Selective Thermal Atomic Layer Etching

Abstract

The disclosed and claimed invention relates to selective thermal atomic layer etching using a novel series of halogen-free organic acids in conjunction with an oxidizer as a co-reactant to etch metals.

Description

[Technical field]

[0001] The disclosed and claimed invention relates to selective thermal atomic layer etching using a new series of halogen-free organic acids iterated with an oxidizer as a co-reactant to etch metals. Selectivity was demonstrated by thermal etching of copper, cobalt, molybdenum, and tungsten, while nickel, platinum, ruthenium, zirconium oxide, and SiO2 were not etched. [Background technology]

[0002] The miniaturization of features in the semiconductor industry is the primary force behind the continuous improvement of device performance. This trend is expected to continue for at least several more generations of computer chips. For this trend to continue, several technological challenges need to be successfully solved.

[0003] Atomic layer deposition (ALD) is a technique increasingly used in the semiconductor industry, and is currently the deposition method that allows the best control of the amount of material deposited. In ALD, a layer of atoms is deposited on all surfaces exposed to a gas-phase precursor, with the layer being at most as thick as one atomic layer. By sequentially exposing the surface to two different precursors, a layer of material of the desired thickness is deposited. The prototypical example of such a method is the deposition of aluminum oxide (Al2O3) from trimethylaluminum (TMA, Al(CH3)3) and water (H2O), where methane (CH4) is desorbed from these two reactive species. Coating of thin, narrow vias and other high aspect ratio features has been demonstrated many times by ALD in the literature.

[0004] Atomic Layer Etching (ALE or ALEt) can be considered as a layer-by-layer removal of material, whereas ALD is a layer-by-layer addition of material. In ALE, a layer of atoms is removed from any surface exposed to a vapor-phase precursor, ideally at most one atomic layer thick. ALE is performed by sequentially exposing a surface to at least two different precursors, where a first precursor activates a layer of surface atoms, a second precursor promotes the sublimation of this activated layer of atoms, and a third precursor may be used to regenerate the surface to conditions in which the first precursor is active.

[0005] For example, early copper etching processes were disclosed in which copper was chlorinated using a plasma to generate CuCl2. See, e.g., Tamirisa et al., Microelectron., 84, 1055 (2007); Wu et al., J. Electrochem. Soc., 157, H474 (2010) and Hess DW, Workshop on Atomic-Layer-Etch and Clean Technology, San Francisco, Ca (2014). This CuCl2 layer was then etched using a hydrogen plasma, which generated volatile Cu3Cl3. This process could be performed at temperatures as low as 20°C. However, the usefulness of this process for etching copper in small geometries was limited by the rather large profile taper.

[0006] One of the other methods involved etching tungsten. See, for example, Johnson NR and George SM, ACS Applied Materials & Interfaces, 9, 34435 (2017). In this process, and as shown in FIG. 1, tungsten is removed from the tungsten surface with its native oxide layer. (A) a mixture of oxygen and ozone, which oxidizes an additional layer of tungsten to tungsten oxide (surface activation); (B) boron trichloride, which reacts with a portion of the tungsten oxide to produce non-volatile boron oxide and volatile tungsten oxychloride (sublimation of the tungsten-containing species; some tungsten oxide still exists beneath the boron oxide); and (C) hydrogen fluoride, which reacts with boron oxide to produce volatile water vapor and volatile boron trifluoride (regenerating a fresh tungsten oxide surface); The etching could be performed by sequential exposure to (between 128°C and 207°C).

[0007] One other method involved the etching of cobalt. See, for example, Chen et al., J. Vac. Sci. Technol., A35, 05C305 (2017). In this method, etching of cobalt at temperatures above 80° C. was achieved with a high etching rate of 28 Å / cycle, which was far from self-limiting. This process was carried out by removing the cobalt surface. (A) oxygen plasma, which oxidizes the cobalt layers to cobalt oxide (surface activation); and (B) formic acid, which reacts with the cobalt oxide surface species to produce volatile cobalt formate species (sublimation); The study involved sequential exposure to

[0008] An alternative method was used to etch cobalt and copper thin films by using supercritical CO2 and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione under high pressure at 100° C. and 250° C. See, e.g., Rasadujjaman et al., Microelectron. Eng. 153, 5 (2016).

[0009] One other reported method involved etching copper at a temperature above 275° C. with an etching rate of 0.09 nm / cycle. See, for example, Mohimi et al., ECS Journal of Solid State Science and Technology, 7, P491 (2018). This process converts the copper surface into (A) oxygen, which is a mild oxidizing agent and oxidizes the copper layer to copper oxide (surface activation); and (B) acetylacetones, such as 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC), which reacts with copper oxide surface species to produce volatile copper acetylacetonate species (sublimation); The study involved sequential exposure to

[0010] Other alternative methods have been used to etch copper and cobalt films by cycling between alcohols, aldehydes or esters in one step and oxidizing gases in another step, see for example International Publication WO2022050099. In one of these procedures, a cobalt oxide film was etched with tert-butyl alcohol and ozone at 275° C. In one of these procedures, a copper oxide film was etched with tert-butyl alcohol and ozone at 275° C.

[0011] Several methods have been disclosed for removing copper residues using organic acids, alcohols or aldehydes, see, for example, U.S. Patent No. 11,062,914. In one of these procedures, formic acid is used to remove the passivating film formed on copper after chemical mechanical planarization (CMP) with benzotriazole.

[0012] Several methods have been disclosed for removing copper-containing films using adsorption of carboxylic acids, carboxylic anhydrides, esters, alcohols, aldehydes, and ketones, followed by increasing the temperature of the film. See, for example, US 2009 / 0204252 A1. In one of these procedures, formic acid vapor was administered to a sample containing a copper oxide film at room temperature. The sample was then heated to 150° C. to desorb the copper-containing organic complexes derived from the copper oxide film. However, for efficient and uniform processing in semiconductor manufacturing, it may be desirable to maintain a constant substrate temperature.

[0013] Several cobalt etching procedures have also been disclosed. See, for example, Zhao et al., Applied Surface Science, 455, 438 (2018) (Non-Patent Document 8) and Konh et al., Journal of Vacuum Science & Technology A, 37, 021004 (2019) (Non-Patent Document 9). In one of these procedures, the cobalt surface (having a native oxide) is exposed to 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC) to etch the cobalt at temperatures above 377°C. The treated surface is then heated to sublimate the cobalt 1,1,1,5,5,5-hexafluoro-2,4-pentanedione. In one variation shown in FIG. 2, the cobalt is etched by exposing the cobalt surface to HFAC at temperatures above 377°C. (A) chlorine, which oxidizes the cobalt layer to cobalt chloride (surface activation); and (B) acetylacetones, such as 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC), which reacts with cobalt chloride surface species to produce volatile cobalt chloro-acetylacetonate species (sublimation); The material was etched at temperatures in excess of 140° C. by sequential exposure to

[0014] All of the above processes allow for etching of metals using either oxygen plasma or halogen-containing reactants. However, plasmas can be destructive to the substrate and halogens can lead to contamination. Therefore, the new etching chemistry (such as those used in the disclosed and claimed inventions, including but not limited to pivalic acid, isobutyric acid, and / or propionic acid as vaporizers and water, oxygen, and / or hydrogen peroxide as oxidizers) does not use plasma and does not contain halogens. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] WO2022050099 [Patent Document 2] U.S. Pat. No. 11,062,914 [Patent Document 3] US Patent Application Publication No. 2009 / 0204252 [Non-patent literature]

[0016] [Non-Patent Document 1] Tamirisa et al.,Microelectron.,84,1055(2007) [Non-Patent Document 2] ;Wu et al.,J.Electrochem.Soc.,157,H474(2010) [Non-Patent Document 3] Hess DW,Workshop on Atomic-Layer-Etch and Clean Technology,San Francisco,Ca(2014) [Non-Patent Document 4] Johnson NR and George SM,ACS Applied Materials & Interfaces,9,34435(2017) [Non-Patent Document 5] Chen et al., J.Vac.Sci.Technol., A35, 05C305(2017)

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Non - Patent Document 11

Summary of the Invention

[0017] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching to etch metals using one or more halogen-free organic acid vaporizers with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants. In one embodiment, the one or more halogen-free organic acid vaporizers include one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, cyclopropanecarboxylic acid, pentanoic acid, (2E)-but-2-enoic acid, (Z)-2-butenoic acid, and combinations thereof.

[0018] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using pivalic acid as a vaporizing agent together with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants to selectively etch copper, cobalt, molybdenum, and / or tungsten, while nickel, platinum, ruthenium, zirconium oxide, and / or SiO2 are not etched.

[0019] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using isobutyric acid as a vaporizing agent with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants to selectively etch copper, cobalt, molybdenum, and / or tungsten.

[0020] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using propionic acid as a vaporizing agent along with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants to selectively etch copper, cobalt, molybdenum, and / or tungsten.

[0021] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of halogen-free pivalic acid, isobutyric acid, and propionic acid as vaporizers, respectively, with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants. In this way, the disclosed and claimed method avoids any risk of contamination of the substrate with halogen atoms. In one aspect of this embodiment, there are no iodine-containing reactants. In one aspect of this embodiment, there are no bromine-containing reactants. In one aspect of this embodiment, there are no chlorine-containing reactants. In one aspect of this embodiment, there are no fluorine-containing reactants.

[0022] In one aspect of this embodiment, the method does not include 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC) and similar materials.

[0023] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of pivalic acid, isobutyric acid, and propionic acid as vaporizing agents, along with one or more of water, oxygen, and water / oxygen mixtures as oxidizing co-reactants, without including or necessarily requiring the use of a plasma.

[0024] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of pivalic acid, isobutyric acid, and propionic acid as a vaporizing agent, along with water as an oxidizing co-reactant, and further including the use of strong oxidizing agents (e.g., ozone, hydrogen peroxide, nitrous oxide, and oxygen), in which the water co-reactant functions as a mild oxidizing agent.

[0025] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of pivalic acid, isobutyric acid, and propionic acid as vaporizing agents, along with hydrogen peroxide as an oxidizing co-reactant.

[0026] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of pivalic acid, isobutyric acid, and propionic acid as a vaporizing agent, along with an oxygen-containing plasma as an oxidizing co-reactant.

[0027] In one aspect, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching using one or more of pivalic acid, isobutyric acid, and propionic acid as vaporizers, with water, oxygen, and water / oxygen mixtures as oxidizing co-reactants, and which can be performed at low temperatures. In one aspect of this embodiment, etching can proceed at temperatures as low as 110° C., depending on the metal to be etched. In one aspect of this embodiment, copper etching can proceed at temperatures between about 110° C. and about 300° C. In one aspect of this embodiment, cobalt etching is relatively slow at about 300° C. and relatively fast at about 335° C. In one aspect of this embodiment, tungsten etching proceeds slowly at about 335° C. In one aspect of this embodiment, molybdenum etching proceeds slowly at about 335° C.

[0028] This summary section is not intended to identify every aspect and / or radically novel aspect of the disclosed and claimed invention. Instead, this summary provides only a preliminary description of various aspects and corresponding points of novelty over conventional and known techniques. For additional details and / or possible perspectives of the disclosed and claimed invention and aspects, reference is made to the detailed description of the invention and corresponding drawings, which are further described below.

[0029] The order of description of the different steps described herein is presented for clarity. In general, the steps disclosed herein may be performed in any suitable order. Additionally, although different features, techniques, configurations, etc. described herein may each be described in different parts of this specification, it is intended that each of these concepts can be implemented independently of one another or in combination with one another, where appropriate. Thus, the invention as disclosed and claimed can be embodied and viewed in various respects.

[0030] The accompanying drawings provide a further understanding of the disclosed invention, and are incorporated in and constitute a part of this specification, illustrating embodiments of the disclosed invention and, together with the detailed description of the invention, serve to explain the principles of the disclosed invention. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 illustrates a prior art etching process. [Diagram 2] FIG. 2 shows a prior art etching process. [Diagram 3] FIG. 3 illustrates one embodiment of the selective etching process disclosed and claimed.

[0032] definition Unless otherwise stated, the following terms used in the specification and claims have the following meanings in this application.

[0033] For purposes of the disclosed and claimed invention, the numbering convention of the Periodic Table Groups follows the IUPAC Periodic Table of the Elements.

[0034] As used herein, the term "and / or" as used in phrases such as "A and / or B" is intended to include "A and B," "A or B," or "A" and "B."

[0035] The terms "substituent," "residue," "group," and "moiety" may be used interchangeably.

[0036] As used herein, the terms "metal-containing complex" (or more simply, "complex") and "precursor" are used interchangeably and refer to a metal-containing molecule or compound that can be used to produce a metal-containing film by a deposition method such as, for example, ALD or CVD. The metal-containing complex can be deposited, adsorbed, decomposed, delivered and / or distributed onto a substrate or a surface thereof such that a metal-containing film is formed.

[0037] As used herein, the term "metal-containing film" includes elemental metal films, as defined in more detail below, as well as films that contain one or more elements in addition to the metal, such as metal oxide films, metal nitride films, metal silicide films, metal carbide films, and similar films. As used herein, the terms "elemental metal film" and "pure metal film" are used interchangeably and refer to films that consist of or consist essentially of pure metal. For example, an elemental metal film may contain 100% pure metal, or an elemental metal film may contain at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.9%, or at least about 99.99% pure metal, along with one or more impurities. Unless otherwise indicated by context, the term "metal film" is to be construed to mean an elemental metal film.

[0038] As used herein, the term "vapor deposition method" is used to refer to any type of vapor deposition technique, including but not limited to CVD and ALD. In various embodiments, CVD can take the form of conventional (i.e., continuous flow) CVD, liquid injection CVD, or photoassisted CVD. CVD can also take the form of a pulse technique, i.e., pulsed CVD. ALD is used to form metal-containing films by evaporating and / or flowing at least one metal complex disclosed herein onto a substrate surface. For conventional ALD processes, see, for example, George SM, et al. J. Phys. Chem., 1996, 100, 13121-13131. In other embodiments, ALD can take the form of conventional (i.e., pulsed injection) ALD, liquid injection ALD, photoassisted ALD, plasma-assisted ALD, or plasma-enhanced ALD. The term "vapor deposition process" further includes various vapor deposition techniques as described in Chemical Vapour Deposition: Precursors, Processes, and Applications; Jones, AC; Hitchman, ML, Eds., The Royal Society of Chemistry: Cambridge, 2009; Chapter 1, pp. 1-36 (Non-Patent Document 11).

[0039] As used herein, the term "feature" refers to an opening in a substrate that may be defined by one or more sidewalls, a bottom surface, and a top corner. In various aspects, a feature can be a via, a trench, a contact, a dual damascene, etc.

[0040] The terms "about" or "approximately," when used in connection with a measurable variable, refer to the indicated value of the variable and all values ​​of the variable that are within experimental error of the indicated value (e.g., within a 95% confidence limit of the mean) or within a percentage of the indicated value (e.g., ±10%, ±5%), whichever is greater.

[0041] The materials used in the disclosed and claimed methods are preferably substantially free of water. As used herein, "substantially free" as it relates to water means less than 5000 ppm (by weight) as measured by proton NMR or Karl Fischer titration, preferably less than 3000 ppm as measured by proton NMR or Karl Fischer titration, more preferably less than 1000 ppm as measured by proton NMR or Karl Fischer titration, and most preferably less than 100 ppm as measured by proton NMR or Karl Fischer titration.

[0042] The materials used in the disclosed and claimed processes preferably contain metal ions or metals, such as Li + (Li), Na + (Na), K + (K), Mg 2+ (Mg), Ca 2+ (Ca), Al 3+ (Al), Fe 2+ (Fe), Fe 3+ (Fe), Ni 2+ (Ni), Cr 3+ The precursor is also substantially free of Cr, Ti, V, Mg, Mn, Co, Ni, Cu or Zn. These metal ions or metals are potentially present from the raw materials / reactors used to synthesize the precursor. As used herein, the term "substantially free" means less than 5 ppm (by weight), preferably less than 3 ppm, more preferably less than 1 ppm, and most preferably less than 0.1 ppm, when it comes to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr, Ti, V, Mn, Co, Ni, Cu or Zn, as measured by ICP-MS (Inductively Coupled Plasma Mass Spectroscopy).

[0043] Unless otherwise indicated, "alkyl" refers to a C1-C6 alkyl group that can be linear or branched (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, and the like), or cyclic (e.g., cyclohexyl, cyclopropyl, cyclopentyl, and the like).20 The term "alkyl" refers to a hydrocarbon group, the alkyl portion of which may be substituted or unsubstituted as described below. 20 It refers to such moieties having carbon atoms. For structural reasons, linear alkyl is understood to start from C1, while branched alkyl and cyclic alkyl are understood to start from C3. Furthermore, the moieties derived from alkyl described below, such as alkyloxy and perfluoroalkyl, are understood to have the same carbon number range unless otherwise stated. If the length of the alkyl group is specified differently from the above, the above definition of alkyl still applies in that it includes all the above types of alkyl moieties, and the above structural considerations regarding the minimum carbon number for a given type of alkyl group still apply.

[0044] Halo or halide refers to a halogen, F, Cl, Br, or I, attached to an organic moiety by one bond. In some embodiments, the halogen is F. In other embodiments, the halogen is Cl.

[0045] Alkyl halides are fully or partially halogenated C1-C 20 Refers to alkyl.

[0046] Perfluoroalkyl refers to linear, cyclic or branched saturated alkyl as defined above in which all of the hydrogens have been replaced by fluorine (eg, trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoroisopropyl, perfluorocyclohexyl, and the like).

[0047] The materials used in the disclosed and claimed methods are preferably substantially free of any organic impurities originating from the raw materials used during synthesis or from by-products produced during synthesis. Examples include, but are not limited to, alkanes, alkenes, alkynes, dienes, ethers, esters, acetates, amines, ketones, amides, aromatics, and the like. As used herein, the term "free" of organic impurities means less than 1000 ppm as measured by GC (gas chromatography), preferably less than 500 ppm (by weight) as measured by GC, and most preferably less than 100 ppm (by weight) as measured by GC or other analytical methods for evaluation. Importantly, the precursors preferably have a purity of 98% by weight or more, more preferably 99% by weight or more, as measured by GC, when used as precursors for depositing ruthenium-containing films.

[0048] The section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described. All references or portions of references cited herein, including but not limited to patents, patent applications, papers, books, and treatises, are incorporated herein in their entirety for all purposes. In the event that the definitions of terms in any of the references and similar materials incorporated herein conflict with those herein, the definitions herein shall control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to be limiting with respect to the invention as set forth in the claims. The objectives, features, advantages and concepts of the disclosed invention will be apparent to those skilled in the art from the description set forth herein, and further, the disclosed invention can be easily implemented by those skilled in the art based on the description set forth herein. Any description of a "preferred embodiment" and / or examples showing a preferred mode for carrying out the disclosed invention is included for illustrative purposes and is not intended to limit the scope of the claims.

[0050] It will also be apparent to those skilled in the art that various modifications may be made in the practice of the disclosed invention based on the aspects described herein without departing from the spirit and scope of the invention disclosed herein.

[0051] In one aspect, the disclosed and claimed invention relates to a method for isotropic thermal ALE of metals, including copper, cobalt, molybdenum and / or tungsten, comprising, consisting essentially of, or consisting of the steps of: (i) an oxidation step, which involves exposing the metal surface to one or more oxidizing and / or hydroxylating co-reactants (or "oxidizing agents" or "surface modifiers") to produce an oxidized and / or hydroxylated surface; (ii) a first purge step; (iii) a vaporization step, comprising exposing the oxidized and / or hydroxylated surface to one or more vaporizing agents (or "volatizers") to generate volatile metal-organic species; and (iv) A second purge step.

[0052] In yet another aspect of this embodiment, the method consists essentially of steps (i), (ii), (iii) and (iv). In yet another aspect of this embodiment, the method consists of steps (i), (ii), (iii) and (iv). The steps of the method can be repeated as necessary to remove the desired thickness of metal oxide. In yet another aspect, any of the above embodiments can further comprise, consist essentially of or consist of a post-treatment step (v), which may be added to remove impurities remaining on the surface after a desired number of cycles.

[0053] As previously described, the disclosed and claimed invention relates to a method for selective thermal atomic layer etching comprising an etching cycle that comprises, consists essentially of, or consists of exposing a metal surface to one or more halogen-free organic acids and one or more oxidizing co-reactants during the cycle. A single cycle of the disclosed and claimed method comprises: (Step 1) n +(Step 2) m comprising, consisting essentially of, or consisting of In the formula, n and m are each independently 1 to 20 and represent the number of times that step 1 and step 2 are performed within a single cycle (i.e., the number of iterations); Step 1 involves, in sequence, exposing a metal surface to one or more oxidizing co-reactants (Step 1A) and purging with an inert gas (Step 1B); and Step 2 involves sequentially exposing the metal surface to one or more halogen-free organic acids (Step 2A) and purging with an inert gas (Step 2B).

[0054] Therefore, n can also be understood to be equal to the number of times steps 1A and 1B are performed sequentially within step 1, and m can also be understood to be equal to the number of times steps 2A and 2B are performed sequentially within step 2.

[0055] In particular, the disclosed and claimed invention relates to a thermal atomic layer etching (ALE) process carried out in a reactor for selectively etching metal surfaces, comprising the steps of: Step 1, which involves sequentially performing steps 1A and 1B: Step 1A includes exposing the metal surface to an oxidizing vapor including one or more of water vapor, oxygen, ozone, nitrous oxide, hydrogen peroxide, oxygen plasma, and combinations thereof; and Step 1B includes purging the oxidizing vapor with an inert gas; and Step 2, which involves sequentially performing steps 2A and 2B: Step 2A, comprising exposing the metal surface to one or more halogen-free organic acid vaporizers; and Step 2B, comprising purging the one or more halogen-free organic acid vaporizers with an inert gas; Here, one cycle of the process is represented by the formula (Step 1): n +(Step 2) m wherein m and n are each independently 1 to 20.

[0056] In one embodiment, each repetition of step 1 alternates within each cycle with a repetition of step 2. In another embodiment, all repetitions of step 1 are initiated and completed within each cycle before initiating and completing a repetition of step 2.

[0057] In one embodiment, n is the same as m. In one embodiment, n is different from m.

[0058] In one embodiment, n is 1. In one embodiment, n is 2. In one embodiment, n is 3. In one embodiment, n is 4. In one embodiment, n is 5. In one embodiment, n is 6. In one embodiment, n is 7. In one embodiment, n is 8. In one embodiment, n is 9. In one embodiment, n is 10. In one embodiment, n is 11. In one embodiment, n is 12. In one embodiment, n is 13. In one embodiment, n is 14. In one embodiment, n is 15. In one embodiment, n is 16. In one embodiment, n is 17. In one embodiment, n is 18. In one embodiment, n is 19. In one embodiment, n is 20.

[0059] In one embodiment, m is 1. In one embodiment, m is 2. In one embodiment, m is 3. In one embodiment, m is 4. In one embodiment, m is 5. In one embodiment, m is 6. In one embodiment, m is 7. In one embodiment, m is 8. In one embodiment, m is 9. In one embodiment, m is 10. In one embodiment, m is 11. In one embodiment, m is 12. In one embodiment, m is 13. In one embodiment, m is 14. In one embodiment, m is 15. In one embodiment, m is 16. In one embodiment, m is 17. In one embodiment, m is 18. In one embodiment, m is 19. In one embodiment, m is 20.

[0060] In one embodiment, n is 1 and m is 1. In one embodiment, n is 2 and m is 2. In one embodiment, n is 3 and m is 3. In one embodiment, n is 4 and m is 4. In one embodiment, n is 5 and m is 5. In one embodiment, n is 6 and m is 6. In one embodiment, n is 7 and m is 7. In one embodiment, n is 8 and m is 8. In one embodiment, n is 9 and m is 9. In one embodiment, n is 10 and m is 10. In one embodiment, n is 11 and m is 11. In one embodiment, n is 12 and m is 12. In one embodiment, n is 13 and m is 13. In one embodiment, n is 14 and m is 14. In one embodiment, n is 15 and m is 15. In one embodiment, n is 16 and m is 16. In one embodiment, n is 17 and m is 17. In one embodiment, n is 18 and m is 18. In one embodiment, n is 19 and m is 19. In one embodiment, n is 20 and m is 20.

[0061] FIG. 3 illustrates one embodiment of the disclosed and claimed selective etching process using water vapor.

[0062] Number of cycles The disclosed and claimed methods can include any number of cycles as desired. In one embodiment, the number of cycles is about 20 to about 5000. In one embodiment, the number of cycles is about 20 to about 2200. In one embodiment, the number of cycles is about 50 to about 5000. In one embodiment, the number of cycles is about 50 to about 2500. In one embodiment, the number of cycles is about 50 to about 1500. In one embodiment, the number of cycles is about 50 to about 1000. In one embodiment, the number of cycles is about 50 to about 750. In one embodiment, the number of cycles is about 50 to about 500. In one embodiment, the number of cycles is about 50 to about 300. In one embodiment, the number of cycles is about 50 to about 200. In one embodiment, the number of cycles is about 150 to about 4000. In one embodiment, the number of cycles is about 200 to about 3000. In one embodiment, the number of cycles is about 250 to about 2500. In one embodiment, the number of cycles is about 350 to about 2000. In one embodiment, the number of cycles is about 450 to about 1700. In one embodiment, the number of cycles is about 500 to about 1500. In one embodiment, the number of cycles is about 750 to about 1250. In one embodiment, the number of cycles is about 250 to about 1000. In one embodiment, the number of cycles is about 500 to about 1000. In one embodiment, the number of cycles is about 750 to about 1000.

[0063] In one embodiment, the number of cycles is about 50. In one embodiment, the number of cycles is about 100. In one embodiment, the number of cycles is about 125. In one embodiment, the number of cycles is about 150. In one embodiment, the number of cycles is about 175. In one embodiment, the number of cycles is about 200. In one embodiment, the number of cycles is about 250. In one embodiment, the number of cycles is about 300. In one embodiment, the number of cycles is about 350. In one embodiment, the number of cycles is about 400. In one embodiment, the number of cycles is about 450. In one embodiment, the number of cycles is about 500. In one embodiment, the number of cycles is about 750. In one embodiment, the number of cycles is about 1000. In one embodiment, the number of cycles is about 1250. In one embodiment, the number of cycles is about 1500. In one embodiment, the number of cycles is about 1750. In one embodiment, the number of cycles is about 2000. In one embodiment, the number of cycles is about 2250. In one embodiment, the number of cycles is about 2500. In one embodiment, the number of cycles is about 2750. In one embodiment, the number of cycles is about 3000. In one embodiment, the number of cycles is about 3250. In one embodiment, the number of cycles is about 3500. In one embodiment, the number of cycles is about 4000. In one embodiment, the number of cycles is about 4500. In one embodiment, the number of cycles is about 5000.

[0064] Chamber (reactor) temperature In one embodiment, the reactor comprises a reactor chamber including a body and a heatable lid, an external heater and an internal heater (pedestal).

[0065] External Heater In one embodiment, the chamber external heater is set to about 100°C to about 400°C. In one embodiment, the chamber external heater is set to about 140°C. In one embodiment, the chamber external heater is set to about 160°C. In one embodiment, the chamber external heater is set to about 200°C. In one embodiment, the chamber external heater is set to about 225°C. In one embodiment, the chamber external heater is set to about 250°C. In one embodiment, the chamber external heater is set to about 280°C. In one embodiment, the chamber external heater is set to about 300°C. In one embodiment, the chamber external heater is set to about 325°C. In one embodiment, the chamber external heater is set to about 350°C. In one embodiment, the chamber external heater is set to about 375°C. In one embodiment, the chamber external heater is set to about 400°C. In one embodiment, the reactor chamber includes an external heater heated to a temperature of about 100°C to about 300°C and an internal heater heated to a temperature of about 100°C to about 350°C.

[0066] Lid heater (i.e. process chamber gas supply area) In one embodiment, the chamber lid heater is set at about 100°C to about 200°C. In one embodiment, the chamber lid heater is set at about 100°C. In one embodiment, the chamber lid heater is set at about 130°C. In one embodiment, the chamber lid heater is set at about 150°C. In one embodiment, the chamber lid heater is set at about 200°C.

[0067] Internal heater (i.e., process chamber or sample pedestal) In one embodiment, the heater inside the chamber is set to about 100°C to about 350°C. In one embodiment, the heater inside the chamber is set to about 140°C. In one embodiment, the heater inside the chamber is set to about 150°C. In one embodiment, the heater inside the chamber is set to about 160°C. In one embodiment, the heater inside the chamber is set to about 170°C. In one embodiment, the heater inside the chamber is set to about 180°C. In one embodiment, the heater inside the chamber is set to about 190°C. In one embodiment, the heater inside the chamber is set to about 200°C. In one embodiment, the heater inside the chamber is set to about 225°C. In one embodiment, the heater inside the chamber is set to about 250°C. In one embodiment, the heater inside the chamber is set to about 275°C. In one embodiment, the heater inside the chamber is set to about 300°C. In one embodiment, the heater inside the chamber is set to about 325°C. In one embodiment, the heater inside the chamber is set to about 335°C.

[0068] metal As previously described, the disclosed and claimed methods provide selective thermal etching on certain metal substrates. In one embodiment, the disclosed and claimed methods selectively etch substrates comprising one or more of copper, cobalt, molybdenum, and tungsten in preference to nickel, platinum, ruthenium, zirconium oxide, and / or SiO2. In one embodiment, the disclosed and claimed methods selectively etch substrates comprising copper. In one embodiment, the disclosed and claimed methods selectively etch substrates comprising cobalt. In one embodiment, the disclosed and claimed methods selectively etch substrates comprising molybdenum. In one embodiment, the disclosed and claimed methods selectively etch substrates comprising tungsten. In one embodiment, the disclosed and claimed methods do not etch or do not substantially etch substrates comprising one or more of nickel, platinum, ruthenium, zirconium oxide, and / or SiO2.

[0069] Selective Etching Step Step 1: Oxidation sequence Step 1 comprises, consists essentially of, or consists of, sequentially exposing a metal surface to one or more oxidizing co-reactants (Step 1A) and purging with an inert gas (Step 1B), said one or more oxidizing co-reactants being preferably provided as vapor.

[0070] Step 1A: Oxidizing Co-Reactant Exposure In step 1A, the metal surface is exposed to one or more oxidizing co-reactants, preferably provided as a vapor (i.e., "oxidizing vapor"), such as water vapor; water vapor in co-flow with an oxidizing agent, such as oxygen, ozone, nitrous oxide, nitric oxide, or hydrogen peroxide; or an oxidizing vapor composed of oxygen, ozone, nitric oxide, oxygen plasma, or hydrogen peroxide, but without co-flow water vapor, for a suitable duration and temperature sufficient to oxidize the surface of the metal substrate.

[0071] In one aspect, the oxidizing steam includes one or more of water vapor, oxygen, ozone, nitrous oxide, nitric oxide, hydrogen peroxide, and oxygen plasma, and combinations thereof. In one aspect of this aspect, the oxidizing steam includes water vapor. In one aspect of this aspect, the oxidizing steam includes oxygen. In one aspect of this aspect, the oxidizing steam includes ozone. In one aspect of this aspect, the oxidizing steam includes nitrous oxide. In one aspect of this aspect, the oxidizing steam includes oxygen plasma. In one aspect of this aspect, the oxidizing steam includes hydrogen peroxide. In one aspect of this aspect, the oxidizing steam includes water vapor and one or more of oxygen, ozone, nitrous oxide, hydrogen peroxide, and oxygen plasma. In one aspect of this aspect, the oxidizing steam includes water vapor and oxygen. In one aspect of this aspect, the oxidizing steam includes water vapor and ozone. In one aspect of this aspect, the oxidizing steam includes water vapor and nitrous oxide. In one aspect of this embodiment, the oxidizing steam includes water vapor and oxygen plasma. In one aspect of this embodiment, the oxidizing steam includes water vapor and hydrogen peroxide. In one aspect of this embodiment, the oxidizing steam includes water vapor and two or more of oxygen, ozone, nitrous oxide, and hydrogen peroxide.

[0072] time In one embodiment, the step 1A oxidizing steam exposure is from about 0.25 seconds to about 6 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 0.25 seconds to about 2 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 0.5 seconds to about 5 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 5 seconds to about 15 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 0.25 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 0.5 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 1 second. In one embodiment, the step 1A oxidizing steam exposure is from about 2 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 4 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 5 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 6 seconds. In one embodiment, the step 1A oxidizing steam exposure is from about 7 seconds. In one embodiment, the Step 1A oxidizing steam exposure is for about 10 seconds. In one embodiment, the Step 1A oxidizing steam exposure is for about 12 seconds. In one embodiment, the Step 1A oxidizing steam exposure is for about 15 seconds.

[0073] Temperature (oxidizing vapor source) In one embodiment, in step 1A, the oxidizing vapor source is not actively heated but is maintained at an ambient temperature of about 20° C. to about 35° C. In one embodiment, in step 1A, the oxidizing vapor source is heated and maintained at about 20° C. to about 30° C. In one embodiment, in step 1A, the oxidizing vapor source is heated and maintained at about 30° C. to about 35° C. In one embodiment, in step 1A, the oxidizing vapor source is heated and maintained at about 25° C. In one embodiment, in step 1A, the oxidizing vapor source is heated and maintained at about 30° C. In one embodiment, in step 1A, the oxidizing vapor source is heated and maintained at about 35° C.

[0074] Temperature (water vapor source) In one embodiment, in step 1A, the water source is cooled and maintained at about 0°C to about 5°C. In one embodiment, in step 1A, the water source is cooled and maintained at about 5°C to about 10°C. In one embodiment, in step 1A, the water source is cooled and maintained at about 10°C to about 15°C. In one embodiment, in step 1A, the water source is cooled and maintained at about 15°C to about 20°C. In one embodiment, in step 1A, the water source is cooled and maintained at about 20°C to about 25°C. In one embodiment, in step 1A, the water vapor source is heated and maintained at about 20°C to about 25°C. In one embodiment, in step 1A, the water vapor is heated and maintained at about 25°C to about 30°C. In one embodiment, in step 1A, the water vapor source is heated and maintained at about 30°C to about 35°C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 35° C. to about 40° C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 40° C. to about 45° C.

[0075] In one embodiment, in step 1A, the water vapor source is cooled to and maintained at about 0° C. In one embodiment, in step 1A, the water vapor source is cooled to and maintained at about 5° C. In one embodiment, in step 1A, the water vapor source is cooled to and maintained at about 10° C. In one embodiment, in step 1A, the water vapor source is cooled to and maintained at about 15° C. In one embodiment, in step 1A, the water vapor source is cooled to and maintained at about 20° C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 20° C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 25° C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 30° C. In one embodiment, in step 1A, the water vapor source is heated to and maintained at about 40° C. In one embodiment, in step 1A, the water vapor source is heated and maintained at about 45°C.

[0076] In one embodiment, the water vapor source temperature is maintained substantially constant, hi one embodiment, the water vapor source temperature is varied.

[0077] Temperature (hydrogen peroxide source) In one embodiment, in step 1A, the hydrogen peroxide source is cooled and maintained at about 0°C to about 5°C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled and maintained at about 5°C to about 10°C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled and maintained at about 10°C to about 15°C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled and maintained at about 15°C to about 20°C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled and maintained at about 20°C to about 25°C. In one embodiment, in step 1A, the hydrogen peroxide source is heated and maintained at about 20°C to about 25°C. In one embodiment, in step 1A, the hydrogen peroxide source is heated and maintained at about 25°C to about 30°C. In one embodiment, in step 1A, the hydrogen peroxide source is heated and maintained at about 30°C to about 40°C.

[0078] In one embodiment, in step 1A, the hydrogen peroxide source is cooled to and maintained at about 0° C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled to and maintained at about 5° C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled to and maintained at about 10° C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled to and maintained at about 15° C. In one embodiment, in step 1A, the hydrogen peroxide source is cooled to and maintained at about 20° C. In one embodiment, in step 1A, the hydrogen peroxide source is heated to and maintained at about 20° C. In one embodiment, in step 1A, the hydrogen peroxide source is heated to and maintained at about 25° C. In one embodiment, in step 1A, the hydrogen peroxide source is heated to and maintained at about 30° C. In one embodiment, in step 1A, the hydrogen peroxide source is heated to and maintained at 40° C.

[0079] In one embodiment, the hydrogen peroxide source temperature is maintained substantially constant, hi one embodiment, the hydrogen peroxide source temperature is varied.

[0080] Chamber (reactor) pressure Oxidizing Vapor Pressure In one embodiment, the oxidizing steam is fed into the chamber through one inlet, while the inert gas is fed into the chamber through another inlet. In one embodiment, the oxidizing steam is fed into the chamber through one inlet, while an additional oxidizing gas is fed into the chamber through another inlet, and the inert gas is fed into the chamber through a third inlet. In one embodiment, the total pressure in the chamber during the oxidizing steam feed is about 0.1 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing steam feed is about 0.5 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing steam feed is about 0.5 Torr to about 2.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing steam feed is about 0.5 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing steam feed is about 0.5 Torr to about 0.75 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 1.0 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 1.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 2.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 10.0 Torr to about 25.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 10.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 25.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 50.0 Torr to about 75.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 75.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor delivery is from about 1.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor delivery is from about 10.0 Torr to about 100.0 Torr.

[0081] In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.1 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.25 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.5 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.75 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 2.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 3.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 4.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 15.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 20.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 75.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 100.0 Torr.

[0082] Water Vapor Pressure In one embodiment, water vapor is fed into the chamber through one inlet, while an inert gas is fed into the chamber through the other inlet. In one embodiment, the total pressure in the chamber during the water vapor feed is about 0.1 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 0.5 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 0.5 Torr to about 2.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 0.5 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 0.5 Torr to about 0.75 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 1.0 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor feed is about 1.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 2.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 10.0 Torr to about 25.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 10.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 25.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 50.0 Torr to about 75.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 75.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 1.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the supply of water vapor is about 10.0 Torr to about 100.0 Torr.

[0083] In one embodiment, the total pressure in the chamber during the water vapor supply is about 0.1 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 0.25 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 0.5 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 0.75 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 1.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 2.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 3.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 4.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 5.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 10.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 15.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 20.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 50.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 75.0 Torr. In one embodiment, the total pressure in the chamber during the water vapor supply is about 100.0 Torr.

[0084] Mixed / Combined Oxidizing Vapor Pressure In one embodiment, water vapor is fed into the chamber through one inlet, while additional oxidizing gas is fed into the chamber through another inlet to form a mixed or combined oxidizing vapor, and an inert gas is fed into the chamber through a third inlet. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 0.1 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 0.5 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 0.5 Torr to about 2.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 0.5 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 0.5 Torr to about 0.75 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor feed is about 1.0 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 1.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 2.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 10.0 Torr to about 25.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 10.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 25.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 50.0 Torr to about 75.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is from about 75.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor delivery is from about 1.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor delivery is from about 10.0 Torr to about 100.0 Torr.

[0085] In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.1 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.25 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.5 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 0.75 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 1.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 2.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 3.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 4.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 5.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 10.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 15.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 20.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 50.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 75.0 Torr. In one embodiment, the total pressure in the chamber during the oxidizing vapor supply is about 100.0 Torr.

[0086] In yet another aspect of the above embodiment and aspects thereof, the additional oxidizing gas includes one or more of oxygen, ozone, nitrous oxide, and hydrogen peroxide. In yet another aspect of the above embodiment and aspects thereof, the additional oxidizing gas includes oxygen. In yet another aspect of the above embodiment and aspects thereof, the additional oxidizing gas includes ozone. In yet another aspect of the above embodiment and aspects thereof, the additional oxidizing gas includes nitrous oxide. In yet another aspect of the above embodiment and aspects thereof, the additional oxidizing gas includes hydrogen peroxide.

[0087] Supply method In one embodiment, the oxidizing steam is provided by vapor-draw. In one embodiment, the oxidizing steam is provided with the aid of a carrier gas. In one embodiment, the oxidizing steam is provided by bubbling an inert gas into water. In one embodiment, the oxidizing steam is provided as a gas (i.e., without bubbling into water). In one embodiment, the oxidizing steam is provided simultaneously with additional oxidizing steam.

[0088] Step 1B: Inert gas purge Purge Gas Any suitable inert purge gas can be used when performing step 1B. In one embodiment, the purge gas comprises argon. In one embodiment, the purge gas comprises nitrogen.

[0089] time In one embodiment, the step 1B purge time is about 0.5 seconds to about 30 seconds. In one embodiment, the step 1B purge time is about 1 second to about 5 seconds. In one embodiment, the step 1B purge time is about 10 seconds to about 30 seconds. In one embodiment, the step 1B purge time is about 0.5 seconds to about 10 seconds. In one embodiment, the step 1B purge time exposure is about 1 second to about 7 seconds. In one embodiment, the step 1B purge time exposure is about 7 seconds to about 10 seconds. In one embodiment, the step 1B purge time exposure is about 10 seconds to about 20 seconds. In one embodiment, the step 1B purge time exposure is about 20 seconds to about 30 seconds. In one embodiment, the step 1B purge time exposure is about 0.25 seconds. In one embodiment, the step 1B purge time exposure is about 0.5 seconds. In one embodiment, the step 1B purge time exposure is about 1 second. In one embodiment, the Step 1B purge time exposure is about 2 seconds. In one embodiment, the Step 1B purge time exposure is about 3 seconds. In one embodiment, the Step 1B purge time exposure is about 4 seconds. In one embodiment, the Step 1B purge time exposure is about 5 seconds. In one embodiment, the Step 1B purge time exposure is about 6 seconds. In one embodiment, the Step 1B purge time exposure is about 7 seconds. In one embodiment, the Step 1B purge time exposure is about 8 seconds. In one embodiment, the Step 1B purge time exposure is about 9 seconds. In one embodiment, the Step 1B purge time exposure is about 10 seconds. In one embodiment, the Step 1B purge time exposure is about 12 seconds. In one embodiment, the Step 1B purge time exposure is about 15 seconds. In one embodiment, the Step 1B purge time exposure is about 17 seconds. In one embodiment, the Step 1B purge time exposure is about 20 seconds. In one embodiment, the Step 1B purge time exposure is about 25 seconds. In one embodiment, the Step 1B purge time exposure is about 30 seconds.

[0090] flow rate When performing step 1B, the purge gas is flowed at between about 1 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at between about 3 sccm and about 8 sccm. In one embodiment, the purge gas is flowed at between about 100 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at between about 50 sccm and about 500 sccm. In one embodiment, the purge gas is flowed at between about 500 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at about 1 sccm. In one embodiment, the purge gas is flowed at about 2 sccm. In one embodiment, the purge gas is flowed at about 3 sccm. In one embodiment, the purge gas is flowed at about 4 sccm. In one embodiment, the purge gas is flowed at about 5 sccm. In one embodiment, the purge gas is flowed at about 6 sccm. In one embodiment, the purge gas flows at about 7 sccm. In one embodiment, the purge gas flows at about 8 sccm. In one embodiment, the purge gas flows at about 9 sccm. In one embodiment, the purge gas flows at about 10 sccm. In one embodiment, the purge gas flows at about 9 sccm. In one embodiment, the purge gas flows at about 10 sccm. In one embodiment, the purge gas flows at about 50 sccm. In one embodiment, the purge gas flows at about 100 sccm. In one embodiment, the purge gas flows at about 200 sccm. In one embodiment, the purge gas flows at about 300 sccm. In one embodiment, the purge gas flows at about 500 sccm. In one embodiment, the purge gas flows at about 750 sccm. In one embodiment, the purge gas is flowed at about 1000 sccm. In one embodiment, the purge gas is flowed at about 1250 sccm. In one embodiment, the purge gas is flowed at about 1500 sccm. In one embodiment, the purge gas is flowed at about 1750 sccm. In one embodiment, the purge gas is flowed at about 2000 sccm.

[0091] Step 2: Vapor Exposure Sequence Step 2 comprises, consists essentially of, or consists, in sequence, of exposing the modified metal surface to one or more vaporizing agents (Step 2A) and purging with an inert gas (Step 2B), wherein the one or more vaporizing agents comprise, consist essentially of, or consist of a halogen-free organic acid or a mixture of halogen-free organic acids.

[0092] In one embodiment, the one or more vaporizing agents include one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, cyclopropanecarboxylic acid, pentanoic acid, (2E)-but-2-enoic acid, (Z)-2-butenoic acid, and combinations thereof. In one embodiment, the one or more vaporizing agents include one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, and combinations thereof. In one embodiment, the one or more vaporizing agents include one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, and combinations thereof. In one embodiment, the one or more vaporizing agents include one or more of propionic acid, isobutyric acid, pivalic acid, and combinations thereof. In one aspect of this embodiment, the one or more vaporizers include propionic acid. In one aspect of this embodiment, the one or more vaporizers include isobutyric acid. In one aspect of this embodiment, the one or more vaporizers include pivalic acid. In one aspect of this embodiment, the one or more vaporizers include acetic acid. In one aspect of this embodiment, the one or more vaporizers include butanoic acid. In one aspect of this embodiment, the one or more vaporizers include acrylic acid. In one aspect of this embodiment, the one or more vaporizers include methacrylic acid. In one aspect of this embodiment, the one or more vaporizers include 2-methylbutanoic acid. In one aspect of this embodiment, the one or more vaporizers include 3-methylbutanoic acid. In one aspect of this embodiment, the one or more vaporizers include 3-butenoic acid. In one aspect of this embodiment, the one or more vaporizers include cyclopropanecarboxylic acid. In one aspect of this embodiment, the one or more vaporizers include pentanoic acid. In one aspect of this embodiment, the one or more vaporizing agents include (2E)-but-2-enoic acid. In one aspect of this embodiment, the one or more vaporizing agents include (Z)-2-butenoic acid. In one aspect of this embodiment, the one or more vaporizing agents include a mixture of one or more of propionic acid, isobutyric acid, and pivalic acid. In one aspect of this embodiment, the one or more vaporizing agents include a mixture of two or more of propionic acid, isobutyric acid, and pivalic acid.In one aspect of this embodiment, the one or more vaporizing agents include a mixture of halogen-free organic acids including one or more of propionic acid, isobutyric acid, and pivalic acid.

[0093] Step 2A: Vaporizer Exposure time In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 0.25 seconds to about 15 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 0.25 seconds to about 1 second. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 0.5 seconds to about 2 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 2 seconds to about 15 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 0.25 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 0.5 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 1 second. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 2 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 3 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 4 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 5 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 6 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 8 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 10 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 12 seconds. In one embodiment, the exposure to the one or more vaporizers in step 2A is for about 15 seconds.

[0094] Chamber (reactor) temperature In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 50°C to about 100°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 55°C to about 95°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 60°C to about 90°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 65°C to about 85°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 70°C to about 80°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 50°C. In one embodiment, in step 2A, the one or more vaporizing agents are at about 55°C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 60° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 65° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 70° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 75° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 80° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 85° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 90° C. In one embodiment, in step 2A, the one or more vaporizing agents are heated and maintained at about 95° C. In one embodiment, in Step 2A, the one or more vaporizing agents are heated and maintained at about 100°C.

[0095] Supply method In one embodiment, the one or more vaporizers are supplied in a once-through manner without the assistance of a carrier gas, as described below. In another embodiment, the one or more vaporizers are supplied in a once-through manner with the assistance of a carrier gas, as described below.

[0096] In one embodiment, the one or more vaporizers are delivered and "trapped," where the reactor chamber is closed and the one or more vaporizers are "trapped" in the reactor. In one aspect of this embodiment, the one or more vaporizers are delivered using a carrier gas (e.g., nitrogen or argon), as described below. In one aspect of this embodiment, the deposition chamber outlet is closed prior to delivery of the vaporizers, such that the one or more vaporizers remain trapped in the chamber. In one aspect of this embodiment, the reactor outlet is kept closed for a time period from approximately 0.1 seconds to approximately 10 seconds to keep the one or more vaporizers trapped in the reactor, thereby maximizing its effect before opening the reactor to vent gases.

[0097] Chamber (reactor) pressure In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 0.1 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 0.5 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 0.5 Torr to about 2.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 0.5 Torr to about 1.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 0.5 Torr to about 0.75 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 1.0 Torr to about 5.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 1.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 2.0 Torr to about 10.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 10.0 Torr to about 25.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 10.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 25.0 Torr to about 50.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 50.0 Torr to about 75.0 Torr. In one embodiment, the total pressure in the chamber during the supply of pivalic acid is about 75.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during the supply of the one or more vaporizers is about 1.0 Torr to about 100.0 Torr. In one embodiment, the total pressure in the chamber during delivery of the one or more vaporizers is from about 10.0 Torr to about 100.0 Torr.

[0098] In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 0.1 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 0.25 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 0.5 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 0.75 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 1.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 2.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 3.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 4.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 5.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 10.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 15.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 20.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 50.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 75.0 Torr. In one embodiment, the total pressure in the chamber during the delivery of the one or more vaporizers is about 100.0 Torr.

[0099] Optional Carrier Gas Any suitable inert carrier gas can be used when performing step 2B, if desired. In one embodiment, the carrier gas comprises argon. In one embodiment, the carrier gas comprises nitrogen.

[0100] Step 2B: Inert gas purge Purge Gas Any suitable inert purge gas can be used when performing step 2B. In one embodiment, the purge gas comprises argon. In one embodiment, the purge gas comprises nitrogen.

[0101] time In one embodiment, the step 2B purge time is about 0.5 seconds to about 75 seconds. In one embodiment, the step 2B purge time is about 0.5 seconds to about 10 seconds. In one embodiment, the step 2B purge time exposure is about 1 second to about 7 seconds. In one embodiment, the step 2B purge time exposure is about 1 second to about 5 seconds. In one embodiment, the step 2B purge time exposure is about 10 seconds to about 75 seconds. In one embodiment, the step 2B purge time exposure is about 0.25 seconds. In one embodiment, the step 2B purge time exposure is about 0.5 seconds. In one embodiment, the step 2B purge time exposure is about 1 second. In one embodiment, the step 2B purge time exposure is about 2 seconds. In one embodiment, the step 2B purge time exposure is about 3 seconds. In one embodiment, the step 2B purge time exposure is about 4 seconds. In one embodiment, the step 2B purge time exposure is about 5 seconds. In one embodiment, the step 2B purge time exposure is about 6 seconds. In one embodiment, the step 2B purge time exposure is about 7 seconds. In one embodiment, the step 2B purge time exposure is about 8 seconds. In one embodiment, the step 2B purge time exposure is about 9 seconds. In one embodiment, the step 2B purge time exposure is about 10 seconds. In one embodiment, the step 2B purge time exposure is about 15 seconds. In one embodiment, the step 2B purge time exposure is about 20 seconds. In one embodiment, the step 2B purge time exposure is about 25 seconds. In one embodiment, the step 2B purge time exposure is about 30 seconds. In one embodiment, the step 2B purge time exposure is about 40 seconds. In one embodiment, the step 2B purge time exposure is about 50 seconds. In one embodiment, the step 2B purge time exposure is about 60 seconds. In one embodiment, the step 2B purge time exposure is about 75 seconds.

[0102] In one embodiment, the final purge time before beginning a new cycle is extended (i.e., extended purge). In one embodiment, the extended purge time is from about 30 seconds to about 60 seconds. In one embodiment, the extended purge time is from about 30 seconds to about 45 seconds. In one embodiment, the extended purge time is about 30 seconds. In one embodiment, the extended purge time is about 45 seconds. In one embodiment, the extended purge time is about 60 seconds.

[0103] flow rate When performing step 2B, the purge gas is flowed at between about 1 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at between about 3 sccm and about 8 sccm. In one embodiment, the purge gas is flowed at between about 100 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at between about 50 sccm and about 500 sccm. In one embodiment, the purge gas is flowed at between about 500 sccm and about 2000 sccm. In one embodiment, the purge gas is flowed at about 1 sccm. In one embodiment, the purge gas is flowed at about 2 sccm. In one embodiment, the purge gas is flowed at about 3 sccm. In one embodiment, the purge gas is flowed at about 4 sccm. In one embodiment, the purge gas is flowed at about 5 sccm. In one embodiment, the purge gas is flowed at about 6 sccm. In one embodiment, the purge gas flows at about 7 sccm. In one embodiment, the purge gas flows at about 8 sccm. In one embodiment, the purge gas flows at about 9 sccm. In one embodiment, the purge gas flows at about 10 sccm. In one embodiment, the purge gas flows at about 9 sccm. In one embodiment, the purge gas flows at about 10 sccm. In one embodiment, the purge gas flows at about 50 sccm. In one embodiment, the purge gas flows at about 100 sccm. In one embodiment, the purge gas flows at about 200 sccm. In one embodiment, the purge gas flows at about 300 sccm. In one embodiment, the purge gas flows at about 500 sccm. In one embodiment, the purge gas flows at about 750 sccm. In one embodiment, the purge gas is flowed at about 1000 sccm. In one embodiment, the purge gas is flowed at about 1250 sccm. In one embodiment, the purge gas is flowed at about 1500 sccm. In one embodiment, the purge gas is flowed at about 1750 sccm. In one embodiment, the purge gas is flowed at about 2000 sccm.

[0104] film The disclosed and claimed invention further includes membranes produced by the methods described herein.

[0105] In one embodiment, the film etched by the methods described herein has trenches, vias, or other topographical features with an aspect ratio of about 0 to about 60. In yet another aspect of this embodiment, the aspect ratio is about 0 to about 0.5. In yet another aspect of this embodiment, the aspect ratio is about 0.5 to about 1. In yet another aspect of this embodiment, the aspect ratio is about 1 to about 50. In yet another aspect of this embodiment, the aspect ratio is about 1 to about 40. In yet another aspect of this embodiment, the aspect ratio is about 1 to about 30. In yet another aspect of this embodiment, the aspect ratio is about 1 to about 20. In yet another aspect of this embodiment, the aspect ratio is about 1 to about 10. In yet another aspect of this embodiment, the aspect ratio is about 0.1. In yet another aspect of this embodiment, the aspect ratio is about 0.2. In yet another aspect of this embodiment, the aspect ratio is about 0.3. In yet another aspect of this embodiment, the aspect ratio is about 0.4. In yet another aspect of this embodiment, the aspect ratio is about 0.5. In yet another aspect of this embodiment, the aspect ratio is about 0.6. In yet another aspect of this embodiment, the aspect ratio is about 0.8. In yet another aspect of this embodiment, the aspect ratio is about 1. In yet another aspect of this embodiment, the aspect ratio is greater than about 1. In yet another aspect of this embodiment, the aspect ratio is greater than about 2. In yet another aspect of this embodiment, the aspect ratio is greater than about 5. In yet another aspect of this embodiment, the aspect ratio is greater than about 10. In yet another aspect of this embodiment, the aspect ratio is greater than about 15. In yet another aspect of this embodiment, the aspect ratio is greater than about 20. In yet another aspect of this embodiment, the aspect ratio is greater than about 30. In yet another aspect of this embodiment, the aspect ratio is greater than about 40. In yet another aspect of this embodiment, the aspect ratio is greater than about 50. In the above embodiment and still another aspect of these aspects, the metal includes copper, cobalt, molybdenum, and tungsten.In yet another aspect of the above embodiment or these aspects, the metal comprises copper. In yet another aspect of the above embodiment or these aspects, the metal comprises cobalt. In yet another aspect of the above embodiment or these aspects, the metal comprises molybdenum. In yet another aspect of the above embodiment or these aspects, the metal comprises tungsten.

[0106] In another aspect, a film etched by the method described herein has a resistivity between about 1 μΩ.cm and about 250 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 1 μΩ.cm to about 5 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 3 μΩ.cm to 4 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 5 μΩ.cm to about 10 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 10 μΩ.cm to about 50 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 50 μΩ.cm to about 100 μΩ.cm. In yet another aspect of this aspect, the film has a resistivity of about 100 μΩ.cm to about 250 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 1 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 2 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 3 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 4 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 5 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 7.5 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 10 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 15 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 20 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 30 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 40 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 50 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 60 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 80 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 100 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 150 μΩ.cm.In yet another aspect of this embodiment, the film has a resistivity of about 200 μΩ.cm. In yet another aspect of this embodiment, the film has a resistivity of about 250 μΩ.cm. In the above embodiment and yet another aspect of these aspects, the metal includes copper, cobalt, molybdenum, and tungsten. In the above embodiment and yet another aspect of these aspects, the metal includes copper. In the above embodiment and yet another aspect of these aspects, the metal includes cobalt. In the above embodiment and yet another aspect of these aspects, the metal includes molybdenum. In the above embodiment and yet another aspect of these aspects, the metal includes tungsten.

[0107] Another aspect of the disclosed and claimed invention is a method of using one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, cyclopropanecarboxylic acid, pentanoic acid, (2E)-but-2-enoic acid, (Z)-2-butenoic acid, and combinations thereof as halogen-free organic vaporizers, together with one or more of water vapor, oxygen, ozone, nitrous oxide, hydrogen peroxide, and oxygen plasma, and combinations thereof as oxidizing vapors, for selective thermal atomic layer etching of metal substrates including one or more of copper, cobalt, molybdenum, and tungsten. EXAMPLES

[0108] More specific embodiments of the present disclosure, as well as experimental results in support of such embodiments, are described below. These examples are provided below to more fully explain the disclosed invention, and should not be construed as limiting the disclosed invention in any manner.

[0109] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed invention and the specific examples provided herein without departing from the spirit or scope of the disclosed invention. Thus, the disclosed invention, including the description provided by way of the following examples, is intended to cover modifications and variations of the disclosed invention that come within the scope of any claims and their equivalents.

[0110] Materials and Methods: Experiments for etch conditions I-XIV and examples 1-18 were carried out in a cross-flow ALD system capable of accommodating wafer sizes up to 8 inches in diameter. Etch conditions XV-XVII and examples 19-24 were carried out in an ALD system equipped with a funnel lid (detailed below). Pivalic acid, isobutyric acid, and propionic acid were obtained from Millipore Sigma. Etching condition I: Single dose of pivalic acid and single dose of water Etching conditions II: Single dose of pivalic acid Etching Condition III: Three Doses of Pivalic Acid and Three Doses of Water Etching condition IV: Three doses of pivalic acid and a single dose of water Etching condition V: Single dose of pivalic acid and three doses of water Etching condition VI: Three doses of pivalic acid (at a relatively high temperature of 85° C.) and three doses of water Etching Condition VII: Two Doses of Water Etching condition VIII: Three doses of pivalic acid (at a relatively high temperature of 85° C.) and a single dose of water Etching Condition IX: Three doses of pivalic acid (at a relatively low temperature of 60° C.; trapped mode; delivered using nitrogen carrier gas) and two doses of water. Etching condition X: Three doses of pivalic acid (at a relatively low temperature of 60° C.; trapping method; delivered using nitrogen carrier gas), and a single dose of water Etching condition XI: No pivalic acid or water, heat treatment (treated at either 120°C or 170°C) Etching condition XII: Heat treatment using water (treatment at 120°C) Etching condition XIII: Heat treatment using pivalic acid (treatment at 120°C) Etching condition XIV: Single dose of pivalic acid (administered at 75° C.; delivered using nitrogen carrier gas) and single dose of water Etching condition XV: A single dose of pivalic acid at a relatively low temperature (50°C) Etching conditions XVI: Single dose of pivalic acid and single dose of water + oxygen Etching Condition XVII: Single dose of pivalic acid and either single, double or triple doses of water-oxygen Etching Conditions XVIII: Single Dose of Pivalic Acid and Three Dose of Hydrogen Peroxide Etching conditions XIX: A single dose of isobutyric acid and two or four doses of oxygen. Etching conditions XX: One dose of isobutyric acid and four doses of water plus oxygen Etching conditions XXI: Single dose of propionic acid and two or four doses of oxygen Etching conditions XXII: Single dose of propionic acid and double doses of water plus oxygen

[0111] Example 1: Cobalt ALE under standard conditions In this example, ALE was performed under Etch Condition I with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 350 cycles, each cycle including a single dose of pivalic acid and a single dose of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH (delivered by a Vaber draw; heated and maintained at approximately 80 °C (uncorrected temperature), resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (d) Purge with 5 sccm of nitrogen for 5 s.

[0112] After 350 cycles, (i) 17 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.049 Å / cycle, (ii) a maximum of 29 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.083 Å / cycle, and (iii) 19 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.054 Å / cycle.

[0113] Example 2: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition II for 350 cycles with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. Each etch cycle included: (a) 0.5 s exposure to pivalic acid (CH3)3C-COOH (delivered via a Vaber draw while heated and maintained at 80 °C (unmodified temperature), resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (b) Then, purge with 5 sccm of nitrogen for 5 seconds.

[0114] After 350 cycles, (i) approximately 0 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), (ii) approximately 3 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), and (iii) approximately 8 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.). Given the degree of uncertainty in such low etching measurements, these measurements can be interpreted as no cobalt etching occurring.

[0115] Example 3: Cobalt ALE under standard conditions In this example, ALE was performed under Etch Condition I with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 500 cycles, each cycle including a single dose of pivalic acid and a single dose of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH (delivered by a Vaber draw; heated and maintained at approximately 80 °C (uncorrected temperature), resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (d) Purge with 5 sccm of nitrogen for 5 s.

[0116] After 350 cycles, (i) 27-30 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.054-0.060 Å / cycle, (ii) 37-41 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.074-0.082 Å / cycle, and (iii) 28-40 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.056-0.080 Å / cycle. The etch ranges shown reflect that this experiment was repeated three times and found to be repeatable.

[0117] Example 4: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition III with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 500 cycles, each cycle including three doses of pivalic acid and three doses of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (f) purge with 5 sccm of nitrogen for 5 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (h) purge with 5 sccm nitrogen for 1 s; (i) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (j) purge with 5 sccm nitrogen for 1 s; (k) 0.5 second exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (l) Purge with 5 sccm of nitrogen for 5 s.

[0118] After 500 cycles, (i) 56 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.112 Å / cycle, (ii) 60 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.120 Å / cycle, and (iii) 59 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.118 Å / cycle.

[0119] Example 5: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition III with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including three doses of pivalic acid and three doses of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (f) purge with 5 sccm of nitrogen for 5 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (h) purge with 5 sccm nitrogen for 1 s; (i) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (j) purge with 5 sccm nitrogen for 1 s; (k) 0.5 second exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (l) Purge with 5 sccm of nitrogen for 5 s.

[0120] After 250 cycles, (i) 34 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.136 Å / cycle, (ii) 40 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.160 Å / cycle, and (iii) 40 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.160 Å / cycle.

[0121] Example 6: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition IV with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including three doses of pivalic acid and a single dose of water, as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (f) purge with 5 sccm nitrogen for 1 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (h) Purge with 5 sccm of nitrogen for 5 s.

[0122] After 250 cycles, (i) 40 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.160 Å / cycle, (ii) 44 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.176 Å / cycle, and (iii) 44 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.176 Å / cycle.

[0123] Example 7: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition IV with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including a single dose of pivalic acid and three doses of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (f) purge with 5 sccm of nitrogen for 5 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (h) Purge with 5 sccm of nitrogen for 5 s.

[0124] After 250 cycles, (i) 9 Å of cobalt was etched from the cobalt coupon placed near the entrance of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.036 Å / cycle, (ii) 10 Å of cobalt was etched from the cobalt coupon placed near the center of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.040 Å / cycle, and (iii) 12 Å of cobalt was etched from the cobalt coupon placed near the exit of the process chamber (heated to about 280° C.), corresponding to an etch rate of 0.048 Å / cycle.

[0125] Example 8: A series of cobalt ALEs under standard conditions In this example, ALE was performed under etch condition VI with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for between 60 and 1000 cycles, with each cycle including three doses of pivalic acid (at an elevated temperature of 85° C.) and three doses of water, as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (f) purge with 5 sccm of nitrogen for 5 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 1.20–1.40 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (h) purge with 5 sccm nitrogen for 1 s; (i) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 1.20–1.40 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (j) purge with 5 sccm nitrogen for 1 s; (k) 0.5 second exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 1.20-1.40 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (l) Purge with 5 sccm of nitrogen for 5 s.

[0126] After this process, various amounts of cobalt were etched from the cobalt coupons placed near the center of the process chamber (heated to about 335° C.), corresponding to various etch rates as shown in Table 1 below. As the number of etch cycles increased, the etch rate decreased. This can be explained by the fact that there was less and less residual cobalt to etch. The total thickness of the cobalt film before etching was about 120 Å.

[0127] [Table 1]

[0128] Example 9: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition IV with the process chamber external heater set at 300° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including three doses of pivalic acid and a single dose of water, as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (f) purge with 5 sccm nitrogen for 1 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike of 0.930–0.960 Torr) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (h) Purge with 5 sccm of nitrogen for 5 s.

[0129] After 250 cycles, 14-20 Å of cobalt was etched from a cobalt coupon placed near the center of the process chamber (heated to approximately 300° C.), reflecting an etch rate of 0.056-0.080 Å / cycle.

[0130] Example 10: Cobalt ALE under standard conditions In this example, ALE was performed under etch condition III with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including three doses of pivalic acid and a single dose of water (with various preheat temperatures) as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (f) purge with 5 sccm of nitrogen for 5 s; (g) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80, 85 or 90 °C (unmodified temperature), respectively, delivered by a Vaber draw, resulting in a pressure spike) (Note: pivalic acid was used in a flow-through fashion without carrier gas assistance); (h) purge with 5 sccm nitrogen for 1 s; (i) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80, 85 or 90 °C (unmodified temperature) respectively and delivered via a Vaber draw, resulting in a pressure spike) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (j) purge with 5 sccm nitrogen for 1 s; (k) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 80, 85 or 90 °C (unmodified temperature), respectively, delivered by a Vaber draw, resulting in a pressure spike) (Note: pivalic acid was used in a flow-through mode without carrier gas assistance); and (l) Purge with 5 sccm of nitrogen for 5 s.

[0131] After 250 cycles with pivalic acid heated to 80° C., (i) 34 Å of cobalt was etched from a cobalt coupon placed near the reactor inlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.136 Å / cycle, (ii) 40 Å of cobalt was etched from a cobalt coupon placed near the reactor center of the process chamber (heated to about 335° C.), reflecting an etch rate of 0.160 Å / cycle, and (iii) 40 Å of cobalt was etched from a cobalt coupon placed near the reactor outlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.160 Å / cycle.

[0132] After 250 cycles with pivalic acid heated to 85° C., (i) 40 Å of cobalt was etched from a cobalt coupon placed near the reactor inlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.160 Å / cycle, (ii) 40 Å of cobalt was etched from a cobalt coupon placed near the reactor center of the process chamber (heated to about 335° C.), reflecting an etch rate of 0.160 Å / cycle, and (iii) 51 Å of cobalt was etched from a cobalt coupon placed near the reactor outlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.204 Å / cycle.

[0133] After 250 cycles with pivalic acid heated to 90° C., (i) 37 Å of cobalt was etched from a cobalt coupon placed near the reactor inlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.148 Å / cycle, (ii) 45 Å of cobalt was etched from a cobalt coupon placed near the reactor center of the process chamber (heated to about 335° C.), reflecting an etch rate of 0.180 Å / cycle, and (iii) 51 Å of cobalt was etched from a cobalt coupon placed near the reactor outlet of the process chamber (heated to about 300° C.), reflecting an etch rate of 0.204 Å / cycle.

[0134] Example 11: Cobalt heat treatment under standard conditions In this example, ALE was performed under etch condition VII with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including two doses of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; and (d) Purge with 5 sccm of nitrogen for 30 s.

[0135] After 250 cycles, 0 Å of cobalt was etched from the cobalt coupon located near the center of the process chamber (heated to approximately 335° C.).

[0136] Example 12: Tungsten, copper, cobalt, polished and unpolished molybdenum ALE under standard conditions In this example, ALE was performed under etch condition VIII with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 1,000 cycles, with each cycle including three doses of pivalic acid (preheated to 85° C.) and a single dose of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 6 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike. (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas.); (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 s exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); (f) purge with 5 sccm nitrogen for 1 s; (g) 0.5 second exposure to pivalic acid (CH3)3C-COOH (heated and maintained at 85 °C (unmodified temperature) and delivered via a Vaber draw, resulting in a pressure spike) (Note: pivalic acid was used in a flow-through fashion without the assistance of a carrier gas); and (h) Purge with 5 sccm of nitrogen for 5 s.

[0137] After 1,000 cycles with pivalic acid heated to 85° C., (i) 11 Å of tungsten was etched from a tungsten coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.011 Å / cycle, (ii) 40 Å of molybdenum was etched from a polished molybdenum coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.040 Å / cycle, and (iii) 10 Å of molybdenum was etched from a polished molybdenum coupon placed near the center of the reactor of the process chamber (heated to about 335° C.). (iv) 85 Å of molybdenum was etched from an unpolished molybdenum coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.085 Å / cycle; (iv) 101-104 Å of cobalt was etched from a cobalt coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.1 Å / cycle; and (v) 220-1548 Å of copper was etched from a copper coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.220-1.548 Å / cycle.

[0138] Example 13: Tungsten, copper, cobalt, polished and unpolished molybdenum ALE under standard conditions In this example, ALE was performed under etching condition IX with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250 cycles, each cycle including three doses of pivalic acid (preheated to 60° C., used in scavenging mode and delivered with nitrogen carrier gas) and two doses of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 s exposure to water vapor, HO, delivered by a Baer Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (d) purge with 5 sccm of nitrogen for 1 s; (e) 0.5 second exposure to pivalic acid (CH3)3C-COOH, maintained at 60 °C (unmodified temperature) and fed with N2 assist, resulting in a pressure spike of 0.930-0.960 Torr. (Note: the deposition chamber outlet was closed prior to feeding pivalic acid to ensure that the acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (f) purge with 5 sccm nitrogen for 0.1 s; (g) 0.5 second exposure to pivalic acid (CH3)3C-COOH (maintained at 60 °C (unmodified temperature) and N2 assisted delivery resulting in a pressure spike of 0.930-0.960 Torr). (Note: the deposition chamber outlet was closed prior to delivery of pivalic acid to ensure that the pivalic acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (h) purge with 5 sccm nitrogen for 0.1 s; (i) a 0.5 second exposure to pivalic acid (CH3)3C-COOH (maintained at 60 °C (unmodified temperature) and N2 assisted delivery resulting in a pressure spike of 0.930-0.960 Torr) (Note: the deposition chamber outlet was closed prior to delivery of pivalic acid to ensure that the pivalic acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional 1 second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor); and (i) Purge with 5 sccm of nitrogen for 5 seconds.

[0139] After 250 cycles with pivalic acid heated to 60° C., (i) 53 Å of tungsten was etched from a tungsten coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.212 Å / cycle, (ii) 65 Å of molybdenum was etched from a polished molybdenum coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.260 Å / cycle, and (iii) 53 Å of molybdenum was etched from a polished molybdenum coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.250 Å / cycle. (iv) 103-113 Å of cobalt was etched from a cobalt coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 0.41-0.45 Å / cycle, and (v) 965 Å of copper was etched from a copper coupon placed near the center of the reactor of the process chamber (heated to about 335° C.), corresponding to an etch rate of 3.86 Å / cycle.

[0140] Example 14: Copper ALE under standard conditions In this example, ALE was performed under etch condition X with the process chamber external heater set at 280° C. and the process chamber internal heater set at 335° C. for 250, 175, 320, 350 or 700 cycles, with each cycle including three doses of pivalic acid (preheated to 60° C., used in a capture mode and delivered with nitrogen carrier gas) and a single dose of water, as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 1 s; (c) 0.5 second exposure to pivalic acid (CH3)3C-COOH, maintained at 60 °C (unmodified temperature) and fed with N2 assist, resulting in a pressure spike of 0.930-0.960 Torr. (Note: the deposition chamber outlet was closed prior to feeding pivalic acid to ensure that the acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (d) purge with 5 sccm of nitrogen for 0.1 s; (e) 0.5 second exposure to pivalic acid (CH3)3C-COOH, maintained at 60 °C (unmodified temperature) and fed with N2 assist, resulting in a pressure spike of 0.930-0.960 Torr. (Note: the deposition chamber outlet was closed prior to feeding pivalic acid to ensure that the acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (f) purge with 5 sccm nitrogen for 0.1 s; (g) 0.5 second exposure to pivalic acid (CH3)3C-COOH (maintained at 60 °C (unmodified temperature) and N2 assisted delivery resulting in a pressure spike of 0.930-0.960 Torr) (Note: the deposition chamber outlet was closed prior to delivery of pivalic acid to ensure that the pivalic acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); and (h) Purge with 5 sccm of nitrogen for 5 s.

[0141] The RMS of the copper sample in this example before the etching process was 0.73 nm (roughness) as measured by AFM.

[0142] After 250 cycles with pivalic acid heated to 60° C., 130 Å of copper was etched from a copper coupon placed near the center of the reactor in the process chamber (heated to approximately 200° C.), corresponding to an etch rate of 0.52 Å / cycle.

[0143] After 175 cycles with pivalic acid heated to 60° C., (i) 30-90 Å of copper was etched from the copper coupon placed near the center of the reactor in the process chamber (heated to about 180° C.), corresponding to an etch rate of 0.17-0.52 Å / cycle, (ii) 13-67 Å of copper was etched from the copper coupon placed near the center of the reactor in the process chamber (heated to about 160° C.), corresponding to an etch rate of 0.07-0.38 Å / cycle, and (iii) 13-67 Å of copper was etched from the copper coupon placed near the center of the reactor in the process chamber (heated to about 140° C.). (iv) 18-37 Å of copper was etched from a copper coupon placed near the reactor center of the process chamber (heated to approximately 130° C.), corresponding to an etch rate of 0.11-0.21 Å / cycle, and (v) 21-25 Å of copper was etched from a copper coupon placed near the reactor center of the process chamber (heated to approximately 120° C.), corresponding to an etch rate of 0.12-0.14 Å / cycle.

[0144] After 350 cycles with pivalic acid heated to 60°C, 25-45 Å of copper was etched from a copper coupon placed near the center of the reactor of the process chamber (heated to approximately 120°C), corresponding to an etch rate of 0.07-0.12 Å / cycle, and after this treatment the copper film had an RMS of 2.41 nm (roughness) as measured by AFM, and some film pitting was observable after the etching process.

[0145] After 700 cycles with pivalic acid heated to 60° C., 52-60 Å of copper was etched from a copper coupon placed near the reactor center of the process chamber (heated to approximately 120° C.), corresponding to an etch rate of 0.08-0.09 Å / cycle, and after this treatment the copper film had an RMS of 10.79 nm (roughness) as measured by AFM, with film pitting and island formation being very widespread after this etching protocol.

[0146] After 320 cycles with pivalic acid heated to 60°C, 11-23 Å of copper was etched from the copper coupon placed near the reactor center of the process chamber (heated to about 110°C), corresponding to an etch rate of 0.034-0.07 Å / cycle, and after this treatment the copper film had an RMS of 1.67 nm (roughness) as measured by AFM, and film pitting was barely detectable after this etching treatment.

[0147] The above results are summarized in Table 2. Table 2 also shows that the copper films etched at 200° C., 180° C. and 160° C. became insulating, while the copper films etched at temperatures below 140° C. remained electrically conductive.

[0148] [Table 2]

[0149] Example 15: Copper heat treated under standard conditions In this example, ALE was performed under etching condition XI with the process chamber external heater and the process chamber internal heater each set to the same temperature (either 120° C. or 170° C.).

[0150] In one test, a copper sample was heated to 120°C for 3.5 hours. After this treatment, very few pinholes and no tall island formation were observed, but the surface morphology was relatively rough; the copper film had an RMS of 1.49 nm (roughness) as measured by AFM. The copper was not etched.

[0151] In another test, a copper sample was heated to 170° C. for 70 minutes. After this treatment, numerous pinholes and numerous newly formed tall islands were observed. The copper was not etched.

[0152] Example 16: Copper heat treated under standard conditions In this example, ALE was performed under etching condition XII with the process chamber external heater set at 120° C. and the process chamber internal heater set at 120° C. for 350 cycles, each cycle including a single dose of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (approximately 30 °C), resulting in a pressure spike of 0.650–0.700 Torr; and (b) Purge with 5 sccm of nitrogen for 36.9 s.

[0153] After 350 cycles, no pinholes or tall island formation were observed, but the surface morphology was relatively rough; the copper film had an RMS of 2.04 nm (roughness) as measured by AFM. The copper was not etched.

[0154] Example 17: Copper heat treated under standard conditions In this example, ALE was performed under etching condition XII with the process chamber external heater set at 120° C. and the process chamber internal heater set at 120° C. for 350 cycles, each cycle including a single dose of pivalic acid as follows: (a) 0.5 second exposure to pivalic acid (CH3)3C-COOH, maintained at 60 °C (unmodified temperature) and fed with N2 assist, resulting in a pressure spike of 0.930-0.960 Torr. (Note: the deposition chamber outlet was closed prior to feeding pivalic acid to ensure that the acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (b) purge with 5 sccm nitrogen for 0.1 s; (c) 0.5 second exposure to pivalic acid (CH3)3C-COOH, maintained at 60 °C (unmodified temperature) and fed with N2 assist, resulting in a pressure spike of 0.930-0.960 Torr. (Note: the deposition chamber outlet was closed prior to feeding pivalic acid to ensure that the acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); (d) purge with 5 sccm of nitrogen for 0.1 s; (e) 0.5 second exposure to pivalic acid (CH3)3C-COOH (maintained at 60 °C (unmodified temperature) and N2 assisted delivery resulting in a pressure spike of 0.930-0.960 Torr) (Note: the deposition chamber outlet was closed prior to delivery of pivalic acid to ensure that the pivalic acid remained trapped in the chamber. After this pulse of pivalic acid, the reactor outlet was kept closed for an additional second to keep the pivalic acid trapped in the reactor (to maximize its effect). The reactor vacuum was then released to vent the gases from the reactor.); and (f) Purge with 5 sccm of nitrogen for 5 s.

[0155] After 350 cycles, some pinholes were observed, but no tall island formation was observed; the copper film had an RMS of 1.54 nm (roughness) as measured by AFM, which was smoother than the film exposed to a water-only pulse. Between 8 Å and 24 Å of copper was etched.

[0156] Example 18: Copper ALE under standard conditions In this example, ALE was performed under etch condition XIV with the process chamber external heater set at 140° C. and the process chamber internal heater set at 140° C. for 700, 1750 or 3000 cycles, each cycle including a single dose of pivalic acid (preheated to 75° C.) and a single dose of water as follows: (a) 0.5 s exposure to water vapor, HO, delivered by a Vaber Draw while maintained at a temperature slightly above room temperature (30 °C), resulting in a pressure spike of 0.650–0.700 Torr; (b) purge with 5 sccm of nitrogen for 5 s; (c) 0.5 s exposure to pivalic acid (CH3)3C-COOH, heated and maintained at 75 °C (unmodified temperature) and supplied with N2 (Note: pivalic acid was used in a flow-through manner without carrier gas support); and (d) Purge with 5 sccm nitrogen for 10 s.

[0157] The RMS of the copper sample before etching was 0.73 nm (roughness) as measured by AFM.

[0158] After 700 cycles, 20-21 Å of copper was etched and the film resistivity was 7.2-7.9 μΩ.cm after etching. A few pinholes were detectable and no tall islands of crystalline copper were detectable. The roughness of this copper film after etching was 1.255 nm.

[0159] After 1750 cycles and an initial base pressure of 0.5 Torr, (i) on the coupons near the reactor inlet, 32 Å of copper was etched, with a film resistivity of 9 μΩ.cm and a roughness of 4.8 nm, (ii) on the coupons near the reactor center, 20-50 Å of copper was etched, with a film resistivity of 9-19 μΩ.cm and a roughness ranging from 1.7 to 5.4 nm, and (iii) on the coupons near the reactor outlet, 64 Å of copper was etched, with a film resistivity of 67 μΩ.cm and a roughness of 4.3 nm. Pinholes were detectable on all coupons, but no tall islands of crystalline copper were detectable.

[0160] After 1750 cycles using an initial base pressure of 0.75 Torr, (i) on the coupon near the reactor inlet, 30 Å of copper was etched, with a film resistivity of 7.3 μΩ.cm and roughness ranging from 2.8 to 3.5 nm, (ii) on the coupon near the reactor center, 58 Å of copper was etched, with a film resistivity of 35 μΩ.cm and roughness ranging from 3.1 to 5.4 nm, and (iii) on the coupon near the reactor outlet, 56 Å of copper was etched, with a film resistivity of 55 μΩ.cm and roughness of 4.5 nm. Pinholes were detectable on all coupons, but no tall islands of crystalline copper were detectable.

[0161] After 3000 cycles using an initial base pressure of 0.17 Torr, (i) on the coupon near the reactor inlet, 39-44 Å of copper was etched, the film resistivity was 10-11 μΩ.cm, and the roughness was 4.0 nm, (ii) on the coupon near the reactor center, 82 Å of copper was etched, the copper film became insulating, and the roughness was 3.3 nm, and (iii) on the coupon near the reactor outlet, 75 Å of copper was etched, the copper film became insulating, and the roughness was 3.8 nm. Pinholes were detectable on all coupons, but tall islands of crystalline copper were not detectable.

[0162] After 1750 cycles of water pulsing only, using an initial base pressure of 0.18 Torr, (i) the coupon near the reactor inlet had no copper etching and a roughness of 3.15 nm, (ii) the coupon near the reactor center had no copper etching and a roughness of 1.8 nm, and (iii) the coupon near the reactor outlet had no copper etching and a roughness of 3.9 nm. Pinholes were detectable on all coupons, as well as tall islands of crystalline copper.

[0163] The above data for Example 18 are summarized in Tables 3 and 4.

[0164] [Table 3]

[0165] [Table 4]

[0166] As described above, the experiments for etch conditions XV-XVII and examples 19-24 were conducted in an ALD system equipped with a funnel lid. The ALD system was capable of accommodating wafer sizes up to 12 inches in diameter. The ALD system was equipped with a heated pedestal on which the wafer was placed. For each experiment, a 44 mm x 44 mm test substrate was placed on a 300 mm carrier wafer. The test substrate was prepared by physical vapor deposition (PVD) of 250 Å titanium on a 200 mm wafer, followed by PVD of 500 Å copper on the titanium layer. The 200 mm wafer was then cleaved into 44 mm x 44 mm test substrates. Pivalic acid was obtained from Millipore Sigma. The standard temperature of pivalic acid in etch condition XV was 50° C. The standard temperature of pivalic acid in etch conditions XVI-XVII was 60° C. In each experiment, the pedestal was heated to 25° C. above the intended sample temperature to account for temperature gradients in the carrier wafer. Throughout the process, argon purge flows of 140 sccm, 140 sccm, and 200 sccm were run continuously to protect sensitive internal parts in the chamber.

[0167] Example 19: Copper ALE under standard conditions In this example, ALE was performed under etching condition XV, with the process chamber pedestal heater set at 225° C. (corresponding to an expected sample temperature of 200° C.) and the process chamber lid heater set at 130° C., over 100 cycles, each cycle including a single dose of pivalic acid (preheated to 50° C.) as follows: (a) a 5 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 2.0 Torr; and (b) Purge with approximately 1000-1500 sccm of argon for approximately 75 seconds.

[0168] The RMS roughness of the copper sample before etching was 1.3 nm (roughness) as measured by AFM. Pinholes were detectable on the copper sample before etching, but no tall islands of crystalline copper were detectable. The typical resistivity of the test substrate surface was 3.3 μΩ.cm before etching.

[0169] After 100 cycles, 3-7 Å of copper was etched and the film resistivity was 3.6 μΩ.cm after etching.

[0170] Example 20: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVI with the process chamber pedestal heater set at 165° C., 245° C. or 325° C. (corresponding to potential sample temperatures of 140° C., 220° C. or 300° C.) and the process chamber lid heater set at 130° C. for 200 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and a single dose of water co-flowing with oxygen, as follows: (a) 2-s exposure to water vapor, HO (supplied by vapor draw while maintained at room temperature (25 °C) and assisted by 100 sccm Ar flow through a line to dose HO and 200 sccm Ar flow through a manifold to deliver HO to the chamber) and oxygen, O (supplied at 800 sccm); chamber pressure was maintained at 2.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 5 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 2.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0171] The RMS roughness of the copper sample before etching was 1.3 nm (roughness) as measured by AFM. Pinholes were detectable on the copper sample before etching, but no tall islands of crystalline copper were detectable. The typical resistivity of the test substrate surface was 3.3 μΩ.cm before etching.

[0172] After 200 cycles with the process chamber pedestal set at 165 °C (corresponding to an expected sample temperature of 140 °C), 10-14 Å of copper was etched and the film resistivity was 3.6 μΩ.cm after etching. Pinholes were detectable, but tall islands of crystalline copper were not. The roughness of the copper film after etching was 1.5 nm.

[0173] After 200 cycles with the process chamber pedestal heater set at 245 °C (corresponding to an expected sample temperature of 220 °C), 95-99 Å of copper was etched and the film resistivity was 5.1 μΩ.cm after etching. Pinholes were detectable and some tall islands of crystalline copper were detectable. The copper film roughness after etching was 10.6 nm.

[0174] After 200 cycles with the process chamber pedestal heater set at 325 °C (corresponding to an expected sample temperature of 300 °C), 202-206 Å of copper was etched and the film resistivity was 198 μΩ.cm after etching. Tall islands of crystalline copper were the predominant features. The roughness of the copper film after etching was 48.2 nm.

[0175] Example 21: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVI with the process chamber pedestal heater set at 195° C. (corresponding to an expected sample temperature of 170° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and a single dose of water co-flowing with oxygen, as follows: (a) Exposure to water vapor, HO (supplied by vapor draw while maintaining room temperature (25 °C)) and oxygen, O (supplied at 0, 200, 400, 600, or 800 sccm) for 2 s; chamber pressure was maintained at 2.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 5 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 2.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0176] The RMS roughness of the copper sample before etching was 1.3 nm (roughness) as measured by AFM. Pinholes were detectable on the copper sample before etching, but no tall islands of crystalline copper were detectable. The typical resistivity of the test substrate surface was 3.3 μΩ.cm before etching.

[0177] After 100 cycles with 0 sccm O2 co-flow, 8-12 Å of copper was etched and the film resistivity was 3.6 μΩ.cm after etching.

[0178] After 100 cycles with 200 sccm O2 co-flow, 8-12 Å of copper was etched and the film resistivity was 3.7 μΩ.cm after etching.

[0179] After 100 cycles with 400 sccm O2 co-flow, 11-15 Å of copper was etched and the film resistivity was 3.6 μΩ.cm after etching.

[0180] After 100 cycles with 800 sccm O2 co-flow, 12-16 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes were detectable but tall islands of crystalline copper were not. The roughness of the copper film after etching was 1.6 nm.

[0181] Example 22: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVII with the process chamber pedestal heater set at 195° C. (corresponding to an expected sample temperature of 170° C.) and the process chamber lid heater set at 130° C. over 100 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and one, two or three doses of water in co-flow with oxygen, as follows: (a) Single, two, or three consecutive 2-s exposures to oxygen O (delivered at 800 sccm) administered simultaneously with or without water vapor HO (delivered by a vapor draw while maintained at room temperature (25 °C); where each successive administration was separated by a 5-s purge with 800 sccm argon and the chamber pressure was maintained at 2.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 5 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 2.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0182] The RMS roughness of the copper sample before etching was 1.3 nm (roughness) as measured by AFM. Pinholes were detectable on the copper sample before etching, but no tall islands of crystalline copper were detectable. The typical resistivity of the test substrate surface was 3.3 μΩ.cm before etching.

[0183] After 100 cycles with a single dose of 800 sccm O2 per cycle in step (a), 8-12 Å of copper was etched and the film resistivity was 3.7 μΩ.cm after etching.

[0184] After 100 cycles using a single dose of H2O vapor + 800 sccmO2 per cycle in step (a), 12-16 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes could be detected, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 1.6 nm.

[0185] After 100 cycles using two doses of H2O vapor + 800 sccm O2 per cycle in step (a), 13-17 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching.

[0186] After 100 cycles using three doses of H2O vapor + 800 sccm O2 per cycle in step (a), 13-17 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching.

[0187] Example 23: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVI with the process chamber pedestal heater set at 195° C. (corresponding to an expected sample temperature of 170° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and a single dose of water co-flowing with 800 sccm of oxygen, as follows: (a) Exposure to water vapor, HO (supplied by vapor draw while maintaining room temperature (25 °C)) and oxygen, O (supplied at 800 sccm), for 2 s; chamber pressure was maintained at 1.0, 2.0, or 4.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 5 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 1.0, 2.0 or 4.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0188] The RMS roughness of the copper sample before etching was 1.3 nm (roughness) as measured by AFM. Pinholes were detectable on the copper sample before etching, but no tall islands of crystalline copper were detectable. The typical resistivity of the test substrate surface was 3.3 μΩ.cm before etching.

[0189] After 100 cycles with the chamber pressure maintained at 1.0 Torr during the H2O+O2 and pivalic acid doses, 11-15 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes were detectable and some scattered grains with widths of approximately 40-50 nm were detectable. No tall islands of copper were detectable. The copper film roughness after etching was 1.3 nm.

[0190] After 100 cycles with the chamber pressure maintained at 2.0 Torr during the H2O+O2 and pivalic acid doses, 12-16 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes were detectable, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 1.6 nm.

[0191] After 100 cycles with the chamber pressure maintained at 4.0 Torr during the H2O+O2 and pivalic acid doses, 7-11 Å of copper was etched and the film resistivity was 3.7 μΩ.cm after etching. Pinholes were detectable, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 1.9 nm.

[0192] Example 24: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVII with the process chamber pedestal heater set at 195° C. (corresponding to an expected sample temperature of 170° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and two doses of water in co-flow with oxygen, as follows: (a) Two successive 2-s exposures to oxygen O (delivered at 800 sccm) administered simultaneously with water vapor HO (delivered by a vapor draw while maintained at room temperature (25 °C); each successive administration was separated by a 5-s purge with 800 sccm argon, and the chamber pressure was maintained at 2.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas) for 2 seconds, 4 seconds, 6 seconds, 8 seconds, or 10 seconds; chamber pressure was maintained at 2.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0193] In this example, prior to etching, the copper film was thinned by chemical mechanical planarization from its original as-received thickness of about 500 Å to a thickness of about 400°C. The RMS roughness of the copper sample prior to the etching process was 0.7 nm (roughness) as measured by AFM. Prior to etching, pinholes were detectable and some scattered grains with widths of approximately 40 nm were detectable. No tall islands of copper were detectable prior to etching. Typical resistivity of the test substrate surface prior to etching was 3.4-3.5 μΩ.cm.

[0194] After 100 cycles with a 2 second pivalic acid dose, 5-9 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes were detectable and some scattered small grains of approximately 40-80 nm were detectable. No tall copper islands were detectable. The roughness of the copper film after etching was 1.0 nm.

[0195] After 100 cycles with a 4 second pivalic acid dose, 7-11 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching. Pinholes were detectable and some scattered grains with widths of approximately 40-50 nm were detectable. No tall copper islands were detectable. The roughness of the copper film after etching was 1.2 nm.

[0196] After 100 cycles with a 6 second pivalic acid dose, 14-18 Å of copper was etched and the film resistivity was 3.4 μΩ.cm after etching. Pinholes and long pits could be detected, as well as some scattered grains with a width of approximately 40 nm. No tall islands of copper were detected. The roughness of the copper film after etching was 1.3 nm.

[0197] After 100 cycles with an 8 second dose of pivalic acid, 16-20 Å of copper was etched.

[0198] After 100 cycles with a 10 second dose of pivalic acid, 16-20 Å of copper was etched and the film resistivity was 3.5 μΩ.cm after etching.

[0199] Example 25: Copper ALE under standard conditions In this example, ALE was performed under etching condition XVIII with the process chamber pedestal heater set at 165° C., 195° C. or 225° C. (corresponding to potential sample temperatures of 140° C., 170° C. or 200° C.) and the process chamber lid heater set at 130° C. for 200 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and three doses of hydrogen peroxide as follows: (a) Three successive 2-second exposures to hydrogen peroxide, H2O2 (delivered by a Vaber Draw while maintained at room temperature (25 °C)); where each successive dose was separated by a 5-second purge with 800 sccm argon and the chamber pressure was maintained at 1.0 Torr; (b) purge with 1500 sccm argon for 30 s; (c) an 8 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 1.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0200] The RMS roughness of the copper sample before etching was approximately 0.7 nm (roughness) as measured by AFM. Pinholes could be detected on the copper sample before etching, but no tall islands of crystalline copper could be detected. The typical resistivity of the test substrate surface was 3.7 μΩ.cm before etching.

[0201] After 200 cycles with the process chamber pedestal heater set at 165 °C (corresponding to an expected sample temperature of 140 °C), 4-8 Å of copper was etched and the film resistivity was 3.8 μΩ.cm after etching. Pinholes and small islands were detectable. The roughness of the copper film after etching was 1.8 nm.

[0202] After 200 cycles with the process chamber pedestal heater set at 195 °C (corresponding to an expected sample temperature of 170 °C), 10-14 Å of copper was etched and the film resistivity was 3.8 μΩ.cm after etching. Pinholes were detectable and copper grain coarsening was detectable. The copper film roughness after etching was 2.4 nm.

[0203] After 200 cycles with the process chamber pedestal heater set at 225 °C (corresponding to an expected sample temperature of 200 °C), 13-17 Å of copper was etched and the film resistivity was 4.9 μΩ.cm after etching.

[0204] Example 26: Cobalt ALE under standard conditions In this example, ALE was performed under etching condition XVIII with the process chamber pedestal heater set at 375° C. (corresponding to an expected sample temperature of 350° C.) and the process chamber lid heater set at 130° C. for 180 cycles, each cycle including a single dose of pivalic acid (preheated to 60° C.) and three doses of hydrogen peroxide as follows: (a) Three successive 5-second exposures to hydrogen peroxide, H2O2 (delivered by a Vaber Draw while maintained at room temperature (25 °C)); where each successive dose was separated by a 2-second purge with 800 sccm argon and the chamber pressure was maintained at 1.0 Torr; (b) purge with 1500 sccm argon for 30 s; (c) a 16 second exposure to pivalic acid (CH3)3C-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 1.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0205] The RMS roughness of the exemplary cobalt sample before etching was 0.5 nm as measured by AFM. The cobalt sample before etching had a detectable granular surface, but no tall islands of crystalline cobalt.

[0206] The thickness of the cobalt on this sample before etching was 190 .ANG.. The resistivity of the test substrate surface before etching was 24.8 .mu.Ω.cm.

[0207] After 200 cycles, 8-12 Å of cobalt was etched and the film resistivity was 12.8 μΩ.cm after etching. Pinholes could be detected, but tall islands of crystalline cobalt were not. The roughness of the cobalt film after etching was 0.9 nm.

[0208] Example 27: Copper ALE under standard conditions In this example, ALE was performed under etching condition XIX with the process chamber pedestal heater set at 165° C. (corresponding to an expected sample temperature of 140° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of isobutyric acid (preheated to 50° C.) and two or four doses of oxygen gas, as follows: (a) Two or four successive 2-second exposures to oxygen O2; where each successive dose was separated by a 5-second purge with 800 sccm argon and the chamber pressure was maintained at 4.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 30 second exposure to isobutyric acid (CH3)2CH-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 4.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0209] The RMS roughness of the copper sample before etching was 0.7 nm (roughness) as measured by AFM. Pinholes could be detected on the copper sample before etching, but no tall islands of crystalline copper could be detected. The typical resistivity of the test substrate surface was 3.7 μΩ.cm before etching.

[0210] After 100 cycles with two doses of oxygen per cycle, 104-108 Å of copper was etched and the film resistivity was 5.2 μΩ.cm after etching.

[0211] After 100 cycles with four doses of oxygen per cycle, 89-93 Å of copper was etched and the film resistivity was 5.6 μΩ.cm after etching.

[0212] Example 28: Copper ALE under standard conditions In this example, ALE was performed under etching condition XX, with the process chamber pedestal heater set at 165° C. (corresponding to an expected sample temperature of 140° C.) and the process chamber lid heater set at 130° C., over 100 cycles, each cycle including a single dose of isobutyric acid (preheated to 50° C.) and four doses of water co-flowing with oxygen, as follows: (a) Four successive 2-s exposures to oxygen O (delivered at 800 sccm) administered simultaneously with water vapor HO (delivered by a vapor draw while maintained at room temperature (25 °C); each successive administration was separated by a 5-s purge with 800 sccm argon, and the chamber pressure was maintained at 4.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) exposure to isobutyric acid (CH3)2CH-COOH (supplied with 100 sccm of argon as a carrier gas) for 8, 20 or 30 seconds; chamber pressure was maintained at 4.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0213] The RMS roughness of the copper sample before etching was 0.7 nm (roughness) as measured by AFM. Pinholes could be detected on the copper sample before etching, but no tall islands of crystalline copper could be detected. The typical resistivity of the test substrate surface was 3.7 μΩ.cm before etching.

[0214] After 100 cycles with an 8 second isobutyric acid dose, 13-17 Å of copper was etched and the film resistivity was 4.1 μΩ.cm after etching.

[0215] After 100 cycles with a 20 second isobutyric acid dose, 46-50 Å of copper was etched and the film resistivity was 4.8 μΩ.cm after etching. Pinholes could be detected, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 1.4 nm.

[0216] After 100 cycles with a 30 second dose of isobutyric acid, 75-79 Å of copper was etched and the film resistivity was 5.8 μΩ.cm after etching.

[0217] Example 29: Copper ALE under standard conditions In this example, ALE was performed under etching condition XXI with the process chamber pedestal heater set at 165° C. (corresponding to an expected sample temperature of 140° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of propionic acid (preheated to 40° C.) and two or four doses of oxygen gas as follows: (a) Two or four successive 2-second exposures to oxygen O2; where each successive dose was separated by a 5-second purge with 800 sccm argon and the chamber pressure was maintained at 4.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) a 30 second exposure to propionic acid, CH3CH2-COOH (supplied with 100 sccm of argon as a carrier gas); the chamber pressure was maintained at 4.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0218] The RMS roughness of the copper sample before etching was 0.7 nm (roughness) as measured by AFM. Pinholes could be detected on the copper sample before etching, but no tall islands of crystalline copper could be detected. The typical resistivity of the test substrate surface was 3.7 μΩ.cm before etching.

[0219] After 100 cycles using two doses of oxygen per cycle, 15-19 Å of copper was etched and the film resistivity was 5.4 μΩ.cm after etching.

[0220] After 100 cycles with four doses of oxygen per cycle, 124-128 Å of copper was etched and the film resistivity was 7.2 μΩ.cm after etching.

[0221] Example 30: Copper ALE under standard conditions In this example, ALE was performed under etching condition XXII with the process chamber pedestal heater set at 165° C. (corresponding to an expected sample temperature of 140° C.) and the process chamber lid heater set at 130° C. for 100 cycles, each cycle including a single dose of propionic acid (preheated to 40° C.) and two doses of water co-flowing with oxygen, as follows: (a) Two successive 2-s exposures to oxygen O (delivered at 800 sccm) administered simultaneously with water vapor HO (delivered by a vapor draw while maintained at room temperature (25 °C); each successive administration was separated by a 5-s purge with 800 sccm argon, and the chamber pressure was maintained at 4.0 Torr; (b) purge with 1500 sccm argon for 10 s; (c) exposure to propionic acid, CH3CH2-COOH (supplied with 100 sccm of argon as a carrier gas) for 4 seconds, 12 seconds, 20 seconds, or 30 seconds; chamber pressure was maintained at 4.0 Torr; and (d) Purge with 1500 sccm argon for 60 s.

[0222] The RMS roughness of the copper sample before etching was 0.7 nm (roughness) as measured by AFM. Pinholes could be detected on the copper sample before etching, but no tall islands of crystalline copper could be detected. The typical resistivity of the test substrate surface was 3.7 μΩ.cm before etching.

[0223] After 100 cycles with a 4 second propionic acid dose, 15-19 Å of copper was etched and the film resistivity was 4.1 μΩ.cm after etching. Pinholes could be detected, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 1.4 nm.

[0224] After 100 cycles with a 12 second propionic acid dose, 44-48 Å of copper was etched and the film resistivity was 4.8 μΩ.cm after etching. Pinholes could be detected, but no tall islands of crystalline copper were detectable. The roughness of the copper film after etching was 2.1 nm.

[0225] After 100 cycles with a 20 second propionic acid dose, 67-71 Å of copper was etched and the film resistivity was 5.6 μΩ.cm after etching.

[0226] After 100 cycles with a 30 second propionic acid dose, 81-85 Å of copper was etched and the film resistivity was 5.4 μΩ.cm after etching. [Effects of the invention]

[0227] It has been demonstrated that metals such as Cu, Co, Mo, and W can be etched at temperatures ranging from about 100° C. to less than 400° C. Halogen-free organic acids alone may cause some etching, but it may be limited. This may be due to the removal of the native oxide layer on the metal surface.

[0228] Etching of copper at temperatures below 200°C is demonstrated by cycling with pivalic, isobutyric or propionic acid as oxidizing agents. The oxidizing agent can be water, oxygen, water in parallel with oxygen, or different oxidizing and hydroxylating agents, such as hydrogen peroxide. The oxidizing agent can be selected to improve the etching behavior, for example to improve the etch selectivity. After etching, the films are only slightly rougher than before etching, and the film resistivity is similar to that before etching.

[0229] Pivalic, isobutyric or propionic acid cycled with water, oxygen, water in co-flow with oxygen, or hydrogen peroxide has been demonstrated as an effective gas phase etching process for metals without the use of halogens or halogenated chemicals.

[0230] While the disclosed and claimed invention has been described and illustrated with a certain degree of detail, it will be apparent that this disclosure is made by way of example only, and that those skilled in the art may resort to numerous variations in the conditions and sequence of steps without departing from the spirit and scope of the disclosed and claimed invention.

Claims

1. 1. A thermal atomic layer etching method for selectively etching a metal substrate, carried out in a reactor, comprising the steps of: Step 1, which includes sequentially performing Step 1A and Step 1B: Step 1A, comprising exposing the metal surface to an oxidizing vapor comprising one or more of water vapor, oxygen, ozone, nitrous oxide, nitric oxide, hydrogen peroxide, oxygen plasma, and combinations thereof; and Step 1B, comprising purging the oxidizing vapor with an inert gas; and Step 2, which includes sequentially performing Step 2A and Step 2B: Step 2A, which comprises exposing the metal surface to one or more halogen-free organic acid vaporizers; and Step 2B, which includes purging the one or more halogen-free organic acid vaporizers with an inert gas; One cycle of the method comprises the reaction of the reaction product of the formula (Step 1): ｎ + (Step 2) ｍ wherein n and m are each independently 1 to 20.

2. 10. The method of claim 1 comprising from about 20 to about 2200 cycles.

3. The method of claim 1 , comprising selectively etching one or more of copper, cobalt, molybdenum, and tungsten.

4. Nickel, platinum, ruthenium, zirconium oxide and SiO ２ 10. The method of claim 1, further comprising selectively etching copper in preference to one or more of:

5. Nickel, platinum, ruthenium, zirconium oxide and SiO ２ 10. The method of claim 1, further comprising selectively etching cobalt in preference to one or more of:

6. Nickel, platinum, ruthenium, zirconium oxide and SiO ２ 10. The method of claim 1, further comprising selectively etching molybdenum in preference to one or more of:

7. Nickel, platinum, ruthenium, zirconium oxide and SiO ２ 10. The method of claim 1, further comprising selectively etching tungsten in preference to one or more of:

8. 10. The method of claim 1, wherein the reaction chamber comprises an external heater heated to a temperature of from about 100°C to about 300°C and an internal heater heated to a temperature of from about 100°C to about 350°C.

9. 10. The method of claim 1, wherein the Step 1A oxidizing vapor comprises one or more of water vapor, oxygen, ozone, and hydrogen peroxide.

10. 10. The method of claim 1, wherein the Step 1A oxidizing vapor comprises water vapor and one or more of oxygen and ozone.

11. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizing agents of Step 2A include one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, cyclopropanecarboxylic acid, pentanoic acid, (2E)-but-2-enoic acid, (Z)-2-butenoic acid, and combinations thereof.

12. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizing agents of Step 2A include one or more of propionic acid, isobutyric acid, pivalic acid, and combinations thereof.

13. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizers of Step 2A include propionic acid.

14. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizing agents of Step 2A include isobutyric acid.

15. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizing agents of Step 2A include pivalic acid.

16. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizers of Step 2A include two or more of propionic acid, isobutyric acid, and pivalic acid.

17. 10. The method of claim 1, wherein the one or more halogen-free organic acid vaporizers of step 2A are heated and maintained at about 50°C to about 100°C.

18. 18. A metal-containing film etched by the method of any one of claims 1-17, wherein the metal-containing film comprises topographical features having an aspect ratio of from about 1 to about 50.

19. 18. A metal-containing film etched by the method of any one of claims 1 to 17, wherein the metal-containing film has a resistivity between about 1 μΩ.cm and about 250 μΩ.cm.

20. A metal-containing film etched by the method of any one of claims 1 to 17, wherein the metal comprises one or more of copper, cobalt, molybdenum, and tungsten.

21. 1. Use of one or more of propionic acid, isobutyric acid, pivalic acid, acetic acid, butanoic acid, acrylic acid, methacrylic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 3-butenoic acid, cyclopropanecarboxylic acid, pentanoic acid, (2E)-but-2-enoic acid, (Z)-2-butenoic acid, and combinations thereof as a halogen-free organic vaporizer in combination with one or more of water vapor, oxygen, ozone, nitrous oxide, hydrogen peroxide, and oxygen plasma, and combinations thereof, as an oxidizing vapor, in selective thermal atomic layer etching of a metal substrate comprising one or more of copper, cobalt, molybdenum, and tungsten.

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