US20220025513A1

US20220025513A1 - Selective deposition on metal or metallic surfaces relative to dielectric surfaces

Info

Publication number: US20220025513A1
Application number: US17/450,742
Authority: US
Inventors: Suvi P. Haukka; Raija H. MATERO; Elina Färm; Tom E. Blomberg
Original assignee: ASM IP Holding BV
Current assignee: ASM IP Holding BV
Priority date: 2015-08-03
Filing date: 2021-10-13
Publication date: 2022-01-27
Also published as: US11174550B2; KR20230051455A; US10428421B2; TWI698544B; KR102520620B1; TW202035768A; US20200010953A1; KR20170016310A; TW201712140A; US20170037513A1; TWI721896B

Abstract

Methods are provided for selectively depositing a material on a first metal or metallic surface of a substrate relative to a second, dielectric surface of the substrate, or for selectively depositing metal oxides on a first metal oxide surface of a substrate relative to a second silicon oxide surface. The selectively deposited material can be, for example, a metal, metal oxide, metal nitride, metal silicide, metal carbide and/or dielectric material. In some embodiments a substrate comprising a first metal or metallic surface and a second dielectric surface is alternately and sequentially contacted with a first vapor-phase metal halide reactant and a second reactant. In some embodiments a substrate comprising a first metal oxide surface and a second silicon oxide surface is alternately and sequentially contacted with a first vapor phase metal fluoride or chloride reactant and water.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 16/575,112, filed Sep. 18, 2019, which is a continuation of U.S. application Ser. No. 15/221,453, filed Jul. 27, 2016, now U.S. Pat. No. 10,428,421, which claims priority to U.S. Provisional Application No. 62/200,502, filed Aug. 3, 2015, and U.S. Provisional Application No. 62/281,593, filed Jan. 21, 2016, each of which is hereby incorporated by reference in its entirety.

BACKGROUND

Field

The present application relates to selective deposition of a material on a first metal or metallic surface of a substrate relative to a second dielectric surface, such as an SiO₂surface.

Description of the Related Art

Integrated circuits are currently manufactured by an elaborate process in which various layers of materials are sequentially constructed in a predetermined arrangement on a semiconductor substrate.
The predetermined arrangement of materials on a semiconductor substrate is often accomplished by deposition of a material over the entire substrate surface, followed by removal of the material from predetermined areas of the substrate, such as by deposition of a mask layer and subsequent selective etching process.
In certain cases, the number of steps involved in manufacturing an integrated surface on a substrate may be reduced by utilizing a selective deposition process, wherein a material is selectively deposited on a first surface relative to a second surface without the need, or with reduced need for subsequent processing. Methods are disclosed herein for selective deposition on a first metal or metallic surface of substrate relative to a second, dielectric surface of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The application will be better understood from the Description and from the appended drawings, which are meant to illustrate and not to limit the invention, and wherein:

FIG. 1 is a process flow diagram generally illustrating a process for selectively depositing a material on a first metal surface of a substrate relative to a second dielectric surface of the same substrate.

FIG. 2 is a cross sectional scanning electron micrograph showing approximately 100 nm of NbO_xdeposited on a 20 nm to 30 nm thick layer of tungsten deposited by a physical vapor deposition (PVD) process on approximately a 20 nm thick layer of Ti.

FIG. 3 is a scanning electron micrograph of an Nb₂O₅film which has been selectively deposited on a tungsten/tungsten oxide surface of a substrate relative to the SiO₂surface of the same substrate.

DETAILED DESCRIPTION

According to some aspects of the present disclosure, selective deposition without need for any separate passivation chemicals or blocking agents, can be used to deposit a material on a first surface relative to a second surface. In some embodiments however, passivation chemicals or blocking agents may be used, if desired. These may include, for example, self-assembled monolayers. In some embodiments a material is selectively deposited on a first metal or metallic surface of a substrate relative to a second, dielectric surface of the substrate. In some embodiments the second surface comprises —OH groups, such as a SiO₂based surface. In some embodiments a metal oxide such as NbO_xis selectively deposited on a first metal oxide or dielectric surface of a substrate relative to a second, different SiO₂surface. In some embodiments atomic layer deposition (ALD) type processes are used. After selective deposition of the material is completed, further processing can be carried out to form the desired structures.
Unless otherwise indicated, if a surface is referred to as a metal surface herein, it may be a metal surface or a metallic surface. In some embodiments the metal or metallic surface may comprise metal, for example an elemental metal, metal nitride, metal silicide, metal carbide and/or mixtures thereof. In some embodiments the metal or metallic surface may comprise surface oxidation, for example a surface layer of native metal oxide. In some embodiments the metal or metallic material of the metal or metallic surface is electrically conductive with or without surface oxidation. In some embodiments the metal or metallic surface comprises silicon, such as H-terminated silicon. In some embodiments the metal or metallic surface is a silicon surface such as an H-terminated silicon surface. In some embodiments the metal or metallic surface is not a silicon surface such as a H-terminated silicon surface. The first metal or metallic surface may also be referred to herein as the first surface.
In some embodiments a metal or a metallic surface comprises one or more transition metals. In some embodiments a metal or metallic surface comprises aluminum. In some embodiments the metal or metallic surface comprises one or more of Al, Cu, Co, Ni, W. In some embodiments a metallic surface comprises titanium nitride. In some embodiments the metal or metallic surface comprises one or more noble metals, such as Ru. In some embodiments the metal or metallic surface comprises a conductive metal oxide, such as a noble metal oxide like ruthenium oxide.
In some embodiments a material is selectively deposited on a first metal surface comprising a metal oxide surface. A metal oxide surface may be, for example a tungsten oxide, hafnium oxide, titanium oxide, aluminum oxide, or zirconium oxide surface. In some embodiments a metal oxide surface is an oxidized surface of a metallic material. In some embodiments a metal oxide surface is created by oxidizing at least the surface of a metallic material using oxygen compound, such as compounds comprising O₃, H₂O, H₂O₂, O₂, oxygen atoms, plasma or radicals or mixtures thereof. In some embodiments a metal oxide surface is a native oxide formed on a metallic material.
In some embodiments a material is selectively deposited on a first surface comprising a dielectric surface relative to a second SiO₂surface.
In some embodiments a metal, metal oxide, metal silicide, metal carbide or metal nitride or mixture thereof is selectively deposited on a first metal or metallic surface of a substrate relative to a second dielectric surface of the substrate. In some embodiments the material that is selectively deposited is not tungsten or tungsten silicide. The term dielectric is used herein for the sake of simplicity in distinguishing from the other surface, namely the metal or metallic surface. Unless indicated otherwise with respect to particular embodiments, the term dielectric in the context of this application can be understood to cover all surfaces which are electrically non-conducting or have very high resistivity. In some embodiments the dielectric surface may be referred to herein as the second surface. In some embodiments the second surface may comprise any dielectric surface.
In some embodiments a metal oxide is selectively deposited on a first metal surface of a substrate, wherein the metal surface comprises a metal oxide relative to a second SiO₂surface. In some embodiment the first metal oxide surface may be, for example a tungsten oxide, hafnium oxide, titanium oxide, aluminum oxide, or zirconium oxide surface. In some embodiments the metal oxide is deposited on a first dielectric surface relative to a second SiO₂surface. In some embodiments the metal oxide that is deposited on the first metal oxide surface is NbO_x, for example Nb₂O₅. The second SiO₂surface may be, for example, a native oxide, a thermal oxide or a chemical oxide.
For simplicity, materials, such as films, may be referred to herein by the formula MO_x, where M is a metal. The formula MO_xindicates that the material comprises primarily a metal, M, and oxygen, however impurities may also be present in such a material. In some embodiments the formula MO_xindicates that the material is an oxide of the metal M.
FIG. 1 is a process flow diagram generally illustrating a process 10 for selectively depositing a material on a first metal or metallic surface of a substrate relative to a second dielectric surface of the same substrate.
In some embodiments a substrate is provided comprising a first metal or metallic surface and a second dielectric surface at step 11. In some embodiments a substrate is provided that comprises a first metal surface comprising a metal oxide surface. In some embodiments the second surface may comprise —OH groups. In some embodiments the second surface may be a SiO₂based surface. In some embodiments the second surface may comprise Si—O bonds. In some embodiments the second surface may comprise a SiO₂based low-k material. In some embodiments the second surface may comprise more than about 30%, or more than about 50% of SiO₂. In some embodiments the second surface may comprise GeO₂. In some embodiments the second surface may comprise Ge—O bonds.
In some embodiments a pretreatment or cleaning step 12 is optionally used before contacting the substrate with the first reactant. The pretreatment or cleaning step may comprise a plasma, hydrogen or thermal treatment. For example, in some embodiments an oxidized portion of the metal or metallic surface of the substrate, if any, is optionally reduced. In some embodiments the oxidized surface may be reduced with hydrogen or hydrogen containing plasma, radicals or atoms. In some embodiments the oxidized surface is reduced without plasma, such as by exposure to a carboxylic acid, such as formic acid.
Following the optional pretreatment or cleaning step 12, if conducted, the substrate is contacted with a first reactant that comprises a metal halide at step 13. In some embodiments the metal halide is a metal fluoride or metal chloride. In some embodiments the metal halide is adsorbed selectively on the metal or metallic surface of the substrate relative to the dielectric surface. In some embodiments a greater amount of metal halide adsorbs on the metal or metallic surface relative to the dielectric surface. In some embodiments substantially no metal halide adsorbs on the dielectric surface. In some embodiments no metal halide is adsorbed on the dielectric surface. In some embodiments no substantial or detectable amount of metal halide is adsorbed on the dielectric surface.
In some embodiments a substrate comprising a first metal surface comprising a metal oxide surface and a second SiO₂surface is contacted with a metal halide reactant, such as metal fluoride or metal chloride. For example, the substrate may be contacted with NbF₅. In some embodiments the metal halide is adsorbed selectively on the metal oxide surface relative to the SiO₂surface. In some embodiments a greater amount of metal halide adsorbs on the metal oxide surface relative to the SiO₂surface. In some embodiments substantially no metal halide adsorbs on the SiO₂surface. In some embodiments no metal halide is adsorbed on the SiO₂surface. In some embodiments no substantial or detectable amount of metal halide is adsorbed on the SiO₂surface.
In some embodiments the adsorbed metal halide on the metal, metallic or metal oxide surface can then be reacted with one or more additional reactants to form a desired material, such as an oxide or metallic material, a silicide, metal nitride, metal carbide or mixture thereof at step 14. For example, in some embodiments the adsorbed metal halide can be reacted with a second reactant comprising an —OH group, such as water, thereby forming a metal oxide. Additional reactants can be provided in order to obtain the desired material.
In some embodiments after removing the metal halide reactant from the reaction space or exposing the substrate to purge gas, the substrate is contacted with a second reactant at step 14. In some embodiments the second reactant comprises an —OH group. In some embodiments the second reactant is water.
Contacting the substrate with the first metal halide reactant, removing the first metal halide reactant from the reaction space, contacting the substrate with the second reactant and removing the second reactant from the reaction space together can be considered a deposition cycle. That is, steps 13 and 14 can be considered a deposition cycle. In some embodiments removing the metal halide reactant and/or removing the second reactant may be accomplished with the aid of an inert purge gas. The deposition cycle can be repeated multiple times to selectively deposit the desired amount of material on the metal or metallic surface. For example, in some embodiments a thin film of deposited material of a desired thickness can be formed.
Once the material is deposited to a desired thickness on the first metal surface, it can optionally be treated at step 15 to form a desired material. For example, after deposition of a desired thickness, the material deposited in the deposition cycle can be oxidized to form a metal oxide or metal silicate. Oxidation may be carried out, for example, by contacting the substrate with a reactant comprising oxygen, such as water, ozone, oxygen atoms, oxygen radicals or oxygen plasma. In this way a dielectric material can be formed from the deposited material on a metal or metallic surface of the substrate relative to a second, different dielectric surface. In some embodiments other treatment steps may be used to form, for example, metal carbides, metal nitrides, or metal silicides from the deposited material.
In some embodiments, a deposition cycle may be repeated at least 10, 25, 50, 100 or more times prior to treatment.
Reaction conditions, including temperature, the substrate surface(s), and the reactants, including the metal halide reactant can be selected to obtain the desired level of selective deposition of a material on the metal or metallic surface relative to the dielectric surface.
In some embodiments, a metal oxide is selectively deposited on a first metal surface comprising a metal oxide surface or first metal surface comprising a dielectric surface relative to a second SiO₂surface at a temperature of about 250 to about 350° C., or about 295° C. to about 315° C.
In some embodiments one or more of the first and second surfaces may be treated in order to enhance deposition on one surface relative to one or more different surfaces. In some embodiments the first metal or metallic surface is treated in order to enhance deposition on the first surface relative to the second surface. In some embodiments the second surface is treated, or deactivated, in order to decrease deposition on the second surface relative to the first surface. In some embodiments the first surface is treated to enhance deposition and the second surface is treated to decrease deposition, thereby increasing selective deposition on the first surface relative to the second surface. In some embodiments no pretreatment is carried out.
In some embodiments the surface comprising dielectric materials such as SiO₂may comprise hydroxyl, or OH-groups which have the effect of making the surface hydrophilic and may be referred to herein as the second surface, dielectric surface, or second dielectric surface. Such OH-group surface terminations can occur naturally when the second surface is exposed to ambient conditions. In some embodiments the dielectric surface may be treated to provide a hydrophilic OH-terminated surface. In some embodiments a hydrophilic OH-terminated surface may be treated to increase the amount of OH-groups on the surface. For example, the dielectric surface may be exposed to H₂O vapor in order to increase the number of OH-groups at the surface. In some embodiments, for example a second surface treatment may include exposing a dielectric surface to a carrier gas that has flowed through a bubbler at a temperature of between about 20° C. and about 50° C. or between about 25° C. and about 40° C. In some embodiments the dielectric surface is exposed to air containing moisture in order to provide a hydrophilic surface that comprises at least some OH-groups. In some embodiments a dielectric surface is not treated prior to deposition.
As mentioned above, in some embodiments the deposition process is an atomic layer deposition (ALD) type process. In some embodiments the deposition process is a thermal ALD process. In some embodiments the deposition process is a vapor deposition process comprising one or more deposition cycles in which a substrate is alternately and sequentially contacted with a first vapor phase halide reactant and a second vapor phase reactant.
In some embodiments the metal halide is a fluoride or chloride of Nb, Ta, Mo, W, V, or Cr. In some embodiments the metal halide is a fluoride or chloride of Nb or Ta.
In some embodiments the first precursor is selected from NbCl₅, NbF₅, TaCl₅, TaF₅, MoF_x(x may be an integer and in some embodiments is 5 or 6), MoCl_x(x may be an integer, and in some embodiments is 5), WF₆, WCl_x(x may be an integer and in some embodiments is 5), VF_x(x may be an integer and in some embodiments is 5), VCl_x(x may be an integer and in some embodiments is 4), and CrF_x(x may be an integer and in some embodiments is 5).
In some embodiments the first precursor is selected from NbCl₅, NbF₅, TaCl₅, and TaF₅.
In some embodiments the first precursor is selected from NbF₅or TaF₅.
In some embodiments the first precursor is selected from NbCl₅or TaCl₅.
In some embodiments the first precursor is NbF₅.
In some embodiments the first precursor is TaF₅.
In some embodiments the first precursor is NbCl₅.
In some embodiments the first precursor is TaCl₅
In some embodiments the first precursor is not a tungsten precursor. For example, in some embodiments the first precursor is not WF₆.
In some embodiments the second precursor comprises a silane, such as monosilane (SiH₄), disilane (Si₂H₆) or trisilane (Si₃H₈). In some embodiments the second precursor is a dialkylsilane, such as diethylsilane. In some embodiments the second precursor comprises OH bonds or provides OH groups to the surface. In some embodiments the second precursor is water. In some embodiments the second precursor is H₂O₂.
In some such embodiments the second reactant may comprise, for example, hydrogen H₂, hydrogen plasma, radicals or atoms. In some embodiments the second reactant may be a silane, such as a monosilane, disilane or trisilane. In some embodiments the second precursor does not comprise plasma.
In some embodiments the material that is selectively deposited on the first surface relative to the second surface form a thin film. In some embodiments the thin film that is selectively deposited is a metal thin film.
In some embodiments the thin film that is selectively deposited is a metal oxide thin film. In some embodiments the metal oxide film is formed using water as a second reactant. In some embodiments a metal oxide film is selectively deposited on a first metal or metallic surface comprising a metal or metallic film relative to a second surface comprising a dielectric film on a substrate by alternately and sequentially contacting the substrate with a first precursor comprising a vapor phase metal halide reactant and second reactant comprising water vapor. In some embodiments the metal halide reactant does not comprise W.
In some embodiments a metal oxide film is selectively deposited on a first surface of a substrate comprising a metal oxide or dielectric surface relative to a second surface of the same substrate comprising an SiO₂surface by alternately and sequentially contacting the substrate with a first precursor comprising a vapor phase metal halide reactant and a second reactant comprising water vapor. For example, in some embodiments a metal oxide such as NbO_xor TaO_xis selectively deposited on a first surface comprising a metal oxide or dielectric surface relative to a second surface comprising SiO₂by alternately and sequentially contacting the substrate with a first precursor comprising a metal halide reactant and a second reactant comprising an oxygen reactant such as water vapor. In particular, in some embodiments NbO_x, such as Nb₂O₅can be deposited on a metal oxide such as tungsten oxide, hafnium oxide, titanium oxide, aluminum oxide, or zirconium oxide from NbF₅and H₂O.
In some embodiments the thin film that is selectively deposited comprises oxygen and one of niobium or tantalum. In some embodiments the thin film that is selectively deposited comprises NbO_xor TaO_x, where x is from about 2 to about 2.75. For simplicity, materials, such as films, may be referred to herein by the formula MO_x, where M is a metal. The formula MO_xindicates that the material comprises primarily a metal, M, and oxygen, however impurities may also be present in such a material. In some embodiments the formula MO_xindicates that the material is an oxide of the metal M. [0048] In some embodiments the thin film that is selectively deposited is a metal silicide. In some embodiments the metal silicide may be formed, for example, by a deposition process as described herein and including a second reactant comprising a disilane or trisilane.
In some embodiments the thin film that is selectively deposited is a metal carbide film. In some embodiments the metal carbide film may be formed by a deposition process as described herein and including a second reactant comprising an alkylsilane.
In some embodiments the thin film that is selectively deposited is a metal nitride.
In some embodiments the substrate is contacted with the first precursor comprising a metal halide at a deposition temperature of above about 225° C. In some embodiments the deposition temperature is above about 250° C., above about 275° C. or above about 300° C. In some embodiments the deposition temperature is between about 250° C. and about 350° C. or between about 295° C. and about 315° C. In some embodiments the temperature is less than about 600° C., less than about 500° C. or less than about 450° C.
In some embodiments a deposition as described herein may become increasingly selective as temperature is increased, for example from about 225° C. to about 300° C., with nearly complete selectivity seen at above about 300° C. in some instances, but not necessarily all instances. Selectivity can be given as a percentage calculated by [(deposition on metal or metallic surface)−(deposition on dielectric surface)]/(deposition on the metal or metallic surface). Deposition can be measured in any of a variety of ways, for example in some embodiments deposition may be given as the measured thickness of the deposited material. In some embodiments deposition may be given as the measured amount of material deposited.
In some embodiments selectivity is greater than about 50%, greater than about 60%, greater than about 70%, greater than about 80%, greater than about 90%, greater than about 95%, greater than about 99% or even greater than about 99.5%.
In some embodiments deposition only occurs on the first surface and does not occur on the second surface. In some embodiments deposition on the first surface of the substrate relative to the second surface of the substrate is at least about 80% selective, which may be selective enough for some particular applications. In some embodiments the deposition on the first surface of the substrate relative to the second surface of the substrate is at least about 50% selective, which may be selective enough for some particular application. However, in some embodiments some deposition may occur on the second surface.
For simplicity, a process may be referred to herein as a selective deposition process because the end result of such a process is a selective amount of deposited material on a first surface relative to a second surface. As such, selectivity as used herein refers to the end result of a deposition process and does not necessarily refer only to selective deposition. In some embodiments selectivity can include, for example, inherent etching during a deposition process which preferentially etches the deposited material on the second surface relative to the deposited material on the first surface, thereby achieving selective formation of the material on the first surface relative to the second surface.
In some embodiments deposition on the first surface of the substrate relative to the second surface of the substrate can be performed up to about 500 deposition cycles before losing the selectivity, or up to about 50 deposition cycles, or up to about 20 deposition cycles, or up to about 10 deposition cycles, or up to about 5 deposition cycles before losing selectivity. In some embodiments even deposition of 1 or 2 cycles before losing selectivity can be useful.
A loss of selectivity can be understood to have occurred when the selectivities mentioned above are no longer met. Depending on the specific circumstances, a loss of selectivity may be considered to have occurred when deposition on the first surface of the substrate relative to the second surface of the substrate is less than about 90% selective, less than about 95% selective, less than about 96%, 97%, 98% or 99% selective or greater.
In some embodiments deposition on the first surface of the substrate relative to the second surface of the substrate can be performed up to a thickness of about 50 nm before losing the selectivity, or up to about 10 nm, or up to about 5 nm, or up to about 3 nm, or up to about 2 nm, or up to about 1 nm before losing selectivity. Depending on the specific circumstances, a loss of selectivity may be considered to have occurred when deposition on the first surface of the substrate relative to the second surface of the substrate is less than about 90% selective, less than about 95% selective, less than about 96%, 97%, 98% or 99% selective or greater.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 10 relative to the second dielectric surface at a thickness of about 0.5 to about 50 nm (10 times less deposition occurs on the second dielectric surface).
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of at least 98% at a thickness of about 0.5 to about 100 nm.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of at least 98% at a thickness of more about 20 nm, more than about 50 nm or more than about 100 nm.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 20 relative to the second dielectric surface at a thickness of about 0.5 to about 50 nm (20 times less deposition occurs on the second dielectric surface).
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 40 relative to the second dielectric surface at a thickness of about 0.5 to about 50 nm (40 times less deposition occurs on the second dielectric surface).
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 15, greater than about 25, or greater than about 50 relative to the second dielectric surface at a thickness of about 0.5 to about 10 nm.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 25 or greater than about 50 relative to the second dielectric surface at a thickness of about 0.5 to about 5 nm.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 10, greater than about 20 or greater than about 40 after from about 1 to 25 deposition cycles, from about 1 to 50 deposition cycles, from about 1 to 100 deposition cycles or from about 1 to 150 deposition cycles.
In some embodiments the film is deposited on the metal or metallic surface with a selectivity of greater than about 10, greater than about 20 or greater than about 40 after from about 1 to 50 deposition cycles, from about 1 to 100 deposition cycles, from about 1 to 250 deposition cycles or from about 1 to 500 deposition cycles.
In some embodiments, no measurable deposition takes place on the second dielectric surface with up to 25, 50, 100 or even 200 cycles. In some embodiments less than 0.1 nm of material is deposited on the second dielectric surface with up to 25, 50, 100 or even 200 cycles. In some embodiments less than 0.3 nm of material is deposited on the second dielectric surface with up to 50, 100, 250 or even 500 deposition cycles.
Embodiments of the invention may be directed to selective deposition of metal oxide on micrometer-scale (or smaller) features during integrated circuit fabrication. In some embodiments the selective deposition can be applied for manufacturing of features having a size less than 100 micrometers, less than 1 micrometer, or less than 200 nm. In the case of selective deposition on metal surfaces, the size of the feature or line width may be less than 1 micrometer, less than 200 nm, less than 100 nm, or less than 50 nm or less than 30 nm or less than 20 nm. One of ordinary skill in the art may recognize that selective deposition on larger features or smaller features and in other contexts is possible using the disclosed methods.
In some embodiments the selectively deposited film may comprise impurities, such as halogens, for example, fluorine, at concentrations of less than about 20 at-%, less than about 10 at-%, less than about 5 at-%, less than about 2 at-%, less than about 1 at-% or less than about 0.5 at-%.
In some embodiments the selectively deposited film has etch selectivity relative to SiO₂, for example in dilute HF. In some embodiments the wet etch selectivity relative to SiO₂is greater than 1:5, greater than 1:10, or greater than 1:20 in dilute HF.
In some embodiments an etch step may be used subsequent to or in the course of deposition to remove material that is non-selectively deposited. In some embodiments the etch process may be a wet etch process or a dry etch process. In some embodiments the etch process is a dry etch process.

ALD Type Processes

ALD type processes are based on controlled, self-limiting surface reactions of precursor chemicals. Gas phase reactions are avoided by alternately and sequentially contacting the substrate with the precursors. Vapor phase reactants are separated from each other on the substrate surface, for example, by removing excess reactants and/or reactant byproducts from the reaction chamber between reactant pulses.
Briefly, a substrate comprising a first metal or metallic surface and second, dielectric surface is heated to a suitable deposition temperature, generally at lowered pressure. Deposition temperatures are discussed above.
The surface of the substrate is contacted with the vapor phase first reactant as discussed above. In some embodiments a pulse of vapor phase first reactant is provided to a reaction space containing the substrate. In some embodiments the substrate is moved to a reaction space containing vapor phase first reactant. In some embodiments conditions are selected such that no more than about one monolayer of the first reactant is adsorbed on the substrate surface in a self-limiting manner. Excess first reactant and reaction byproducts, if any, are removed from the substrate surface, such as by purging with an inert gas or by removing the substrate from the presence of the first reactant.
Purging means that vapor phase precursors and/or vapor phase byproducts are removed from the substrate surface such as by evacuating a chamber with a vacuum pump and/or by replacing the gas inside a reactor with an inert gas such as argon or nitrogen. Typical purging times are from about 0.05 to 20 seconds, between about 1 and 10, or between about 1 and 2 seconds. However, other purge times can be utilized if necessary, such as where highly conformal step coverage over extremely high aspect ratio structures or other structures with complex surface morphology is needed or batch processes with multiple substrates. In selective deposition longer purging times or efficient purging may be used in order to avoid CVD reactions which could possibly ruin the selectivity.
As discussed above, the surface of the substrate is subsequently contacted with a vapor phase second gaseous reactant in each deposition cycle. In some embodiments a pulse of a second gaseous reactant is provided to a reaction space containing the substrate. In some embodiments the substrate is moved to a reaction space containing the vapor phase second reactant. Excess second reactant and gaseous byproducts of the surface reaction, if any, are removed from the substrate surface.
The steps of contacting and removing are repeated until a thin film of the desired thickness has been selectively formed on the first surface of substrate.
Removing excess reactants can include evacuating some of the contents of a reaction space and/or purging a reaction space with helium, nitrogen or another inert gas. In some embodiments purging can comprise turning off the flow of the reactive gas while continuing to flow an inert carrier gas to the reaction space.
The precursors employed in the ALD type processes may be solid, liquid or gaseous materials under standard conditions (room temperature and atmospheric pressure), provided that the precursors are in vapor phase before they are contacted with the substrate surface. Contacting a substrate surface with a vaporized precursor means that the precursor vapor is in contact with the substrate surface for a limited period of time. Typically, the contacting time is from about 0.05 to 10 seconds. However, depending on the substrate type and its surface area, the contacting time may be even higher than 10 seconds. Contacting times can be on the order of minutes in some cases. The optimum contacting time can be determined by the skilled artisan based on the particular circumstances.
The mass flow rate of the precursors can also be determined by the skilled artisan. In some embodiments the flow rate of metal precursors is between about 1 and 1000 sccm without limitation, or between about 100 and 500 sccm.
The pressure in a reaction chamber is typically from about 0.01 to about 20 mbar, or from about 1 to about 10 mbar. However, in some cases the pressure will be higher or lower than this range, as can be determined by the skilled artisan given the particular circumstances.
Examples of suitable reactors that may be used include commercially available ALD equipment such as the F-120® reactor, Pulsar® reactor and Advance® 400 Series reactor, available from ASM America, Inc. of Phoenix, Ariz. and ASM Europe B.V., Almere, Netherlands. In addition to these ALD reactors, many other kinds of reactors capable of ALD growth of thin films, including CVD reactors equipped with appropriate equipment and means for pulsing the precursors can be employed. In some embodiments a flow type ALD reactor is used. In some embodiments reactants are kept separate until reaching the reaction chamber, such that shared lines for the precursors are minimized. However, other arrangements are possible, such as the use of a pre-reaction chamber as described in U.S. patent application Ser. No. 10/929,348, filed Aug. 30, 2004 and Ser. No. 09/836,674, filed Apr. 16, 2001, the disclosures of which are incorporated herein by reference.
The growth processes can optionally be carried out in a reactor or reaction space connected to a cluster tool. In a cluster tool, because each reaction space is dedicated to one type of process, the temperature of the reaction space in each module can be kept constant, which improves the throughput compared to a reactor in which is the substrate is heated up to the process temperature before each run.
A stand-alone reactor can be equipped with a load-lock. In that case, it is not necessary to cool down the reaction space between each run.

Example 1

A deposition process as described herein as carried out in a reaction chamber. NbF₅was used as a first precursor and H₂O was used as a second reactant. The first precursor and second reactant were alternately and sequentially pulsed into the reaction space of a Pulsar® 2000 reactor, wherein the reactants separately contacted various sample substrates at reaction temperature of about 300° C. The reactants were removed from the reaction space between pulses by purging the reaction space. The pulse and purge times used for the first precursor comprising NbF₅were from about 0.5 s to about 2.0 s (pulse) and about 6.0 s (purge), respectively. Pulse and purge times used for the second reactant comprising H₂O were from about 0.5 s to about 2.0 s (pulse) and 5.0 s to about 6.0 s (purge), respectively.
During analysis of the sample substrates, no film growth was observed on native oxide or silicon surfaces of the substrates for deposition processes including at least up to 200 cycles or at least up to 300-500 cycles in the case of substrates including a thermal SiO₂surface. Film growth was observed on a PVD deposited W surfaces of the sample substrates as shown in FIG. 2. Film growth was also observed on sample substrates which included a PVD deposited Co surface and a PVD deposited Ru surface.

Example 2

NbO_xfilms were selectively deposited on a metal oxide surface of a substrate relative to a SiO₂surface using a deposition process as described herein.
A deposition process as described herein as carried out in a reaction chamber. NbF₅was used as a first precursor and H₂O was used as a second reactant. The first precursor and second reactant were alternately and sequentially pulsed into the reaction space of a Pulsar® 2000 reactor, wherein the reactants separately contacted various sample substrates at reaction temperature of about 300° C. Source temperatures for NbF₅and H₂O reactants were 45° C. and about 21° C., respectively. The reactants were removed from the reaction space between pulses by purging the reaction space. The pulse and purge times used for the first precursor comprising NbF₅were from about 0.5 s to about 2.0 s (pulse) and about 6.0 s (purge), respectively. Pulse and purge times used for the second reactant comprising H₂O were from about 0.5 s to about 2.0 s (pulse) and 5.0 s to about 6.0 s (purge), respectively.
Under these deposition conditions, an Nb₂O₅film was observed to be deposited on the first metal oxide surface of the substrate using a deposition process including 500 deposition cycles. The substrate comprised an SiO₂surface with tungsten dots that included a native tungsten oxide surface layer, also referred to herein as tungsten/tungsten oxide areas.
Due to the selectivity of the deposition process, an Nb₂O₅thin film was deposited only on the portions of the substrate surface comprising tungsten/tungsten oxide dots. No film deposition was measured on the SiO₂surface when analyzed via energy-dispersive X-ray spectroscopy (EDX). FIG. 3 shows an SEM image of the resultant Nb₂O₅on the tungsten/tungsten oxide surface. The Nb₂O₅was observed as large crystals on the tungsten/tungsten oxide dots having a thickness of about 80 nm. The thickness of the film was estimated from a film deposited using a similar deposition process with similar conditions on a blanket PVD W coupon.

Claims

We claim:

1. A method for selectively depositing a material on a first metal or metallic surface of a substrate relative to a second dielectric surface of the substrate, the method comprising one or more deposition cycles comprising:

contacting the substrate with a first vapor-phase precursor comprising a metal halide; and

contacting the substrate with a second vapor-phase precursor comprising a silane;

wherein the material is deposited on the first metal or metallic surface relative to the second dielectric surface with a selectivity of above about 50%.

2. The method of claim 1, wherein the metal halide is selected from fluorides or chlorides of Nb, Ta, Mo, W, V and Cr.

3. The method of claim 1, wherein the first precursor is selected from NbCl₅, NbF₅, TaCl₅, TaF₅, MoF_x, MoCl_x, VF_x, VCl_x, and CrF_x, where x is an integer.

4. The method of claim 3, wherein the first precursor is selected from NbCl₅, NbF₅, TaCl₅, and TaF₅.

5. The method of claim 1, wherein the second dielectric surface comprises Si—O bonds.

6. The method of claim 1, wherein the second dielectric surface comprises a non-conductive surface.

7. The method of claim 1, wherein the deposition cycle is repeated until a desired thickness of material is deposited on the first metal or metallic surface.

8. The method of claim 1, wherein the substrate is contacted with the first vapor-phase precursor comprising a metal halide at a temperature equal to or above about 225° C.

9. The method of claim 1, wherein the silane is selected from monosilane, disilane, and trisilane.

10. The method of claim 1, wherein the silane is an alkylsilane.

11. The method of claim 10, wherein the silane is diethylsilane.

12. The method of claim 1, wherein the second vapor-phase precursor does not comprise plasma.

13. The method of claim 1, wherein the material is a metal silicide.

14. The method of claim 13, additionally comprising treating the metal silicide to form a metal silicate.

15. The method of claim 14, wherein treating the metal silicide comprises contacting the metal silicide with a reactant comprising oxygen.

16. The method of claim 15, wherein the reactant comprising oxygen comprises water, ozone, oxygen atoms, oxygen radicals or oxygen plasma.

17. The method of claim 13, wherein the material is not tungsten silicide.

18. The method of claim 13, wherein the metal silicide is deposited on the first metal or metallic surface relative to the second dielectric surface with a selectivity of above about 95%.

19. The method of claim 1, wherein the material is a metal carbide.

20. The method of claim 1, wherein the substrate is contacted with the first vapor-phase precursor comprising a metal halide at a temperature equal to or above about 250° C. and the material is deposited on the first metal or metallic surface relative to the second dielectric surface with a selectivity of above about 95%.