 0.1 seconds to about 90 seconds. In some time-domain ALD processes, the metal precursor gas is exposed the substrate surface for a time in the range of about 0.1 sec to about 90 sec, or in the range of about 0.5 sec to about 60 sec, or in the range of about 1 sec to about 30 sec, or in the range of about 2 sec to about 25 sec, or in the range of about 3 sec to about 20 sec, or in the range of about 4 sec to about 15 sec, or in the range of about 5 sec to about 10 sec.
In some embodiments, an inert gas may additionally be provided to the process chamber at the same time as the metal precursor gas. The inert gas may be mixed with the metal precursor gas (e.g., as a diluent gas) or be provided separately and can be pulsed or of a constant flow. In some embodiments, the inert gas is flowed into the processing chamber at a constant flow in the range of about 1 to about 10000 sccm. The inert gas may be any inert gas, for example, such as argon, helium, neon, or combinations thereof.
Next, at 712, the process chamber may be purged using an inert gas. The inert gas may be any inert gas, for example, such as argon, helium, neon, or the like. In some embodiments, the inert gas may be the same, or alternatively, may be different from the inert gas provided to the process chamber during previous process routines. In embodiments where the inert gas is the same, the purge may be performed by diverting the second process gas from the process chamber, allowing the inert gas to flow through the process chamber, purging the process chamber of any excess second process gas components or reaction byproducts. In some embodiments, the inert gas may be provided at the same flow rate used in conjunction with the second process gas, described above, or in some embodiments, the flow rate may be increased or decreased. For example, in some embodiments, the inert gas may be provided to the process chamber at a flow rate of greater than 0 to about 10,000 sccm to purge the process chamber.
While the generic embodiment of the processing method shown in FIG. 7 includes only two pulses of reactive gases, it will be understood that this is merely exemplary and that additional pulses of reactive gases may be used. In some embodiments, the method is performed without the use of an oxygen-containing reactive gas. The sub processes of 704 comprise a cycle. A cycle may be performed in any order as long as the reactive gases are separated by a purge of the processing chamber. In some embodiments, the metal film is deposited at rate greater than or equal to about 0.2 Å/cycle, greater than or equal to about 0.3 Å/cycle, greater than or equal to about 0.4 Å/cycle, greater than or equal to about 0.5 Å/cycle, greater than or equal to about 0.6 Å/cycle, greater than or equal to about 0.7 Å/cycle, greater than or equal to about 0.8 Å/cycle, greater than or equal to about 0.9 Å/cycle, greater than or equal to about 1.0 Å/cycle, or greater than or equal to about 1.2 Å/cycle.
The deposition process is performed as a thermal process without the use of plasma reactants. Stated differently, in some embodiments, the method is performed without plasma.
Next, at 714, it is determined whether the metal film has achieved a predetermined thickness. If the predetermined thickness has not been achieved, the method 700 returns to 704 to continue forming the metal film until the predetermined thickness is reached. Once the predetermined thickness has been reached, the method 700 can either end or proceed to 716 for optional further processing (e.g., bulk deposition of another metal film). In some embodiments, the metal film may be deposited to form a total layer thickness of about 10 Å to about 10,000 Å, or in some embodiments, about 10 Å to about 1000 Å, or in some embodiments, about 50 Å to about 5,000 Å.
In some embodiments, the metal layer comprises greater than or equal to about 75 atomic % molybdenum, or greater than or equal to about 80 atomic % molybdenum, or greater than or equal to about 85 atomic % molybdenum, or greater than or equal to about 90 atomic % molybdenum, or greater than or equal to about 95 atomic % molybdenum.
In some embodiments, the metal layer comprises less than or equal to about 10 atomic % oxygen, or less than or equal to about 9 atomic % oxygen, or less than or equal to about 8 atomic % oxygen, or less than or equal to about 7 atomic % oxygen, or less than or equal to about 6 atomic % oxygen, or less than or equal to about 5 atomic % oxygen, or less than or equal to about 4 atomic % oxygen, or less than or equal to about 3 atomic % oxygen.
In some embodiments, the metal layer comprises in the range of about 0.02 to about 5 atomic % iodine, or less than or equal to about 1 atomic % iodine.
In some embodiments, the metal layer comprises less than or equal to about 20 atomic % carbon, or less than or equal to about 15 atomic % carbon, or less than or equal to about 10 atomic % carbon, or less than or equal to about 5 atomic % carbon.
In some embodiments, the metal layer comprises greater than or equal to about 90 atomic % molybdenum, less than or equal to about 3 atomic % oxygen, less than or equal to about 1 atomic % iodine and less than or equal to about 10 atomic % carbon.
In some embodiments, the metal layer has a resistivity of less than or equal to about 40 μohm-cm, or less than or equal to about 35 μohm-cm, or less than or equal to about 30 μohm-cm, or less than or equal to about 25 μohm-cm, or less than or equal to about 20 μohm-cm. In some embodiments, the metal layer comprises molybdenum and has a resistivity of less than or equal to about 40 μohm-cm, or less than or equal to about 35 μohm-cm, or less than or equal to about 30 μohm-cm, or less than or equal to about 25 μohm-cm, or less than or equal to about 20 μohm-cm.
In some embodiments, the metal film is further processed by annealing the metal film. Without being bound by theory, it is believed that annealing the film at a high temperature under an Ar or H₂atmosphere reduces carbon and halogen impurities in the metal film. In some embodiments, the metal film is annealed under an atmosphere comprising argon or hydrogen gas (H₂) to reduce the atomic concentration of carbon and/or halogen impurities.
The metal film deposited by some embodiments is smoother than the films deposited by known oxygen-based deposition processes. In some embodiments, the metal film has a surface roughness of less than or equal to about 10%, less than or equal to about 8%, less than or equal to about 5%, or less than or equal to about 2%, of a thickness of the metal film.
The purity of the metal film is high. In some embodiments, the metal film has a carbon content less than or equal to about 2%, less than or equal to about 1%, or less than or equal to about 0.5% carbon on an atomic basis. In some embodiments, the metal film has a halogen content less than or equal to about 1% or less than or equal to about 0.5% halogen on an atomic basis. In some embodiments, the metal film has a purity of greater than or equal to about 95%, greater than or equal to about 97%, greater than or equal to about 99%, greater than or equal to about 99.5%, or greater than or equal to about 99.9% metal atoms on an atomic basis.
Some embodiments of the disclosure selectively deposit a first metal film on a second metal surface over a first dielectric surface. These methods are similar to method 700 as described above, except that the substrate provided comprises a first dielectric surface and a second metal surface. The first metal (of the metal film) and the second metal (of the substrate surface) may be the same metal or may be different metals. In some embodiments, the first metal is molybdenum, ruthenium, cobalt, copper, platinum, nickel or tungsten while the second metal is tungsten, cobalt or copper.
The first dielectric surface may be formed from any suitable dielectric material. In some embodiments, the dielectric material comprises nitrogen or oxygen atoms. Without being bound by theory, it is believed that these materials react with the alkyl halide and prevent the halogen from adsorbing onto the substrate surface so as to catalyze the reaction with the metal precursor. Accordingly, little, if any, metal film is formed on the dielectric surface.
In some embodiments, the deposition temperature is below the decomposition temperature of the alkyl halide. Again, without being bound by theory, it is believed that if the alkyl halide decomposes, the halogen will be available for reaction with the metal precursor on all surfaces (regardless of composition), leading to metal film deposition on all substrate surfaces, including the dielectric surface. In some embodiments, the deposition temperature is at or above the decomposition temperature of the alkyl halide.
Some embodiments of the disclosure selectively deposit a first metal film on a first dielectric surface over a second metal surface. These methods are similar to method 700 as described above, except that the substrate provided comprises a first dielectric surface and a second metal surface and the substrate is exposed to a blocking compound at 703.
At 703, a substrate comprising at least a second metal surface and a first dielectric surface is exposed to a blocking compound. The blocking compound may be any suitable compound for blocking deposition on the second metal surface. In some embodiments, the blocking compound comprises at least one triple bond between two carbon atoms. Stated differently, in some embodiments, the blocking compound comprises an alkyne. In some embodiments, the blocking compound has the general formula of R′≡R″. In some embodiments, R′ and R″ are identical. In some embodiments, R′ and/or R″ are an alkyl or other carbonaceous group. In some embodiments, the blocking compound comprises 4-12 carbon atoms. In some embodiments, R′ and/or R″ are linear. In some embodiments, R′ and/or R″ are branched. In some embodiments, the blocking compound comprises 3-hexyne.
The first metal (of the metal film) and the second metal (of the substrate surface) may be the same metal or may be different metals. In some embodiments, the first metal is molybdenum, ruthenium, cobalt, copper, platinum, nickel or tungsten while the second metal is tungsten, cobalt or copper.
The first dielectric surface may be formed from any suitable dielectric material. In some embodiments, the dielectric material comprises nitrogen or oxygen atoms.
As mentioned previously, in some embodiments, the deposition temperature is at or above the decomposition temperature of the alkyl halide. In some embodiments, the deposition temperature is greater than or equal to about 250° C., greater than or equal to about 260° C., greater than or equal to about 270° C., greater than or equal to about 280° C., greater than or equal to about 290° C., or greater than or equal to about 300° C. In some embodiments, the deposition temperature is in the range of about 250° C. to about 450° C., or in the range of about 300° C. to about 400° C. In some embodiments, the deposition temperature is about 350° C.
As stated previously, without being bound by theory, it is believed that these materials react with the alkyl halide and prevent the halogen from adsorbing onto the substrate surface so as to catalyze the reaction with the metal precursor. Accordingly, little, if any, metal film is formed on the dielectric surface.
However, when the deposition temperature is above the decomposition temperature of the alkyl halide, the halogen atoms are deposited on the entire substrate surface, thereby allowing deposition on the dielectric surface. In some embodiments, the metal surface is blocked by the blocking compound, so as to allow little, if any, metal film to be formed on the metal surface. Accordingly, deposition of the metal film is selective to the dielectric surface over the metal surface,
In general terms, the deposition of highly pure metal films can be understood as follows. A substrate, maintained at a deposition temperature, is exposed to an alkyl halide (R-X) to adsorb R and X on the substrate, where R is a carbonaceous group and X is a halogen. R is desorbed in the form of R-R or R⁻, leaving X adsorbed on the substrate. The substrate is exposed to a metal precursor, M-L, where M is the metal and L is a ligand. M-L reacts with the adsorbed X to form M-X on the substrate surface, liberating L. M-X reacts with other M-X moieties on the substrate to form M-M. This reaction may produce either X-X or X. X-X may be desorbed and purged. X⁻ may remain on the surface to further react with M-L.
According to the inventors, this general mechanism relies on several premises. First, X is not soluble in M. Without being bound by theory, the insolubility of X confers that X will not be found in appreciable quantity within the final metal film. While it is possible to ignore this premise (e.g., utilize a halogen soluble in M), using a halogen (X) which is soluble in M is believed to provide metal films with lower purity. Second, in terms of bond strength, M-L is weaker than M-X which is weaker than M-M. Again, without being bound by theory, these thermodynamic relationships ensure that the reactions identified above are thermodynamically favorable. Finally, M-L is thermally stable at the deposition temperature. Stated differently, the thermal decomposition temperature of the metal precursor is higher than the deposition temperature. The theory here states that if the metal precursor decomposes, the deposited film will contain an appreciable quantity of the precursor ligand L, typically seen as carbon impurities.
The inventors have surprisingly found that processes including metal precursors, alkyl halides and process conditions which meet all of the above requirements deposit highly pure metal films.
Additionally, the inventors have surprisingly found that if the deposition temperature is below the thermal decomposition temperature of the alkyl halide, the deposition process is selective to metal surfaces over dielectric surfaces without requiring the use of a blocking layer.
Further, the inventors have surprisingly found that if the deposition temperature is at or above the thermal decomposition temperature of the alkyl halide, the deposition process can be made selective by exposing the metal surface to a small alkyne blocking compound.
Some embodiments of the disclosure advantageously provide methods of depositing conformal metal films on substrates comprising high aspect ratio structures. As used in this regard, the term “conformal” means that the thickness of the metal film is uniform across the substrate surface. As used in this specification and the appended claims, the term “substantially conformal” means that the thickness of the metal film does not vary by more than about 10%, 5%, 2%, 1%, or 0.5% relative to the average thickness of the film. Stated differently a film which is substantially conformal has a conformality of greater than about 90%, 95%, 98%, 99% or 99.5%.
One or more embodiments of the disclosure are directed to memory devices comprising a molybdenum conductive layer. In some embodiments, the molybdenum conductive layer comprises greater than or equal to about 90 at. % molybdenum, less than or equal to about 3 at. % oxygen, less than or equal to about 1 at. % iodine and less than or equal to about 10 at. % carbon, and a resistivity less than or equal to about 40 μohm-cm.
In some embodiments, the molybdenum conductive layer is formed on a barrier layer. The barrier layer of some embodiments has a thickness less than or equal to about 10 Å, 20 Å, 30 Å, 40 Å or 50 Å. In some embodiments, the molybdenum conductive layer is formed on a substrate without an intervening barrier layer.
The above disclosure relates to the deposition of metal films by a sequential pulse of reactants. The following disclosure relates to the deposition of metal films by a simultaneous or constant-flow process. In some embodiments, the sequential pulse methods are ALD methods. In some embodiments, the simultaneous or constant-flow methods are CVD methods. While the process steps differ, many of the reactants and process parameters are similar.
FIG. 8 depicts a generalized method 800 for forming a metal film on a substrate in accordance with one or more embodiment of the disclosure. FIG. 9 depicts an exemplary substrate for processing in accordance with one or more embodiment of the disclosure. The method 800 generally begins at 810, where a substrate 900 upon which a metal film is to be formed is provided and placed into a processing chamber.
Referring to FIG. 9, an exemplary substrate 900 is shown. In some embodiments, the substrate 900 has a substrate surface 905 with at least one feature 910 therein. The feature 910 has a sidewall 912, 914 and a bottom 916. In some embodiments, a dielectric material 920 forms the sidewall 912, 914 and a metallic material 930 forms the bottom 16. The skilled artisan will recognize that the illustrated embodiment refers to two sidewalls, as in a trench-like structure, but that the disclosure is not limited to trenches. In some embodiments, the feature comprises a round via with, technically, has a single round sidewall that would appear as two sidewalls in a cross-sectional view, as shown.
In some embodiments, the substrate 900 may undergo one or more optional pre-processing steps. At 815, the substrate may optionally have one or more layers formed on the substrate surface.
In some embodiments, a metal nitride liner is deposited in the feature 910. In some embodiments, the metal nitride liner comprises titanium nitride. In some embodiments, the metal nitride liner has a thickness in a range of about 15 Å to about 40 Å. In some embodiments, the metal nitride liner has a thickness of about 20 Å or about 30 Å. In some embodiments, there is no liner formed in the feature prior metal film formation. In some embodiments, there is no liner between the metal film and the bottom of the feature.
In some embodiments, a seed layer is deposited on the substrate surface. In some embodiments, the seed layer is a conformal layer. In some embodiments, the seed layer is continuous. In some embodiments, the thickness of the seed layer is in a range of about 1 nm to about 5 nm, or in a range of about 1 nm to about 4 nm. In some embodiments, the seed layer comprises a ruthenium layer deposited by a known atomic layer deposition method. In some embodiments, the seed layer is deposited by an ALD cycle comprising a ruthenium precursor exposure and an alkyl halide exposure with intervening purges. In some embodiments, the seed layer is deposited by an ALD cycle comprising a ruthenium precursor exposure and an ammonia plasma exposure with intervening purges.
In some embodiments, the bottom 916 comprises a metal and the optional pre-process comprises a cleaning process. In some embodiments, the metal bottom 916 of the feature is cleaned to remove oxides from the metal prior to formation of a metal film in the feature.
At 820, the substrate is optionally exposed to a blocking compound. This process step is described more fully below and may be useful for controlling the selectivity of the deposition process on a substrate comprising both a metal surface and a dielectric surface.
At 830, a metal film is formed on the substrate. The metal film of some embodiments is formed by exposing the substrate to a metal precursor and an alkyl halide catalyst while the substrate is maintained at a deposition temperature. In some embodiments, the alkyl halide catalyst and the metal precursor are exposed the substrate at the same time. In some embodiments, the metal precursor and the alkyl halide catalyst are exposed to the substrate separately and sequentially. In embodiments with separate exposures, each “cycle” is a single exposure to the alkyl halide catalyst and the metal precursor, in either order. The process of forming the metal film at 830 may begin by soaking the substrate with a catalytic gas. The catalytic gas comprises an alkyl halide and is exposed to the substrate for a first period of time, as shown at 840. In some embodiments, the catalytic gas comprises an alkyl halide catalyst that forms a catalyst layer on the metal bottom of the feature.
The alkyl halide may be any suitable reactant to adsorb a layer on the substrate for later reaction. Stated differently, soaking the substrate in the alkyl halide forms an activated substrate surface. The alkyl halide is described above and elsewhere herein.
The alkyl halide may be provided to the processing chamber in one or more pulses or continuously. In some embodiments, the alkyl halide is provided with an inert carrier gas and is referred to the alkyl halide containing gas. The flow rate and pressure of the alkyl halide or alkyl halide containing gas can be any suitable values. Exemplary flow rates and pressures disclosed elsewhere herein for the alkyl halide containing gas are also applicable in this embodiment.
The period of time that the substrate is soaked in the alkyl halide may be any suitable amount of time necessary to allow the alkyl halide to form an adequate adsorption layer on the substrate surface(s). For example, the alkyl halide may be allowed to soak the substrate for a period of greater than about 3 seconds or greater than about 5 seconds. In some embodiments, the soak period is in a range of about 3 seconds to about 60 seconds.
In some embodiments, an inert gas may additionally be provided to the process chamber at the same time as the alkyl halide containing gas. The inert gas may be mixed with the alkyl halide (e.g., as a diluent gas) or be provided separately and can be pulsed or of a constant flow. The inert gas may be any inert gas, for example, such as argon, helium, neon, or combinations thereof.
Next, at 850, the substrate is exposed to a second process gas for a second period of time. The second process gas comprises a metal precursor which reacts with the adsorbed layer of alkyl halide or halogen on the substrate surface to deposit a metal film. The second reactive gas may also be referred to as the metal precursor gas.
The metal precursor may be any suitable precursor to react with the adsorbed alkyl halide layer or halogen layer on the substrate. Suitable metal precursors are described elsewhere herein.
The metal precursor is delivered to the processing chamber as a metal precursor gas. The metal precursor gas may be provided in one or more pulses or continuously. The flow rate and pressure of the metal precursor gas can be any suitable flow rate and pressure. Exemplary values for flow rate and pressure are discussed elsewhere herein.
The period of time that the substrate is exposed to the metal precursor gas may be any suitable amount of time necessary to allow the metal precursor to react with the adsorbed halogen on the substrate surface. For example, the process gas may be flowed into the process chamber for a period of greater than or equal to about 60 seconds. In some embodiments, the period of exposure to the metal precursor is about 100 seconds, about 200 seconds, about 300 seconds, about 400 seconds or about 500 seconds.
The temperature of the substrate during exposure to the metal precursor can be controlled, for example, by setting the temperature of the substrate support or susceptor. This temperature is also referred to as the deposition temperature. In some embodiments, the substrate is maintained at a temperature below the decomposition temperature of the metal precursor. In some embodiments, the substrate is maintained at a temperature below the decomposition temperature of the alkyl halide. In some embodiments, the substrate is maintained at a temperature between the decomposition temperature of the alkyl halide and the decomposition temperature of the metal precursor.
In one or more embodiments, the substrate is maintained at a temperature less than or equal to about 400° C., or less than or equal to about 350° C., or less than or equal to about 300° C., or less than or equal to about 250° C., or less than or equal to about 200° C. In one or more embodiments, the substrate is maintained at a temperature greater than or equal to about 150° C., or greater than or equal to about 200° C., or greater than or equal to about 250° C., or greater than or equal to about 300° C., or greater than or equal to about 350° C. In some embodiments, the substrate is maintained at a temperature of about 225° C. or about 280° C.
The deposition process is performed as a thermal process without the use of plasma reactants. Stated differently, the method is performed without plasma.
Next, at 860, it is determined whether the metal film has achieved a predetermined thickness. If the predetermined thickness has not been achieved, the method 800 returns to 850 to continue exposing the substrate to the metal precursor until the predetermined thickness is reached. Once the predetermined thickness has been reached, the method 800 can either end or proceed to 870 for optional further processing. In some embodiments, the metal film may be deposited to form a total layer thickness of about 10 Å to about 10,000 Å, or in some embodiments, about 20 Å to about 1000 Å, or in some embodiments, about 50 Å to about 200 Å.
Some embodiments of the disclosure selectively deposit a metal film on a metal surface over a first dielectric surface. These methods are similar to method 800 as described above. The substrate provided comprises a dielectric surface and a metal surface. In some embodiments, a substrate as shown in FIG. 9 is processed to selectively form bottom up gap fill on the metal surface at the bottom 916 of the feature 910.
The metal of the metal film and the metal of the substrate surface may be the same metal or may be different metals. The dielectric surface may be formed from any suitable dielectric material. In some embodiments, the dielectric material comprises nitrogen or oxygen atoms. Without being bound by theory, it is believed that these materials react with the alkyl halide and prevent the halogen from adsorbing onto the substrate surface so as to catalyze the reaction with the metal precursor. Accordingly, little, if any, metal film is formed on the dielectric surface.
In some embodiments, the deposition temperature is below the decomposition temperature of the alkyl halide. Again, without being bound by theory, it is believed that if the alkyl halide decomposes, the halogen will be available for reaction with the metal precursor on all surfaces (regardless of composition), leading to metal film deposition on all substrate surfaces, including the dielectric surface. In some embodiments, the deposition temperature is at or above the decomposition temperature of the alkyl halide.
Some embodiments of this disclosure advantageously provide methods for controlling the deposition of a metal film. In some embodiments, the rate of deposition is controlled. In some embodiments, the location of deposition is controlled.
The methods of various embodiments use methods of atomic layer deposition (ALD) or chemical vapor deposition (CVD) to form the metal films. The above disclosure describes an exemplary ALD process with respect to FIG. 7 and an exemplary CVD process with respect to FIG. 8.
As stated previously, the generalized deposition processes shown in FIGS. 7 and 8 are performed as thermal processes without the use of plasma reactants. The use and effect of plasmas and other additional reactants is discussed further below.
Some embodiments of the disclosure advantageously provide methods of depositing metal films within substrate features or other structures. Exemplary features or structures include, but are not limited to, trenches and vias.
Some embodiments of the disclosure advantageously provide deposition control methods for reducing film deposition outside of a target feature and near the feature opening. Without being bound by theory, it is believed that reducing deposition in these areas allows faster gapfill within the target feature and reduces clogging near the feature opening and formation of voids or seams within the feature.
Referring to FIGS. 7 and 8, without limiting the scope of the above disclosure, both the ALD and CVD processes described above utilize an alkyl halide and a metal precursor to deposit a metal film. Without being bound by theory, it is believed that the alkyl halide functions as a catalyst in the deposition of the metal film. Accordingly, as particularly evidenced by the CVD process, a single exposure of the substrate surface to an alkyl halide can be used to deposit a thickness of more than 10 nm of metal film.
Some embodiments of the disclosure advantageously provide deposition control methods for reducing the activity of the catalyst in predetermined areas of the substrate surface. In some embodiments, the activity of catalyst is reduced. In some embodiments, the activity of the catalyst is eliminated.
Referring to FIGS. 10A-10D, an exemplary substrate 400 is shown during processing according to one or more embodiments of this disclosure. The substrate 1000 illustrated in FIGS. 10A-10D is simplified for explanation. As mentioned above, and shown in FIG. 9, in some embodiments, the substrates of this disclosure contain features or structures not depicted in FIGS. 10A-10D.
In FIG. 10A, the substrate 1000 contains a substrate surface 1010. In FIG. 4B, the substrate surface 1010 is exposed to an alkyl halide to form an activated surface 1020. As described above, the alkyl halide 1040 adsorbs to the substrate surface 1010 to form an activated substrate surface 1020.
In FIG. 10C, a predetermined area of the activated surface 1020 is exposed to a deactivation treatment to form a deactivated surface 1030. The alkyl halide 1040 shown in FIGS. 10B and 10C is shown as circular or ovoid, however no specific molecular shape is intended to be conveyed. Similarly, the difference between the circular shapes shown in FIGS. 10B and 10C and the ovoid shapes shown in FIG. 10C is meant only to convey the activity and/or relative concentration of alkyl halide on the substrate surfaces.
In FIG. 10D, the substrate 1000 is exposed to a metal precursor to form a metal film 1050. As shown in FIG. 10D, the thickness T₁of the metal film 1050 on the activated surface 1020 is greater than the thickness T₂of the metal film 1050 on the deactivated surface 1030.
In some embodiments, the deactivation treatment reduces the concentration of the alkyl halide on the activated surface 1020. In some embodiments, the deactivation treatment reduces the catalytic activity of the alkyl halide on the activated surface 1020.
In some embodiments, the method described above with respect to FIGS. 10A-10D is modified to include the deactivation treatment before exposure to the alkyl halide. In this regard, the deactivation treatment may be understood to “superactivate” a predetermined area of the substrate surface 1010 before exposure to the alkyl halide. Upon exposure to the alkyl halide, the “superactivated” surface forms a higher concentration or activity of alkyl halide than a surface not exposed to the deactivation treatment. The difference in concentration and/or activity between the surfaces may be used to control deposition. In some embodiments, the surfaces may be further deactivated as described above with respect to FIGS. 10C-10D.
The thickness T₁is greater than the thickness T₂. Accordingly, some embodiments of the disclosure advantageously provide deposition control methods for controlling the amount of deposition in predetermined areas of the substrate surface.
In some embodiments, the ratio of T₁:T₂is greater than or equal to about 1:1, greater than or equal to about 2:1, greater than or equal to about 3:1, greater than or equal to about 4:1, greater than or equal to about 5:1, or greater than or equal to about 10:1. In some embodiments, little to no deposition of metal occurs on the deactivated surface 1030. Stated differently, in some embodiments, thickness T₂is about 0. Stated differently, the amount of metal film 1050 deposited on the deactivated surface 1030 is essentially none. As used in this regard, “essentially none” means that the metal film on the deactivated surface covers less than 5%, less than 2%, less than 1% or less than 0.5% of the deactivated surface.
The thicknesses of the metal film 1050 deposited on the activated surface 1020 and the deactivated surface 1030 is directly proportional to the rates of deposition on the activated surface 1020 and the deactivated surface 1030. Accordingly, some embodiments of the disclosure advantageously provide deposition control methods for controlling the rate of deposition in predetermined areas of the substrate surface.
In some embodiments, the entire substrate surface is exposed to the deactivation treatment. Some embodiments of the disclosure may be used to control the amount of deposition on the entire substrate. Some embodiments of the disclosure may be used to control the rate of deposition on the entire substrate.
In some embodiments, not shown, the substrate 1000 comprises one or more features. In some embodiments, the deactivated surface 1030 is the surface outside of the one or more feature. In some embodiments, the deactivated surface 1030 is the surface near the top of the sidewall of the one or more feature.
Without being bound by theory, it is believed that the surface near substrate features and the top surfaces of the sidewalls of those features are more highly activated (exhibits greater deposition) due to multiple exposed faces within close proximity. The greater deposition on these surfaces increases the likelihood that the feature will close before a sufficient amount of film is formed inside of the feature. When features close a seam or void is often formed. Accordingly, in some embodiments, the deactivated surface 1030 is the surface near the top of the one or more feature. Further, in some embodiments, the deactivated surface 1030 is the surface near the substrate feature. In some embodiments, the metal film deposited within the feature has reduced seams or voids. In some embodiments, the metal film deposited within the feature has substantially no seam or voids. As used in this regard, the term “substantially no seam” means that any gap formed in the film between the sidewalls is less than about 1% of the cross-sectional area of the sidewall.
In some embodiments, the predetermined areas of the substrate are exposed to hydrogen gas without the use of plasma.
In some embodiments, a hydrogen gas pulse is introduced into the ALD deposition cycle described above. Stated differently, a substrate may be exposed to a pulse sequence of alkyl halide, purge, hydrogen gas, purge, metal precursor, purge. In some embodiments, the substrate is exposed to an additional pulse of hydrogen gas followed by a purge after exposure to the metal precursor. In some embodiments, the substrate is exposed to an additional pulse of hydrogen gas followed by a purge after exposure to the alkyl halide. In some embodiments, the purge phase between each exposure to the metal precursor and/or the alkyl halide is performed in some, but not all cycles.
In some embodiments a hydrogen gas exposure is introduced into the CVD deposition cycle described above. Stated differently, a substrate may be soaked with the alkyl halide, exposed to hydrogen gas and exposed to the metal precursor. In some embodiments, the substrate is exposed to the hydrogen gas before exposure to the metal precursor. In some embodiments, the hydrogen gas and the metal precursor are flowed simultaneously.
In some embodiments, the predetermined areas of the substrate are exposed to a plasma comprising one or more of hydrogen (H₂), ammonia (NH₃) or argon (Ar). In some embodiments, the plasma used to deactivate the surface is a low powered plasma. In some embodiments, the plasma has a power in a range of about 50 W to about 500 W, in a range of about 50 W to about 300 W, in a range of about 50 W to about 200 W, or in a range of about 50 W to about 100 W.
In some embodiments, the plasma exposure time is less than or equal to about 30 seconds, less than or equal to about 20 seconds, less than or equal to about 15 seconds, less than or equal to about 10 seconds, less than or equal to about 5 seconds, or less than or equal to about 2 seconds.
In some embodiments, the plasma is a conductively coupled plasma (CCP). In some embodiments, the plasma is an inductively coupled plasma (ICP). In some embodiments, the plasma is a direct plasma generated within the processing environment. In some embodiments, the plasma is a remote plasma generated outside of the processing environment.
In some embodiments, a plasma pulse is introduced into the ALD deposition cycle described above. In some embodiments, the plasma pulse replaces the hydrogen gas pulse described above with respect to the ALD deposition cycle.
In some embodiments, a plasma pulse is introduced into the CVD deposition cycle described above. In some embodiments, the plasma pulse replaces the hydrogen gas exposure described above with respect to the CVD deposition cycle.
FIG. 11 illustrates a process for seam-free gap fill according to one or more embodiment of the disclosure. The substrate 1100 illustrated has at least one feature 1105 with a first metal 1110 at the bottom 1106 of the feature 1105 and at least one dielectric sidewall 1120. The first metal 1110 has a first metal surface 1111 that is exposed within the feature 1105. The dielectric sidewall 1120 has a top surface 1121 outside of the feature 1105 and one or more sidewall surface 1122 within the feature 1105.
In some embodiments, the substrate 1100 is exposed to an optional cleaning process. The cleaning process cleans the first metal surface 1111 at the bottom 1106 of the feature 1105. In some embodiments, the cleaning process removes oxides from the first metal surface 1111. The cleaning process of some embodiments comprises degassing the substrate with or without hydrogen, an argon sputter with or without hydrogen, water vapor cleaning or APC clean.
In some embodiments, a metal film 1130 is deposited using a catalyst-enhanced chemical vapor deposition (CECVD) process. A metal film 1130 (e.g., a ruthenium film) is selectively deposited on the first metal 1110 to cover the first metal surface 1111. The metal film 1130 is deposited to a thickness that partially fills the feature 1105 so that the top surface of the metal film 1131 is below the top surface 1121 of the dielectric 1120.
A blocking layer 1140 is optionally formed on the top surface 1131 of the metal film 1130. The blocking layer 1140 can be any suitable material known to the skilled artisan that can prevent deposition of a liner material on the top surface 1131 of the metal film 1130. In some embodiments, the blocking layer 1140 comprises a self-assembled monolayer (SAM).
In some embodiments, a conformal liner 1150 is formed on the dielectric sidewall 1122 and the top surface 1121 of the dielectric 1120. In some embodiments there is substantially no conformal liner 1150 formed on the top surface 1131 of the metal film 1130 or on the optional blocking layer 1140. As used in this manner, the term “substantially no” means that less than or equal to about 10%, 5%, 2% or 1% of the surface area of the metal film 1130 or the optional blocking layer 1140 has liner material deposited thereon. This does not include the edges of the sidewalls where the sidewall intersects the top surface of the metal film or the optional blocking layer. In some embodiments, the conformal liner 1130 has a thickness less than or equal to about 30 Å, 25 Å or 20 Å. In some embodiments, the conformal liner 1130 has a thickness sufficient to form a continuous film. In some embodiments, the conformal liner 1130 comprises titanium nitride (TiN) and/or tantalum nitride (TaN).
In some embodiments, the blocking layer 1140 is optionally removed from the top surface 1131 of the metal films 1130. The blocking layer 1140 can be removed by any suitable technique known to the skilled artisan.
In some embodiments, the feature 1105 is filled with the metal film 1130 to 1130 form an overburden 1133 that covers the conformal liner 1150 on the dielectric sidewall and the top surface of the dielectric.
In some embodiments, the metal film 1130 is optionally annealed to change some property of the film and form an annealed metal film 1160. For example, in some embodiments, the metal film 1130 is annealed to increase the density of the film. Annealing can be done by any suitable technique under any suitable conditions known to the skilled artisan.
In some embodiments, a portion of the annealed metal film 1160 (or the metal film 1130 if not annealed) is removed by any suitable technique. In some embodiments, a portion of the annealed metal film 1160 (or metal film 1130) and at least some of the conformal liner 1150 is removed to expose the top surface 1121 of the dielectric 1120. In some embodiments, a portion of the annealed metal film 1160 (or metal film 1130) and a portion of the dielectric 1120, and at least some of the conformal liner 1150 is removed. In some embodiments, all of the conformal liner 1150 is removed. In some embodiments, the annealed metal film 1160 (or metal film 1130), the conformal liner 1150 and the portion of the dielectric 1120 is removed by chemical-mechanical planarization.
In some embodiments, one or more of the blocking layer 1140 or conformal liner 1150 are deposited prior to formation of the metal film 1130, so that the blocking layer 1140 forms directly on the first metal 1110. In some embodiments, the blocking layer 1140 is removed from the first metal 1110 surface prior to depositing the metal film 1130. In some embodiments of this sort, the deposition of the metal film 1130 proceeds with an initial ALD process and then a CECVD process to grow the metal film.
In some embodiments, a combination of atomic layer deposition and catalyst enhanced chemical vapor deposition is used. The ALD portion of some embodiments follows a sequence of metal precursor (e.g., ruthenium precursor) soaking, a purge, catalyst precursor (e.g., iodine precursor) soak, and purge. The individual exposures during the ALD portion, according to some embodiments, have short durations. In some embodiments, the soaking portions are performed for less than 10 seconds, 5 second, 4 seconds, 3 seconds or 2 seconds. In some embodiments, the metal precursor soak is longer than the catalyst precursor soak. In some embodiments, the purging portions are performed for less than 5 second, 4 seconds, 3 seconds, 2 seconds or 1 second. The CECVD portion of a process, whether coupled to an ALD segment or not, typically has longer pulse times and a different pulse sequence. The CECVD sequence of some embodiments comprises a catalyst precursor soak, followed by a metal precursor soak, then a purge. The catalyst precursor soak of some CECVD embodiments has a duration in the range of 5 seconds to 300 seconds, 10 seconds to 240 seconds, 15 seconds to 210 seconds, 20 seconds to 180 seconds, 25 seconds to 120 seconds or 30 seconds to 60 seconds. In some embodiments, the metal precursor soak of some CECVD embodiments has a duration in the range of 20 seconds to 1200 seconds, 30 seconds to 800 seconds, 40 seconds to 600 seconds, 50 seconds to 450 seconds or 60 seconds to 300 seconds. In some embodiments, the catalyst soak has a shorter duration than the metal soak. In some embodiments, the purge has a duration in the range of 1 second to 100 seconds, 2 seconds to 80 seconds, 3 seconds to 60 seconds, 4 seconds to 30 seconds or 5 seconds to 10 seconds.
In some embodiments, the process comprises an initial ALD type process to build a thickness of the second metal. Once a predetermined thickness of the second metal has been formed, the CECVD process is performed repeatedly to grow a film with a predetermined thickness. In some embodiments, the CECVD process is not effective for second metal growth without an initial layer of the metal deposited by a selective ALD process. The ALD type sequence of some embodiments deposits the second metal at a faster rate than the CECVD process. In some embodiments, after forming a metal film 1130 to a predetermined thickness (e.g., to the top of the feature), the process sequence switches to an ALD type sequence. The metal film can then be further processed as described herein.
Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.
Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A metal deposition method comprising sequentially exposing a substrate having at least one feature comprising a bottom and sidewalls to a metal precursor and an alkyl halide catalyst while the substrate is maintained at a deposition temperature to form a metal film on the bottom of the feature, the bottom of the feature comprising a first metal and the sidewalls of the feature comprising a dielectric, the metal precursor having a decomposition temperature above the deposition temperature, and the alkyl halide comprising carbon and halogen, and the halogen comprising bromine or iodine.

2. The method of claim 1, wherein the first metal at the bottom of the feature comprises one or more of molybdenum, ruthenium, cobalt, copper, platinum, nickel or tungsten.

3. The method of claim 1, wherein the metal film comprises one or more of tungsten, ruthenium, molybdenum or copper.

4. The method of claim 1, wherein the metal precursor comprises a metal atom bonded to one or more of an optionally alkyl substituted benzene ring and an open or closed diene.

5. The method of claim 1, wherein the alkyl halide consists essentially of iodoethane or diiodomethane.

6. The method of claim 1, wherein the metal film is formed selectively on the bottom of the feature relative to the sidewalls.

7. The method of claim 1, wherein the metal film fills the feature in a bottom-up manner to form a seam-free gap fill.

8. The method of claim 7, wherein the seam-free gap fill is formed without a liner between the metal film and the sidewalls.

9. The method of claim 1, wherein the metal precursor and the alkyl halide catalyst are exposed to the substrate together.

10. The method of claim 1, wherein the metal precursor and the alkyl halide catalyst are exposed to the substrate separately and sequentially in a cycle.

11. The method of claim 10, wherein the alkyl halide catalyst is exposed to the substrate prior to the metal precursor exposure to form a catalyst layer on the metal bottom of the feature.

12. The method of claim 11, further comprising exposing the substrate with the catalyst layer on the metal bottom of the feature to an anisotropic etch to remove any catalyst from the dielectric.

13. The method of claim 11, wherein the metal film has a growth rate greater than or equal to about 0.8 Å/cycle.

14. The method of claim 1, further comprising cleaning the first metal at the bottom of the feature to remove oxides from the first metal prior to exposure to the metal precursor and alkyl halide catalyst.