Thermal atomic layer etching processes

Abstract

To provide thermal atomic layer etching processes using sequential reactions.SOLUTION: A method of etching a film on a surface of a substrate in a reaction chamber by chemical atomic layer etching comprises at least one etch cycle in which the substrate is alternately and sequentially exposed to a first vapor phase halide reactant and a second vapor halide reactant. The first vapor phase halide reactant may comprise an organic halide compound. During the thermal atomic layer etching (ALE) cycle, the substrate is not contacted with a plasma reactant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 432,318, filed on December 9, 2016; U.S. Provisional Patent Application No. 62 / 449,945, filed on January 24, 2017; U.S. Provisional Patent Application No. 62 / 455,989, filed on February 7, 2017; and U.S. Provisional Patent Application No. 62 / 485,330, filed on April 13, 2017.

Background Art

[0002] Background of the Invention This application relates to an etching process, and more particularly, to a thermal atomic layer etching process using sequential reactions.

[0003] Deposition processes such as atomic layer deposition (ALD) are well known. The ALD process typically utilizes alternating and sequential pulses of gaseous reactants to deposit up to a single layer of material in a controlled and highly conformal manner. Thin films deposited by ALD are used in a wide variety of applications such as the formation of integrated circuits. The controlled removal of materials is also highly desirable. In contrast to ALD, atomic layer etching (ALE) utilizes sequential pulses of gaseous reactants to remove material from a substrate within each reaction cycle. A typical ALE process uses a first reactant to form a first species on the substrate surface that is then removed by a second excited species generated from a plasma.

Summary of the Invention

[0004] In some embodiments, a film on a substrate is etched in a reaction chamber by a chemical atomic layer etching process that includes one or more etch cycles. Each etch cycle includes exposing the substrate to a first gas-phase halide reactant, such as a non-metal halide reactant, to form an adsorbed species on the substrate surface, and subsequently exposing the substrate to a second gas-phase reactant, where the second gas-phase reactant converts the adsorbed species to a volatile species that includes one or more atoms from the surface being etched. In this way, at least some of the material is removed from the film in each etch cycle.

[0005] In some embodiments, the first gas-phase halide reactant, such as a non-metal halide reactant, includes a first halide ligand, and the second gas-phase reactant includes a second halide ligand. In some embodiments, during the etch cycle, the substrate does not contact a plasma reactant. In some embodiments, the etch cycle is repeated two or more times. In some embodiments, the first gas-phase halide reactant may include a metal.

[0006] In some embodiments, the volatile adduct includes an atrane compound. In some embodiments, the atrane compound is formed from tris(2-aminoethyl)amine or triethanolamine.

[0007] In some embodiments, the film includes at least one of W, TiN, TiO2, TaN, SiN, SiO X 、AlO x 、AlO2, Al2O3, ZrO x 、ZrO2, WO3, SiOCN, SiOC, SiCN, AlN, and HfO2.

[0008] In some embodiments, the surface being etched includes a metal nitride, such as TiN or TaN, and the second gas-phase reactant includes a Lewis acid. In some embodiments, the first gas-phase halide reactant comprises a metal halide. In some embodiments, the metal comprises Nb, Ta, Mo, Sn, V, Re, W, or a Group 5 or 6 transition metal. In some embodiments, the first gas-phase halide reactant comprises Sb or Te. In some embodiments, the halide comprises chloride, fluoride, bromide, or iodide. In some embodiments, the first gas-phase halide reactant comprises NbF5.

[0009] In some embodiments, the first gas-phase halide reactant does not contain a metal. In some embodiments, the first gas-phase halide reactant comprises an organic halide compound. In some embodiments, the first gas-phase halide reactant comprises an alkyl halide, an acyl halide, a sulfonyl halide, a sulfenyl halide, a selenyl halide, or a boron halide containing an organic ligand.

[0010] In some embodiments, the first gas-phase halide reactant comprises fluorosulfonic acid, trifluoromethanesulfonic acid, trifluoromethyl trifluoromethanesulfonate, or 1-chloro 2-(pentafluorosulfanyloxy)ethane.

[0011] In some embodiments, the first gas-phase reactant comprises chlorosulfonyl isocyanate or N,N-dimethylsulfamoyl chloride.

[0012] In some embodiments, the first gas-phase reactant comprises boron, hydrogen, and a halide. In some embodiments, the second gas-phase halide reactant comprises phosphorus, oxygen, and a halide. In some embodiments, the first gas-phase halide reactant comprises antimony and a halide.

[0013] In some embodiments, the first gas-phase halide reactant comprises one or more CF3 groups.

[0014] In some embodiments, the first gas-phase halide reactant may include cyclic compounds such as cyclohexadiene (chd), cyclopentadiene. In some embodiments, the first reactant may include α,β-unsaturated carbonyl compounds, such as enones like methyl vinyl ketone.

[0015] In some embodiments, the second gas-phase reactant includes a Lewis base. In some embodiments, the Lewis base includes azines such as pyridine, tetrahydrofuran (thf), DMSO, tetrahydro-thiophene, pyrrole, imidazole, thiazine, or pyrazine. In some embodiments, the second gas-phase reactant includes diamine or dithione. In some embodiments, the second gas-phase reactant includes a heterocyclic reactive compound. In some embodiments, the heterocyclic compound includes thiocarbonate, thiadiazole, or dioxane.

[0016] In some embodiments, the second gas-phase reactant includes planar compounds such as BCl3, BF3, or AlCl3. In some embodiments, the second gas-phase reactant includes a halide. In some embodiments, the second gas-phase reactant includes three or more halides.

[0017] In some embodiments, the second gas-phase reactant includes alkyl isothiocyanates such as SO3, CH3NCS, chloronitrile, COS, or CS2.

[0018] In some embodiments, the second gas-phase reactant has the ability to form a coordination bond to metal atoms adsorbed on the substrate surface.

[0019] In some embodiments, the second gas-phase reactant does not contain metal. In some embodiments, the second gas-phase halide reactant is a carbon-based halide. In some embodiments, the carbon-based halide includes CCl4 or CBr4.

[0020] In some embodiments, an etching cycle includes exposing a substrate to a first gas-phase reactant and then exposing the substrate to a second gas-phase reactant, and the substrate does not contact a plasma reactant during the etching cycle. In some embodiments, the first gas-phase reactant includes CSe2. In some embodiments, the first gas-phase reactant includes a compound having an S=R=S structure, where R can be carbon or any hydrocarbon such as C2-C8. In some embodiments, the first gas-phase reactant includes CS2. In some embodiments, CS2 is involved in the in-situ formation of an etchant. In some embodiments, the second gas-phase reactant includes TEA or TMA.

[0021] In some embodiments, a process of etching a thin film on a substrate in a reaction chamber includes sequentially exposing the substrate to a gas-phase halide reactant, where the gas-phase halide reactant is not an alkyl halide containing hydrogen and the process is not self-regulated.

[0022] In some embodiments, the temperature of the substrate during the etching cycle is 300-500 °C.

[0023] In some embodiments, a method for etching a film on a substrate surface includes exposing the substrate surface to a first gas-phase halide reactant containing a first halide ligand to form a first reactant species on the substrate surface, where the first gas-phase halide reactant does not contain hydrogen. Then, the substrate can be exposed to a second gas-phase halide reactant containing a second halide ligand such that the second gas-phase halide reactant converts the first reactant species to a gas-phase reaction product, where the second gas-phase halide reactant does not contain hydrogen. In some embodiments, the formation of the first reactant species and / or the conversion of the second gas-phase halide reactant to a gas-phase reaction product is not self-regulated. In some embodiments, during the etching cycle, the substrate is not exposed to a plasma reactant. In some embodiments, in one or more etching cycles, the substrate is exposed to a third gas-phase reactant different from the first and second gas-phase reactants.

Brief Description of the Drawings

[0024]

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DETAILED DESCRIPTION OF THE INVENTION

[0025] One or more atomic layer etching (ALE) cycles including a saturation self-limiting adsorption step are provided, in which the substrate surface in the reaction space is alternately contacted with first and second gas-phase reactants to remove one or more sub-layers of material from the substrate. In some embodiments of the ALE type process, one or more etching cycles are provided that include a saturation self-limiting adsorption step in which the substrate contacts a first gas-phase reactant and then, in a second exposure step, the substrate contacts a second gas-phase reactant. In the first adsorption step, the first reactant typically self-limitingly adsorbs onto the material to be etched on the substrate surface. The second exposure step then leads to the formation of volatile by-products including adsorbed atoms, atoms of the second reactant, and some atoms from the etched surface. In this way, the etching of the desired material on the substrate surface can be carefully controlled. In some embodiments, the second reactant forms a volatile adduct that includes atoms from the surface being etched.

[0026] The adduct is considered, for example, as chemical species AB, and is formed by the direct combination of two separate chemical or molecular entities A and B in such a way that each chemical or molecular entity changes in the way of chemical or molecular entity bonding, but there is no loss of atoms within the chemical entities A and B.

[0027] In some embodiments, surface contamination, such as B or C contamination, may be removed from the substrate surface. In this context, the contamination can be, for example, any undesirable atoms on the surface or film such as metal contaminants, S, O, etc. In some embodiments, during the deposition process, contamination can be removed from the substrate surface or from the film itself by an additional selective etching step added to each nth cycle of the deposition cycle.

[0028] In some embodiments, the target material to be etched includes metals such as Ti, Ta, Al, Zr or Hf, W. In some embodiments, the material to be etched is X W, TiN, TiO2, TaN, SiN, SiO x , AlO x , AlO2, Al2O3, ZrO x , ZrO2, WO3, AlN, HfO x , and includes one or more of HfO2. In some embodiments, the material to be etched includes a metal nitride or a metal oxide or a mixture thereof. In some embodiments, the material to be etched includes Si, Ge, a-C, graphene, polymer, SiO

[0029] In some embodiments, the gas-phase reaction is avoided by alternately and sequentially supplying reactants into the reaction chamber. The gas-phase reactants are separated from each other within the reaction chamber. In some embodiments, this can be achieved, for example, by removing excess reactants and / or reaction by-products from the reaction chamber between reactant pulses. In some embodiments, the reactants may be removed from proximity to the substrate surface with the aid of a purge gas and / or a vacuum. In some embodiments, excess reactants and / or reactant by-products are removed from the reaction space by purging, for example, with an inert gas. In some embodiments, purging includes exposing the substrate surface to a purge gas such as an inert gas. Due to the separation of reactants and the self-regulating nature of the reaction, materials smaller than a single layer of material are generally removed in each ALE etch cycle. However, in some embodiments, multiple monolayers may be removed in each cycle. In some embodiments, the reaction may be neither self-regulating nor saturated. In some embodiments, at least one of the steps, such as exposure to a first gas-phase reactant, a second gas-phase reactant, or reactants in an additional phase, the reaction, such as an etching reaction, is neither self-regulating nor saturated. In some embodiments, the reactant pulses may be partially or completely overlapping. For example, in some embodiments, one reactant may flow continuously into the reaction space while one or more additional reactants are provided intermittently at desired intervals.

[0030] The ALE method disclosed herein is a thermal etching process that is the opposite of a plasma etching process. Thus, plasma reactants are not used in the ALE etch cycle. It is called a thermal ALE process to distinguish it from processes that use plasma reactants, but in some embodiments, the ALE reaction may have zero activation energy and thus may not require additional thermal energy. Thus, the reaction may also be referred to herein as a chemical etching process. The thermal ALE method can reduce damage to the underlying substrate and may be more desirable than the plasma ALE method in some situations. The thermal ALE method also takes into account the isotropic etching of the non-direct aiming function.

[0031] The ALE process disclosed herein utilizes certain reactants or combinations of reactants that have been found to enable controlled etching when plasma is not used. In some embodiments, metal halides such as chlorides, fluorides, bromides, and iodides such as iodides of group 5 or 6 transition metal halides, such as metal halides, are used as the first reactant and are contacted with the substrate in a first self-limiting adsorption step. The metal in the first reactant may be, for example, Nb, Ta, Mo, Sn, V, Re, Te, or W. In some embodiments, the metal halide first reactant is NbCl5, SnCl4, TaCl5, MoCl x wherein x is about 3-5, or WCl x wherein x is about 4-6, is a metal chloride. In some embodiments, the metal halide first reactant is a metal fluoride such as NbF5, TaF5, WF6, VF5, ReF6, ReF7, or MoF6. In some embodiments, non-metals or semi-metal fluorides such as TeF6, SbF5 or AsF5 can be used as the first reactant. In some embodiments, the metal halide may be a metal bromide or metal iodide (such as SnBr4, SnI4, etc.).

[0032] In some embodiments, the first reactant may include a halide that is not a metal halide.

[0033] In some embodiments, the first reactant may include an organic halide compound. For example, in some embodiments, the first reactant may include an alkyl halide compound. In some embodiments, the first reactant can include an aromatic, saturated, or unsaturated aliphatic alkyl halide compound containing two or more carbon atoms. In some embodiments, the first reactant may include a substituted alkyl halide. For example, in some embodiments, the first reactant may include tert-butyl chloride, 1,1-dichloroethane, 1,2-dichloroethane, or trichloroethane, trifluoroethanol, trifluorisopropanol. In some embodiments, the first reactant may include an aromatic, saturated, or unsaturated aliphatic alkenyl halide compound. For example, in some embodiments, the first reactant may include a substituted vinyl halide or allyl halide.

[0034] In some embodiments, the first reactant may include an organic oxyhalide. In some embodiments, the first reactant may include a halogenated acyl compound such as an aromatic, saturated, or unsaturated aliphatic halogenated acyl compound, which includes halogenated diacyl and halogenated triacyl. For example, in some embodiments, the first reactant may include fumaryl chloride, malonyl chloride, succinyl, or oxalyl halide. In some embodiments, the first reactant may include terephthaloyl chloride. In some embodiments, the first reactant may include 1,3,5-benzenetricarbonyl trichloride.

[0035] In some embodiments, the first reactant may include a sulfonyl halide such as an aromatic, saturated, or unsaturated aliphatic sulfonyl halide. In some embodiments, the first reactant may include, for example, ethanesulfonyl fluoride (C2H5FO2S), methanesulfonyl chloride (CH3ClO2S), methanesulfonyl fluoride (CH3FO2S), phenylsulfonyl fluoride (PhFO2S), pyridinesulfonyl fluoride (C5H4FNO2S), thiophenesulfonyl fluoride (C4H3FO2S2), cyanomethanesulfonyl chloride (C2H2ClNO2S), chloromethanesulfonyl chloride (ClCH2SO2Cl), or trifluoromethanesulfonyl chloride (CF3SO2Cl). In some embodiments, the first reactant may include a sulfenyl halide compound or a selenenyl halide compound. For example, in some embodiments, the first reactant may include trichloromethanesulfenyl chloride (CCl3SCl), or chlorocarbonylsulfenyl chloride (ClCOSCl). In some embodiments, the first reactant may include a compound having the formula PhSeCl, where Ph is a phenyl group. In some embodiments, the first reactant may include a compound having the formula RSeX, where R is an alkyl ligand and X is a halide.

[0036] In some embodiments, the first reactant may include sulfur, carbon, and one or more halide atoms, such as thiophosgene (CSCl2).

[0037] In some embodiments, the first reactant may include sulfur, phosphorus, and one or more halide atoms (such as phosphoryl thiochloride (PSCl3) and phosphoryl thiofluoride (PSF3)).

[0038] In some embodiments, the first reactant may include phosphorus and one or more halide atoms.

[0039] In some embodiments, the first reactant may include sulfur, nitrogen, and one or more halide atoms, such as thiazyl chloride, thiazyl fluoride, thiazyl trifluoride (NSF3).

[0040] In some embodiments, the first reactant may include phosphorus, oxygen, and one or more halide atoms (e.g., phosphoryl chloride (POCl3), etc.).

[0041] In some embodiments, the first reactant may include a ligand, phosphorus, oxygen, and one or more halides. In some embodiments, the first reactant may have the general formula ligand - POX2. Exemplary ligands include dialkylamides (e.g., N,N-dimethylphosphoramidic dichloride), phenyl (e.g., phenylphosphoryl dichloride), and alkyl (e.g., tert-butylphosphonyldichloride and methylphosphonyldichloride, etc.).

[0042] In some embodiments, the first reactant may include a ligand, phosphorus, and one or more halides. In some embodiments, the first reactant may have the general formula ligand - PX2, where X is a halide other than chlorine and fluorine only. For example, the first reactant may include dimethylphosphoramide dichloride.

[0043] In some embodiments, the first reactant may include sulfur and carbon. In some embodiments, the first reactant may include an S=R=S structure, where R may be carbon or any hydrocarbon such as C2-C8 hydrocarbon. For example, in some embodiments, the first reactant may include carbon disulfide (CS2) or carbon diselenide (CSe2). In some embodiments, the first reactant may form an adduct using a transition metal incorporated into a substrate.

[0044] In some embodiments, the first reactant may include a compound containing oxygen and sulfur, and a halide group and a hydrogen group, or a hydrocarbon group such as an alkyl group.

[0045] In some embodiments, the first reactant may include a sulfinyl halide such as an aromatic or aliphatic or substituted aromatic or substituted aliphatic, saturated, or unsaturated sulfinyl halide. In some embodiments, the first reactant may include, for example, trichloromethanesulfinyl chloride, trifluoromethanesulfinyl fluoride, trifluoromethanesulfinyl chloride, tert-butylsulfinyl chloride.

[0046] In some embodiments, the first reactant may include a sulfonic acid halide compound such as an aromatic or aliphatic or substituted aromatic or substituted aliphatic, saturated or unsaturated sulfonic acid halide. For example, in some embodiments, the first reactant may include fluorosulfonic acid (FSO3H) and / or trifluoromethanesulfonic acid (CF3SO3H).

[0047] In some embodiments, the first reactant may include a sulfonate compound such as an aromatic or aliphatic or substituted aromatic or substituted aliphatic or saturated, or unsaturated sulfonate halide. For example, in some embodiments, the first reactant may include trimethylsilyl trifluoromethanesulfonate (C4H9F3O3SSi) and trifluoromethyl trifluoromethanesulfonate (CF3SO3CF3).

[0048] In some embodiments, the first reactant can include a substituted sulfur trifluoride having the formula A-SF3, wherein A can be an amino group containing a methylmethanamino in dimethyl sulfide, diethyl sulfide, benzene, alkyl group, pyridine, thiophene, cyclopropane, or trifluoro(N-methylmethanaminato)sulfur.

[0049] In some embodiments, the first reactant may include a sulfuran compound having the formula X-O-SF y wherein X is an alkyl ligand, an aromatic ligand or a halide, and y is from 1 to 5. For example, in some embodiments, the reactant may include 1-chloro 2-(pentafluorosulfanyloxy)ethane (SF5OC2H2Cl).

[0050] In some embodiments, the first reactant may include sulfur, oxygen and halides (such as chlorine or fluorine), and hydrocarbons, and may include a cyclic alkyl group such as a cyclopropyl group, such as cyclopropylthionyl chloride.

[0051] In some embodiments, the first reactant may include a reactant having the general formula ligand-CCl3. In some embodiments, the first reactant may include nitrogen, halides, carbon and oxygen. For example, the reactant may include trichloronitromethane (CCl3NO2), or trichloroacetyl isocyanate (Cl3CCONCO).

[0052] In some embodiments, the first reactant may include hydrogen, halides, carbon and oxygen. In some embodiments, the first reactant may include, for example, alkyl chloroformates such as ethyl chloroformate, methyl chloroformate, propyl chloroformate, chloromethyl chloroformate or 2,2,2-trichloroethoxycarbonyl chloride.

[0053] In some embodiments, the first reactant may include nitrogen, hydrogen, halides, carbon and oxygen. In some embodiments, the first reactant may include, for example, trichloroacetamide or a substituted trichloroacetamide (O-allyl 2,2,2-trichloroacetimidate).

[0054] In some embodiments, the first reactant may include nitrogen, halide, and carbon. In some embodiments, the first reactant may include, for example, trichloroacetonitrile.

[0055] In some embodiments, the first reactant may contain nitrogen, carbon, sulfur, halide, and oxygen.

[0056] In some embodiments, the first reactant may include carbon, sulfur, halide, hydrogen, and oxygen.

[0057] In some embodiments, the first reactant may include nitrogen, carbon, sulfur, halide, hydrogen, and oxygen. In some embodiments, the first reactant may include chlorosulfonyl isocyanate, chloromethyl chlorosulfate, or N,N-dimethylsulfamoyl chloride.

[0058] In some embodiments, the first reactant may contain halogen and succinimide groups. In some embodiments, for example, the first reactant may include N-chlorosuccinimide, N-bromosuccinimide.

[0059] In some embodiments, the first reactant may include boron, halide, and hydrogen. In some embodiments, the first reactant may include boron, fluorine, and hydrogen. In some embodiments, the first reactant may include, for example, HBF4. In some embodiments, HBF4 is used as a composite compound when the first reactant is not vaporized in the reactant source container.

[0060] In some embodiments, the first reactant may include a boron trihalide in a stabilizer, and the stabilizer may be, for example, but not limited to, an alkylamine, an alkyl nitrile, water, or dimethyl sulfide, or any other compound that can form either a volatile complex or an adduct with boron trihalide. In some embodiments, the first reactant may include, for example, a boron trifluoride ethylamine complex.

[0061] In some embodiments, the first reactant is a boron halide of the general formula BX a Y b wherein "a" and "b" can be greater than or equal to zero or be 1 or more, and wherein X and Y can be halides including fluorine, chlorine, bromine, and iodine. The first reactant may be stabilized, for example, in an organic stabilizer containing at least one carbon, oxygen, or hydrogen, including ethanol, diethyl ether, dimethyl ether, dimethyl sulfide.

[0062] In some embodiments, the first reactant may include a diethyl ether complex of tetrafluoroboric acid. In some embodiments, the first reactant may include, for example, a boron trifluoride dihydrate. In some embodiments, the first reactant may include, for example, a boron trifluoride tetrahydrofuran complex.

[0063] In some embodiments, the first reactant flows into the reactor during the etch cycle or periodically and continuously.

[0064] In some embodiments, the first reactant may include halides such as antimony and fluorine. In some embodiments, the first reactant may include antimony, fluorine, and hydrogen. In some embodiments, the first reactant may include antimony, fluorine, oxygen, and nitrogen. In some embodiments, the first reactant may include antimony, fluorine, and oxygen. In some embodiments, the first reactant may include antimony, fluorine, and at least one ligand other than antimony or fluorine. In some embodiments, the first reactant may include a fluoroantimonate compound. For example, in some embodiments, the first reactant may include hexafluoroantimonic acid (HSbF6), nitronium hexafluoroantimonate NO2SbF6, nitrosonium hexafluoroantimonate (NOSbF6), or hexafluoroantimonic acid hydrate (HSbF6·6H2O).

[0065] In some embodiments, the first reactant may include phosphorus and oxygen. In some embodiments, the first reactant may include phosphorus, oxygen, and hydrogen. In some embodiments, the first reactant may include phosphorus, oxygen, and halides such as fluorine. In some embodiments, the first reactant may include phosphorus, oxygen, and a hydrocarbon group (such as an alkyl group). In some embodiments, the first reactant may include a phosphoric acid compound. For example, in some embodiments, the first reactant may include ammonium hexafluorophosphate.

[0066] In some embodiments, the first reactant can include a compound having four or more halides, five or more halides, or six or more halides, and the halides can be, but are not limited to, chlorine and / or fluorine. In some embodiments, the first reactant is a -CF3 group. In some embodiments, the first reactant may include a -CF3 group that can assist in selective etching. In some embodiments, the first reactant may include a -CF3 group and sulfur. In some embodiments, the first reactant may include a -CF3 group, nitrogen, and oxygen. In some embodiments, the first reactant may include a -CF3 group, carbon, hydrogen, and oxygen, such as chlorodifluoroacetic acid. In some embodiments, the first reactant may include a -CF3 group and an -NH2 group. In some embodiments, the first reactant may include a -CF3 group, an -NH2 group, and either oxygen or sulfur.

[0067] In some embodiments, the first reactant includes a -CF3 group, oxygen, and nitrogen and may be connected via a hydrocarbon chain such as an alkyl chain. In some embodiments, the first reactant can include one or more CX a Y b - groups, where X and Y are halides and can be, but are not limited to, fluorine and / or chlorine. In some embodiments, the first reactant may also include carbon, hydrogen, and oxygen, such as chlorodifluoroacetic anhydride. In some embodiments, the first reactant may include HCl or HF, for example, as a stabilizer when the first reactant is not vaporized in the reactant source container. In some embodiments, the first reactant may include HCl, which is supplied separately to the reaction chamber.

[0068] In some embodiments, the first reactant may include carbon and halogen. In some embodiments, the first reactant has the formula CX a Y bmay contain a compound, where a and b can be 1 or more. For example, in some embodiments, the first reactant may include CCl3Br, CCl2Br2. In some embodiments, the first reactant is of the formula CHX a Y b and may contain a compound, where a and b can be 1 or more. For example, in some embodiments, the first reactant may include CHCl2Br, CHCl3, CHCl2Br or CHClBr2.

[0069] In some embodiments, the first reactant may include a compound of the formula MO c X a Y b wherein c may be greater than zero, and a and / or b may be 1 or more and may be zero or more, and M may be any transition metal. For example, in some embodiments, M is rhenium, niobium, tungsten, titanium, vanadium, chromium, X and Y may be different halides from each other, or X and Y may be the same halide. In some embodiments, the first reactant may include compounds of the formula MoOF4, ReOF4, WOF4, ReOF5, ReO2F2, ReO2Cl3, NbOF3.

[0070] In some embodiments, the first reactant may contain a negative element such as a halide such as fluorine or chlorine, and it may be close to the atom to which the reactant binds to the surface. For example, in some embodiments, the first reactant may contain hexafluoroacetylacetone (Hhfac) through which fluorine is close to the C=O group to which hfac binds to the surface.

[0071] In some embodiments, the first reactant is of the general formula X a Y bmay contain a halo-halogen compound having the formula, where X and Y may be chlorine, fluorine, bromine, or iodine, and a and b are stoichiometric coefficients, where each a and b can be 1 or greater. In some embodiments, the first reactant may include ClF, BrCl, ClF3, BrF3, ClF5, BrF5, IF5, IF7, ICl3, ICl5, or ICl. In some embodiments, the first reactant may include halogen and oxygen. In some embodiments, the first reactant has the general formula O b X a or O b X a Y c and may include an oxyhalide. In some embodiments, the first reactant may include multiple halogens and multiple oxygens. In some embodiments, the first reactant may include OF2, FClO2, or FClO3.

[0072] In some embodiments, the first reactant may include halogen, nitrogen, and sulfur. In some embodiments, the first reactant may include, for example, thiazyl chloride (NSCl). In some embodiments, the first reactant may include halogen, nitrogen, oxygen, and sulfur. In some embodiments, the first reactant may include, for example, NSOCl.

[0073] In some embodiments, the first reactant may include halogen, phosphorus, and oxygen. In some embodiments, the first reactant may include, for example, POCl3.

[0074] In some embodiments, the first reactant may include a substituted alkyl ammonium hydroxide compound or an alkyl amine compound. In some embodiments, an alkyl ammonium halide or hydroxide compound is formed on the surface. For example, in some embodiments, the first reactant may include, or may be formed on the surface, tetramethylammonium hydroxide, tetramethylamine, or the like on the surface. In some embodiments, the first reactant may include a secondary alkyl amine or a tertiary alkyl amine.

[0075] In some embodiments, the first reactant may include a boron halide compound containing an organic ligand. For example, in some embodiments, the first reactant may include a compound having the formula BX n L 3-n wherein L is an organic ligand such as an acetylacetonato (acac) ligand, X is a halide, and n is 1 or 2. In some embodiments, the first reactant may include BF2acac.

[0076] In some embodiments, the first reactant may include carbon, hydrogen, and / or tin. For example, in some embodiments, the first reactant may consist of hexamethylditin. In some embodiments, the first reactant may include carbon, hydrogen, halide, and tin. For example, in some embodiments, the first reactant may include trimethylstannyl bromide.

[0077] In some embodiments, the first gas-phase reactant includes a first halide ligand, and the second gas-phase reactant includes a second halide ligand. In some embodiments, both the first and second gas-phase reactants include Cl. In some embodiments, the second halide ligand is different from the first halide ligand.

[0078] In some embodiments, the first vapor-phase halide reactant may be inorganic. In some embodiments, the first vapor-phase halide reactant does not contain carbon and does not contain both C and H. In some embodiments, the second vapor-phase reactant may be inorganic. In some embodiments, the second vapor-phase reactant does not contain carbon and may not contain both C and H.

[0079] In some embodiments, the first vapor-phase reactant and the second vapor-phase reactant contain the same number of halide ligands. In some embodiments, the first vapor-phase reactant and the second vapor-phase reactant contain different numbers of halides. In some embodiments, the first vapor-phase reactant contains one, two, three, four, five, or six halides, while the second vapor-phase reactant separately contains one, two, three, four, five, or six halides.

[0080] In some embodiments, both the first and second vapor-phase reactants contain the same halide. In some embodiments, the first and second vapor-phase reactants contain different halides.

[0081] In some embodiments, the first vapor-phase halide reactant contains one, two, three, four, five, or six halides, which may all be the same halide or may be different, and the second vapor-phase reactant contains a different number of halides than the first reactant. The halides of the second reactant may be the same as or different from the halides of the first reactant. In some embodiments, the second vapor-phase reactant may be selected from the reactants described herein. That is, in some embodiments, two (or more) different reactants referred to as the "first vapor-phase reactant" can be used as the first and second reactants in the deposition cycle.

[0082] In some embodiments, the first gas-phase halide reactant contains 2 to 6 halides (or halogen atoms), such as chlorides or fluorides, while the second gas-phase reactant contains 2 to 6 halides (or halogen atoms). In some embodiments, the first gas-phase halide reactant contains 3 to 5 halides (or halogen atoms), such as chlorides or fluorides, while the second gas-phase reactant contains 3 to 5 halides (or halogen atoms). The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0083] In some embodiments, both the first and second gas-phase halide reactants contain 4 to 5 halides (or halogen atoms), such as chlorides or fluorides. The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0084] In some embodiments, the first gas-phase halide reactant is a fluorinating agent or a chlorinating agent, while the second gas-phase reactant is a chlorinating agent or a fluorinating agent. In some embodiments, the first gas-phase halide reactant is a fluorinating agent, while the second gas-phase reactant is a chlorinating agent. In some embodiments, the first gas-phase reactant is a chlorinating agent, while the second gas-phase reactant is a fluorinating agent.

[0085] In some embodiments, the first gas-phase halide reactant contains a plurality of, for example, two or more, three or more, four or more, or five or more halides (or halogen atoms), such as chlorides or fluorides, while the second gas-phase reactant contains less than five, less than four, less than three, or less than two halides (or halogen atoms). The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0086] In some embodiments, the first gas-phase halide reactant contains 4 to 5 halides (or halogen atoms), such as chlorides or fluorides, while the second gas-phase reactant contains less than five, less than four, less than three, or less than two halides (or halogen atoms). The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0087] In some embodiments, the second gas-phase halide reactant contains a plurality of, such as two or more, three or more, four or more, or five or more halides (or halogen atoms), such as chlorides or fluorides, while the first gas-phase reactant contains less than five, less than four, less than three, or less than two halides (or halogen atoms). The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0088] In some embodiments, the second gas-phase halide reactant contains 4 to 5 halides (or halogen atoms), such as chlorides or fluorides, while the first gas-phase reactant contains less than five, less than four, less than three, or less than two halides (or halogen atoms). The halides of the second gas-phase reactant may be the same as or different from the halides of the first gas-phase reactant.

[0089] In some embodiments, the first non-metal halide reactant is a non-metal halide reactant having the formula ligand-SX2, together with ligand-SX3, where X is a halide and S can be sulfur and phosphorus, and the ligand can be a dialkyl ether similar to dimethyl ether, a dialkyl thioether similar to dimethyl thioether, an alkylamine similar to dimethylamine, benzene, alkyl, pyridine, thiophene, cyclopropane, and n-haloiminosulfur, etc. In some embodiments, the first gas-phase non-metal halide reactant can be trifluoro(N-methylmethanamido)sulfur. In some embodiments, the first gas-phase non-metal halide reactant is N-fluoroformyliminosulfur difluoride (SF2=NCOF).

[0090] In some embodiments, a halide reactant such as fluoride, chloride, bromide, or iodide is used as a second reactant that reacts with an adsorbate species to form a volatile reaction product that can be removed from the reaction space. In some embodiments, the second reactant is a non-metal halide or a semi-metal halide. For example, in some embodiments, the second reactant is a carbon-based halide. In some embodiments, the second reactant can include, for example, a carbon-based fluoride, bromide, iodide or chloride, such as CCl4 or CBr4. In some embodiments, the second reactant is a semi-metal-based halide similar to a Ge halide, such as a semi-metal chloride such as SbCl3, SbCl5, SiCl4, or GeCl4. In some embodiments, any of the reactants described above in relation to the first reactant can be used as the second reactant together with any of the first reactants described above. That is, any two of the first reactants described above may be used as the first reactant and the second reactant. For reasons of simplification, carbon-based halides, including CCl4, are considered organic halides or alkyl halides.

[0091] In some embodiments, the second reactant may include a compound having the ability to form a volatile adduct on the surface or substrate that was in contact with the first reactant described herein. The second reactant forms a volatile adduct with a species formed on the substrate surface by the first reactant, and the adduct contains one or more atoms from the surface to be etched. The volatile adduct may then be removed from the reaction space. For example, in some embodiments, the second reactant may include a compound having the ability to form a volatile adduct in addition to a halogenated surface such as a chlorinated high-k surface, in contact with surfaces such as -OH, -SH, -NH2, =NH terminations, or on an oxidized surface, or on an amine-conditioned surface.

[0092] In some embodiments, the second reactant may include a compound capable of forming a compound with a metal halide added on the surface that was in contact with the first reactant as described herein.

[0093] In some embodiments, the second reactant may include a compound having the ability to form a coordination bond to a metal atom adsorbed on the substrate surface. For example, diamine, dithione, thiocarbonate, and thiadiazole can form coordination bonds to metal atoms on the surface.

[0094] In some embodiments, the second reactant may include a Lewis base that will form a volatile adduct in reaction with a metal on the surface to be etched, such as a transition metal. For example, in some embodiments, the second reactant may include pyridine, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), tetrahydrothiophene, or other Lewis bases that can form a volatile adduct on the surface. In some embodiments, the Lewis base includes alkyl or aryl or substituted nitriles (cyanates) and methyl nitrile-like isonitriles, methyl isonitrile, NH3 gas, alkyl or substituted isothiocyanates, isocyanates, polyols (such as propane 1,2,3 triol), ethanolamine, sulfones (such as methylsulfonylmethane), PX3, and trichloronitromethane.

[0095] In some embodiments, when the material being etched includes a metal nitride such as TiN or TaN, the second reactant may include a Lewis acid. In some embodiments, the Lewis acid is SO3. In some embodiments, the second reactant may include planar compounds such as BCl3, BF3, or AlCl3, compounds having a conjugated electron system, or hypervalent molecules that will form an adduct on the surface to be etched.

[0096] In some embodiments, the second reactant can include a diamine compound or a dithione compound that will form an adduct on the surface to be etched.

[0097] In some embodiments, the second reactant may include alkyl or aryl isocyanates, or substituted forms thereof, that can also form an adduct on the surface of the substrate to be etched, such as a surface containing a transition metal. In some embodiments, the second reactant may include alkyl or aryl isothiocyanates, or substituted forms thereof.

[0098] In some embodiments, the volatile adduct-forming second reactant may include an alkyl or aryl polyol such as, for example, 1,2,3, propanetriol and ethanediol.

[0099] In some embodiments, the second reactant that forms the adduct may contain -NH2 and -OH functional groups such as, for example, ethanolamine.

[0100] In some embodiments, the second reactant that forms the adduct may include sulfur trioxide (SO3).

[0101] In some embodiments, the second reactant may include a sulfone such as, for example, methylsulfonylmethane, which can assist in the formation of the volatile adduct.

[0102] In some embodiments, the second reactant may include a heterocyclic reactive compound. In some embodiments, the second reactant may include a heterocyclic reactive compound containing more than one nitrogen atom. In some embodiments, the second reactant may include a heterocyclic reactive compound containing more than one sulfur atom. In some embodiments, the second reactant may include a heterocyclic reactive compound containing more than one oxygen atom. In some embodiments, the second reactant may include a heterocyclic reactive compound containing three or more different atoms such as oxygen, boron, nitrogen, and sulfur atoms. For example, in some embodiments, the second reactant may include a thiocarbonate compound such as ethylene trithiocarbonate or dimethyl trithiocarbonate. In some embodiments, the second reactant may include a thiadiazole compound such as dichlorothiadiazole, for example, 3,4-dichloro-1,2,5-thiadiazole. In some embodiments, the second reactant may include a dioxane compound such as 1,4-dioxane. In some embodiments, the second reactant may include a substituted or unsubstituted unsaturated cyclic compound including cyclohexadiene, cyclopentadiene, such as trans-tris(trimethylsilyl)cyclohexadiene and bis(trimethylsilyl)cyclohexadiene.

[0103] In some embodiments, the second reactant may include a compound having the ability to form an atrane compound when contacting the surface that has been exposed to the first reactant described herein. For example, in some embodiments, the second reactant may form a volatile adduct such as a metal atrane compound when contacting the surface that has been exposed to a first reactant such as a first metal halide reactant as described herein. The second reactant may include TIPA, TIPEA, TMEA, tris(2-aminoethyl)amine, or triethanolamine (TEA).

[0104] In some embodiments, a metal film such as a transition metal film is etched by an ALE process that includes exposing a substrate to a first halide reactant such as a metal halide similar to NbCl5 and a second volatile adduct-forming reactant such as CS2. In some embodiments, CS2 is used on a halogenated surface such as HfCl x , TiCl x , or TiONCl x to form volatile products.

[0105] The substrate surface to be etched is contacted alternately with the first and second reactants to remove volatile adducts and reaction by-products, thereby etching the transition metal film. In one embodiment, TiN can be etched by an ALE process that includes alternately exposing a substrate to a chlorine-containing compound such as NbCl5 and an adduct-forming compound such as CS2.

[0106] In some embodiments, exposure to the first halide reactant halogenates a metal surface such as an Fe, Co, Ni, or Cu surface. The surface then forms a volatile metal adduct and is exposed to a second reactant that etches the surface.

[0107] In some embodiments, a metal oxide film on a substrate is etched by an ALE process that includes an etch cycle in which the metal oxide film is alternately exposed to a first halide reactant such as a metal halide or CCl4 and a second volatile adduct-forming reactant such as CH3CN, NH3, or 1,4-dioxane. In some embodiments, an Al2O3, HfO2, TiO2, or other metal oxide film on a substrate surface is etched by alternate exposure to a first reactant that includes a metal halide or CCl4 and a second reactant that includes 1,4-dioxane.

[0108] In some embodiments, the second reactant (such as CCl4) can be used alone without the first reactant and can provide the desired etching selectivity for the desired controlled etching.

[0109] In some embodiments, the first reactant or the second reactant can be used alone for etching and can provide the desired etching selectivity for the desired controlled etching. Any by-products formed can be removed by purge and / or pumping.

[0110] In some embodiments, only the first reactant can be used in a method of periodically pulsing.

[0111] In some embodiments, a continuous flow of the first reactant with a flow rate change or a "pulsing" of the flow rate is used.

[0112] In some embodiments, the first and second reactants can be used interchangeably for the desired controlled etching with the desired etching selectivity.

[0113] In some embodiments, two or more compounds described herein can be used periodically in an atomic layer etching process as the first reactant. For example, in some embodiments, the first reactant is NbF5 and the second reactant is a fumarate or malonyl or any acyl halide.

[0114] In some embodiments, the first reactant is NbF5 and the second reactant is CCl4.

[0115] In some embodiments, the first reactant and the second reactant contain the same halide ligand. For example, the first reactant may include a metal chloride such as NbCl5, TaCl5, MoCl3 or WCl2. And the second reactant may also contain Cl such as CCl4.

[0116] In some embodiments, either or both of the first and second reactants contain a halide, do not contain hydrogen, or contain a halide but contain neither oxygen nor hydrogen. In some embodiments, either the first or second reactant contains a halide but does not contain hydrogen, or contains a halide but contains neither oxygen nor hydrogen. In some embodiments, at least one of the first and second reactants is not Sn(acac)2. In some embodiments, at least one of the first and second reactants is not TMA. In some embodiments, at least one of the first and second reactants is not HF gas. In some embodiments, at least one of the first and second reactants is not HF-pyridine. In some embodiments, the first and second reactants are not HF and Sn(acac)2. In some embodiments, the first and second reactants are not HF and SiCl4. In some embodiments, H is not used. In some embodiments, TMA is not used. In some embodiments, Sn(acac)2 is not used.

[0117] In some embodiments, one or more additional reactants may be utilized. In some embodiments, one or more reactants may be used to improve or adjust the selective etching. The additional reactants may be provided separately or may be combined with one or more reactants such as the second reactant. In some embodiments, the additional reactant may be an oxygen source. For example, the additional reactant may include, for example, water, oxygen, or ozone.

[0118] In some embodiments, water, oxygen, and / or ozone are combined with the second reactant. The ratio of water, oxygen, or ozone to the second reactant may be varied to adjust the reaction, for example, to adjust the selectivity of the etching process, or further, to stop the etching by forming an etch stop layer.

[0119] In some embodiments, the additional reactant is SO 3、 H2S, NH3, hydrazine, where a and b are greater than zero. In some embodiments, the additional reactant may be used in combination with other first and / or second reactants.

[0120] In some embodiments, the additional reactant may be N2O gas. The additional reactant may be additionally supplied from a separate source.

[0121] In some embodiments, the etch cycle additionally includes a phase in which the substrate is exposed to a ligand exchanger. In some embodiments, the ligand exchanger is selected from Hacac TMA, Sn(acac)2. In some embodiments, the ligand exchanger may consist of adjacent ketone groups such as, for example, hexafluoroacetylacetonato (Hhfac), diacetyl, thd. In some embodiments, the ligand exchanger consists of an M(thd)x compound, where M is a metallic transition metal and an alkaline earth metal, and x is greater than 1 and may in some cases be greater than 2. In some embodiments, the metal "M" may consist of at least one "thd" and / or at least one "acac" or both, such as, for example, Mg(thd)(acac).

[0122] As described above, in some embodiments, the ALE process is preferably a thermal process. Thus, in some embodiments, the plasma reactant is not used as the first or second reactant. In some embodiments, the plasma reactant is not used in the ALE process.

[0123] In some embodiments, for controlled etching, one or more ALE cycles are performed, with each cycle removing material from the desired substrate surface. In some embodiments, in each ALE cycle, up to a single layer of material is removed, and the mass removed per cycle is approximately a single layer of volume, assuming a constant density. In some embodiments, more than a single layer is removed per cycle. Each ALE cycle typically includes at least two distinct steps. Contact with the substrate surface and removal of reactants from the substrate can be considered one step.

[0124] In the first step, a first reactant in the gas phase contacts the substrate surface to be etched. In some embodiments, the first reactant forms up to approximately one monolayer of adsorbed species. In particular, in some embodiments, the first reactant reacts with accessible substrate molecules of the material to be removed on the substrate surface to form adsorbed species.

[0125] In some embodiments, the first step is self-limiting. In some examples, when there is limited availability for substrate surface molecules to react with the first reactant species in the gas phase, it ensures that the reaction is essentially self-limiting. Additionally, the formed reaction layer itself can introduce self-limiting behavior.

[0126] In some embodiments, excess first gas-phase reactant and any reaction by-products are removed from the vicinity of the substrate surface. The first gas-phase reactant and any reaction by-products may be removed from the proximity of the substrate surface with the aid of a purge gas and / or vacuum. In some embodiments, excess reactant and / or reactant by-products are removed from the reaction space by purging, for example, with an inert gas. In some embodiments, the substrate can be moved to facilitate removal of reactants and / or reactant by-products from the vicinity of the substrate, for example, by moving the substrate to a different reaction chamber.

[0127] In a second stage, the second vapor-phase halide reactant can contact the substrate and convert the adsorbed species to a gas-phase reaction product. The reaction product contains atoms of the original material, thereby etching the material. In some embodiments, the second reactant contains the same halide as the first reactant. In some embodiments, the second reactant does not contain reactive species. The excess second reactant and the gas-phase reaction product are removed from the substrate surface, for example, with the aid of a vacuum and / or a purge gas. In some embodiments, the excess second reactant and reaction by-products are removed from the reaction space, for example, by purging with an inert gas. In some embodiments, the substrate can be moved, for example, by moving the substrate to a different reaction chamber, to facilitate removal of the reactant and / or reaction by-products from the vicinity of the substrate.

[0128] To adjust the etching rate and / or to affect one or more properties of the remaining film after the etched film (e.g., resistivity adjustment, e.g., by a factor of, or more than 1%, or more than 5%, or more than 20%, or more than 50%, or more than 100% increase or decrease in post-etch resistivity, e.g., by a factor of, or more than 1%, or more than 5%, or more than 20%, or more than 50%, or more than 100% increase or decrease in optical parameters such as (n,k) of the post-etch, e.g., by a factor of, or more than 1%, or more than 5%, or more than 20%, or more than 50%, or more than 100% increase or decrease in film roughness such as post-etch roughness, and, e.g., by a factor of, or more than 1%, or more than 5%, or more than 20%, or more than 50%, or more than 100% increase or decrease in etching selectivity such as post-etch selectivity improvement, etc.), additional steps may be added, removed, or left free. In some embodiments, a second reactant (such as CCl4) can be used alone without the first reactant and can provide the desired etching selectivity for the desired controlled etching. In some embodiments, one or more additional reactants such as an oxygen reactant such as oxygen, water, or ozone can be provided in a separate step.

[0129] In some embodiments, a third step is added by depositing a third gas-phase reactant. Thereafter, the third step may be removed to adjust the etching rate and / or to affect the etched material. A fourth step is added by depositing a fourth gas-phase reactant. Further, additional phases are added by depositing additional gas-phase reactants.

[0130] One or more reactants may be supplied using a carrier gas such as Ar or He. In some embodiments, the first reactant and the second reactant are provided with the aid of a carrier gas. In some embodiments, the carrier gas may flow continuously throughout the process. In some embodiments, the carrier gas may also function as a purge gas.

[0131] The first and second stages together form an ALE etching cycle that controllably removes material from the substrate surface. The ALE etching cycle may be repeated two or more times to etch the material on the substrate surface to a desired degree. In some embodiments, the ALE etching cycle is repeated 10, 20, 50, 100, 200, 400, 600, 800, 1000 or more times to remove a desired amount of material.

[0132] In some embodiments, the two stages overlap or are combined. For example, the first reactant and the second reactant may simultaneously contact the substrate in stages that partially or fully overlap. Further, although referred to as the first and second stages, and the first and second reactants, the order of the stages may vary and the ALE cycle may begin with any one of the stages.

[0133] By using gaseous reactants, the conformality of the etching process is very good, and the material can be uniformly removed from all surfaces of the three-dimensional structure. In some embodiments, the conformality of the etching is greater than about 90% in the vertical direction, and the conformality of the etching is greater than about 92% in the horizontal direction. In some embodiments, the conformality of the etching of the vertical opening is about 50% or more, about 75% or more, about 85% or more, about 90% or more, about 95% or more, about 98% or more, about 99% or more, and even up to about 100%. In some embodiments, the conformality of the etching in an opening extending in the horizontal direction (e.g., from a vertical opening) is about 50% or more, about 75% or more, about 85% or more, about 90% or more, about 95% or more, about 98% or more, about 99% or more, and even up to about 100%. In some embodiments, the process includes periodically applying two or more stages, more than three stages, or more than four or more than five stages.

[0134] In some embodiments, a substrate including a material to be etched, such as a semiconductor workpiece, is loaded into a reaction space or reactor. The reactor may be part of a cluster tool in which various different processes in the formation of integrated circuits are performed. In some embodiments, a flow-type reactor is used. In some embodiments, a showerhead type of reactor is used. In some embodiments, a spatially divided reactor is utilized. In some embodiments, a high-volume manufacturable single-wafer atomic layer deposition reactor is used. In other embodiments, a batch reactor including a plurality of substrates is used.

[0135] Examples of suitable reactors that can be used include commercially available devices available from ASM America, Inc., Phoenix, Arizona, and ASM Europe B.V., Almere, the Netherlands, such as the F-120® reactor, the F-450® reactor, the Pulsar® reactor, such as the Pulsar® 2000, and the Pulsar® 3000-EmerALD® reactor, and the Advance® 400 series reactors. Other commercially available reactors include the reactors named Eagle® XP and XP8, manufactured by ASM Japan Co., Ltd. (Tokyo, Japan). In some embodiments, the reactor is an etching reactor.

[0136] In some embodiments, if necessary, the exposed surface of the workpiece can be pretreated to react with the reaction site in the first stage of the ALE process. In some embodiments, a separate pretreatment step is not necessary. In some embodiments, the substrate is pretreated to provide a desired surface termination. In some embodiments, the substrate is pretreated with plasma.

[0137] Reactants such as the first reactant and the second reactant are supplied to the reaction space in gaseous form. The first reactant and the second reactant gas are considered "volatile" for the purposes of this specification when the species exhibits a sufficient vapor pressure under the process conditions for carrying the species to the workpiece at a concentration sufficient to saturate the surface where the species is exposed.

[0138] In some embodiments, the reactant is pulsed into a reaction chamber containing a substrate whose surface is etched for about 0.01 to about 60 seconds, about 0.05 to about 30 seconds, about 0.05 seconds to about 5.0 seconds, about 0.1 seconds to about 3 seconds, or about 0.2 seconds to about 1.0 seconds. In some embodiments, the pulse time may be greater than 60 seconds, for example 120 seconds or more. In some embodiments, the reactant contacts the surface of the substrate being etched for about 0.01 seconds to about 60 seconds, about 0.05 seconds to about 30 seconds, about 0.05 seconds to about 5.0 seconds, about 0.1 seconds to about 3 seconds, or about 0.2 seconds to about 1.0 seconds. In some embodiments, the pulse time may be greater than 60 seconds, for example up to 120 seconds. The optimal time can be readily determined by one of ordinary skill in the art based on the particular circumstances.

[0139] As described above, after approximately one molecular layer has had sufficient time to react with the material being removed on the substrate surface to form adsorbed species, if there are excess first reactants and reaction by-products, they are removed from the substrate surface. In some embodiments, removing them when there are excess reactants and reaction by-products can include purging the reaction chamber. In some embodiments, the reaction chamber may be purged by stopping the flow of the first reactant while flowing a carrier gas or purge gas for a time sufficient to diffuse or purge them from the reaction space if there are excess reactants and reactant by-products. The reaction by-products can include, for example, oxyhalides. In some embodiments, the excess first reactant is purged using an inert gas such as helium or argon that flows throughout the ALE cycle. In some embodiments, the substrate may be moved from a reaction space containing the first reactant to a second, different reaction space. In some embodiments, the first reactant is removed for about 0.01 seconds to about 60 seconds, about 0.05 seconds to about 30 seconds, about 0.1 seconds to about 10 seconds, about 0.3 seconds to about 5 seconds, or about 0.3 seconds to about 1 second. In some embodiments, it may be more than 60 seconds.

[0140] In the second stage, a second reactant (such as CCl4) is provided to the workpiece. Typically, the second reactant is pulsed into a reaction chamber containing a substrate having a surface to be etched for about 0.01 to about 60 seconds, about 0.05 to about 30 seconds, about 0.05 seconds to about 5.0 seconds, about 0.1 seconds to about 3 seconds or about 0.2 seconds to about 1.0 seconds. In some embodiments, the second reactant contacts the substrate surface to be etched for about 0.05 seconds to about 5.0 seconds, about 0.1 seconds to about 3 seconds or about 0.2 seconds to about 1.0 seconds. In some embodiments, the pulse may be greater than about 60 seconds. However, depending on the type of reactor, the material being etched, and other process conditions such as surface area and temperature, the second reactant contact time may be even higher than about 10 seconds. In some embodiments, the contact time can be on the order of minutes. One of ordinary skill in the art can readily determine the optimal contact time based on the specific situation.

[0141] The second reactant reacts with the adsorbed species to form gas phase reaction by-products containing atoms of the material being etched. The excess second reactant and gas phase reaction by-products are removed from the reaction chamber. In some embodiments, removing the excess reactant and reaction by-products can include purging the reaction chamber. In some embodiments, the reaction chamber may be purged by stopping the flow of the second reactant while continuing to flow a carrier gas or purge gas for a time sufficient to diffuse or purge the excess reactant and reactant by-products from the reaction space. In some embodiments, the excess second reactant and reaction by-products are purged using an inert gas such as helium or argon. In some embodiments, the substrate may be moved from a reaction space containing the second reactant to a different reaction space. The purge gas pulse can be, in some embodiments, about 0.1 seconds to about 10 seconds, about 0.1 seconds to about 4 seconds or about 0.1 seconds to about 0.5 seconds.

[0142] According to some embodiments, the ALE cycle can be carried out at a temperature in the range of about 20 to about 1200 °C, about 50 to about 800 °C, about 75 to about 600 °C, about 300 °C to about 500 °C, or about 350 °C to about 450 °C. In some embodiments, the temperature is higher than about 20, 50 or 100 °C but less than about 1000, 800, 600, or 500 °C. In some embodiments, the cycle is carried out at a temperature of about 450 °C.

[0143] The pressure in the reaction chamber is typically about 10E-9 Torr to about 760 Torr, or about 0.001 to about 100 Torr. However, depending on the particular circumstances, a person skilled in the art can determine the pressure, and in some cases, the pressure will be higher or lower than this range. In some cases, the reactor can operate under either isothermal (such as hot wall) or non-isothermal (such as cold wall) conditions. In some cases, the reactor may not interact with the etching chemistry and thus may not interact with the substrate either. In some cases, the reactor can be a hot wall, cold water, and even warm water wall type reaction chamber.

[0144] The substrate containing the material to be etched, also called the target material, can take various forms. In some embodiments, the substrate can be an integrated circuit workpiece or other substrate. The target material to be etched may include a thin film on the substrate surface. In some embodiments, the target material is a thin film on a three-dimensional structure on the substrate. The substrate containing the thin film or other material to be etched may include various other types of materials. For example, in some embodiments, the substrate may include silicon in addition to the material targeted by the etching process. In some embodiments, the etching process is selective with respect to other materials on the substrate or within the reaction chamber. In some embodiments, to improve selectivity, the first reactant alone, or the second reactant alone, or both the first reactant and the second reactant are supplied periodically.

[0145] In some embodiments, the target material to be etched contains metals such as Ir, Ru, Rh, Mo, Cu, Sb, Al, Ti, Co, Ni, Ta, Al, Zr, Hf, or W. In some embodiments, the material to be etched is W, WO3, AlN, TiN, TiO2, GaN, MoN, CoP, TaN, SiN, SiO x 、AlO x 、AlO2, Al2O3, ZrO x 、ZrO2, and HfO x 、e.g., one or more of HfO2. In some embodiments, the material to be etched contains a metal nitride or a metal oxide or a mixture thereof.

[0146] In some embodiments, a thin film containing one or more of W, TiN, TiO2, TaN, SiN, SiO X 、AlO x 、AlO2, Al2O3, ZrO x 、ZrO2, WO3, AlN, HfO x and HfO2 is etched by an ALE process that includes alternately and sequentially contacting a substrate containing the thin film with NbF5 and CCl4. In some embodiments, a thin film containing one or more of W, TiN, TiO2, TaN, SiN, SiO X 、AlO x 、AlO2, Al2O3, ZrO x 、ZrO2, WO3, AlN, HfO x and HfO2 is etched by an ALE process that includes alternately and sequentially contacting a substrate containing the thin film with a first reactant and a second reactant, and the first reactant and the second reactant contain the same halide.

[0147] In some embodiments, the ALE process has an average etching rate of from about 0.01 to about 5 Å / cycle. The etching rate is defined as the amount of material or film thickness removed after each cycle for practical reasons that can be calculated after one etching cycle, or more than two etching cycles, or more than five, or even more than twenty or sometimes more than fifty cycles. In some embodiments, the average etching rate is from about 0.01 to 0.1 Å / cycle, or from 0.1 to about 2 Å / cycle or in some cases higher than 2 Å / cycle. In some embodiments, the average etching rate is greater than about 0.1 Å / cycle, greater than about 0.5 Å / cycle, greater than about 1.0 Å / cycle, greater than about 2.0 Å / cycle, greater than about 3.0 Å / cycle, greater than about 5.0 Å / cycle, greater than about 10 Å / cycle, or greater than about 20 Å / cycle. In some examples, when applying a flow rate change in a continuous flow or when the exposure time is sufficient, the etching rate can be greater than about 30 Å / cycle, greater than about 50 Å / cycle, or greater than about 100 Å / cycle.

[0148] In some embodiments, the etching selectivity, i.e., the ratio of the material removed from the desired surface / material to the material removed from the undesired surface / materials or multiple surfaces / materials (thickness, mass or amount of atoms / molecules) is greater than about 2:1, greater than about 3:1, greater than about 5:1, greater than about 7:1, greater than about 10:1, greater than about 15:1, greater than about 20:1, greater than about 30:1, greater than about 50:1, greater than about 100:1, greater than about 1000:1. In some embodiments, no substantial amount of material is removed from the undesired surface / material.

[0149] In some embodiments, the flow or the first or second reactant can be higher than 2 sccm, greater than 10 sccm, or even higher than 50 sccm, and can be more than 100 sccm or more than 500 sccm, etc. In some embodiments, the first reactant can flow continuously into the reaction chamber while the second reactant flows intermittently.

[0150] Figure 1 is a flowchart generally showing an embodiment of the ALE method. The ALE method illustrated in Figure 1 includes a first exposure step 100, a first removal step 110, a second exposure step 120, and a second removal step 130.

[0151] In some embodiments, a substrate having an etching target material is placed in a reaction chamber and exposed to a first gas-phase reactant in the first exposure step 100. The etching target is generally exposed to the first gas-phase reactant for the above-mentioned period of time. In some embodiments, the pulse time is about 0.1 - 10 seconds, or 0.1 - 5 seconds.

[0152] After the first exposure step 100, the excess first gas-phase reactant is removed from the reaction chamber in the first removal step 110. The reaction chamber may be evacuated with a vacuum pump and / or evacuated by replacing the gas in the reactor with an inert gas such as argon or nitrogen. The removal step 110 can typically take about 0.05 - 20 seconds. However, the removal step can take more or less time as needed.

[0153] Thereafter, the substrate is exposed to a second gas-phase reactant in the second exposure step 120. The second reactant may be the same as the first gas-phase reactant. The etching target is generally exposed to the second gas-phase reactant for the above-mentioned period, for example, for about 0.1 second to 10 seconds.

[0154] After the second exposure step 120, excess second vapor-phase halide reactants and volatile reaction by-products are removed from the reaction chamber of the second removal step 130. In some embodiments, the first exposure step 100, the first removal process 110, the second exposure step 120, and the second removal step 130 form an ALE etch cycle 150 that can be repeated until the desired amount of etching of the target material is obtained. In some embodiments, the first exposure step 100, the first removal process 110, the second exposure step 120, and the second removal step 130 may be repeated in 10, 20, 50, 100, 200, 500, 1000 or more cycles.

[0155] In some embodiments, the etching target material includes metals such as W, Pt, Cu, Ni, Co, Ti, Zn, Nb, Mo, Ta. In some embodiments, the etching target material includes metal nitrides such as, for example, MoN, NbN, SiN, TiN, TAN, WN, AlN. In some embodiments, the etching target material includes carbides such as SiC, TiC, TAC, AlC, HfC, MoC, NbC. In some embodiments, the etching target material includes oxides such as dielectric oxides such as, for example, AlOx, ZRox, HfOx, TiOx, TaOx, NbOX, MoOx, SiOx, LaoX. In some embodiments, the etching target material includes 2D materials and / or sulfides such as WS2, Mos2, Tis2, SNs2. In some embodiments, the etching target material includes metal oxynitrides similar to TiONx, metal carbonitrides such as WNC, oxycarbides, for example, and elemental substrates such as Si, C, a-C, graphene.

[0156] In some embodiments, the first reactant includes Nb, Ta, Mo or W.

[0157] Referring to FIG. 2, according to some embodiments, on the substrate in the reaction space, W, TiN, TiO2, TaN, SiN, SiO X , AlO x , AlO2, Al2O3, ZrOx , ZrO2, WO3, AlN, HfO x An etching target thin film containing or HfO2 is etched by an ALE process including at least one etching cycle 240, and this etching cycle is such that in step 200, the substrate contacts a gas-phase metal chloride reactant without excited species so that the metal chloride reactant reacts with the thin film on the surface of the substrate to form adsorbed species, removal in step 210 if there are excess metal chloride reactants and reaction by-products from the substrate surface, contacting the substrate with a second chloride reactant without reactive species in step 220, thereby converting the adsorbed species into gas-phase reaction by-products containing atoms of the etching target thin film, removal in step 230 if there are excess second chloride reactants and reaction by-products from the substrate surface, and optionally repeating the contacting and removal steps in step 240 to etch the etching target thin film to a desired degree.

[0158] Referring to FIG. 3, according to some embodiments, on a substrate within a reaction space, W, TiN, TiO2, SiOC, SICN, SiOCN, SiON, TaN, SiN, SiO X , AlO x , AlO2, Al2O3, ZrO x , ZrO2, WO3, AlN, HfO x An etching target thin film containing or HfO2 is etched by an ALE process including at least one etching cycle 340, and this etching cycle 340 includes contacting the substrate with gas-phase NbF5 in step 300, removal in step 310 if there are excess NbF5 and reaction by-products from the substrate surface, contacting the substrate with gas-phase CCl4 in step 320, removing excess CCl4 and reaction by-products from the substrate surface in step 330, and optionally repeating the contacting and removal steps in step 340 to etch the etching target thin film to a desired degree.

[0159] Referring to FIG. 4, according to some embodiments, on a substrate within a reaction space, W, TiN, TiO2, TaN, SiN, SiOX , AlO x , AlO2, Al2O3, ZrO x , ZrO2, WO3, AlN, HfO x An etching target thin film containing HfO or HfO2 is etched by an ALE process including at least one etching cycle 440. This etching cycle includes, in step 400, contacting the substrate with a gas-phase metal halide reactant free of excited species such that the metal halide reactant reacts with the thin film on the surface of the substrate to form adsorbed species; removing, in step 410, excess metal halide reactant and reaction by-products, if any, from the substrate surface; contacting, in step 420, the substrate with a second organic reactant free of reactive species, thereby converting the adsorbed species into gas-phase reaction by-products containing atoms of the etching target thin film; removing, in step 430, excess second organic reactant and reaction by-products, if any, from the substrate surface; and optionally repeating the contacting and removing steps in step 440 to etch the etching target thin film to a desired degree.

[0160] Referring to FIG. 5, according to some embodiments, on the substrate in the reaction space, W, TiN, TiO2, TaN, SiN, SiO X , AlO x , AlO2, Al2O3, ZrO x , ZrO2, WO3, AlN, HfO xThe etching target thin film containing HfO2 is etched by an ALE process including at least one etching cycle 540, and this etching cycle includes, in step 500, contacting the substrate with a gas-phase metal halide reactant without excited species so that the metal halide reactant reacts with the thin film on the surface of the substrate to form adsorbed species; removing excess metal halide reactant and reaction by-products from the substrate surface in step 510 if any; contacting the substrate with a second adduct-forming reactant without reactive species in step 520, thereby converting the adsorbed species into a volatile adduct containing atoms of the etching target thin film; removing excess second adduct-forming reactant and reaction by-products from the substrate surface in step 530 if any; and optionally repeating the contacting and removing steps in step 440 to etch the etching target thin film to a desired degree.

[0161] According to some embodiments, in a substrate within a reaction space, an etching target thin film containing Al2O3, HfO2, TiO2 or another metal oxide is etched by an ALE process including at least one etching cycle, and this etching cycle includes contacting the substrate with a first gas-phase reactant containing a metal halide or CCl4 without excited species so that the first reactant reacts with the thin film on the surface of the substrate to form adsorbed species; removing excess first reactant and reaction by-products from the substrate surface if any; contacting the substrate with a second organic reactant containing 1,4-dioxane without reactive species, thereby converting the adsorbed species into a volatile adduct containing atoms of the etching target thin film; removing excess second organic reactant and reaction by-products from the substrate surface if any; and optionally repeating the contacting and removing steps to etch the etching target thin film to a desired degree.

Example

[0162] SiO2 (thermal and natural) 、 TiN, TiO x , TaN, AlO x , AlN, ZrOx and HfO x Thermal ALE was used to etch thin films of. The ALE cycle involves contacting a substrate containing the relevant film with NbF5 and CCl4; a mixture of NbF5 and CCl4 with H2O; a mixture of NbF5 and CCl4 with O3; or CCl4 alone, alternately and sequentially. As shown in Table 1 below, etching of each of the various types of thin films was observed, and the etching rate was in the range of about 0.1 Å / cycle to about 1.8 Å / cycle. No etching of the SiO2 film, or SiO x or SiN x was observed.

Table 1

[0163] Figure 6 is a graph showing the differences in mass, thickness, and sheet resistance after thermal ALE treatment of TiN, TiO2, SiN, TaN, ZrO2, and Al2O3. Substrates containing thin films of each material were placed in Pulsar2000 (trademark) reactants. The thermal ALE cycle included alternate and continuous pulses of NbF5 and CCl4. The temperature of the substrate was about 450 °C (the susceptor temperature was 465 °C and the maximum plate temperature was 405 °C). After 1000 ALE cycles for SiO 2、 Tin, TiO 2、 SiN, and TaN films, and after 100 cycles for ZrO 2、 SiN, and TaN films, and after 100 cycles for ZrO 2、 Al2O3 and TiO2 films, the mass, thickness and sheet resistance were measured. Significant changes were observed for TiN, TiO2, TaN, ZrO2, and Al2O3 from the graph. For TiO2, after 1000 etching cycles, the entire layer was consumed and the film thickness decreased by about 40 nm. After 100 cycles, the thickness decreased by about 20 nm. For TaN, the mass decreased by about 22 mg and the sheet resistivity increased by about 11 Ω / □ after about 1000 cycles. For ZrO2, the thickness decreased by about 5 nm after 100 cycles. For Al2O3, the thickness decreased by about 11 nm after 100 cycles.

[0164] Figure 7 is a graph showing the change in weight and sheet resistance of TiN and TaN films at a reaction temperature of about 450 °C after varying the number of ALE cycles using NbF5 and CCl4. Visual inspection revealed complete removal of the 20 nm TiN film at the center of the wafer after 400 cycles.

[0165] Figure 8 is a graph showing the removed mass (mg) of AlN, TiN, HfO2, and TaN target films that have undergone various thermal atomic layer etch processes as described herein and according to several embodiments. Each target film was etched at various reaction or etching temperatures for each process. It was unexpected that an atomic layer etch process involving NbF5 as the first reactant and triethylaluminum (TEA) or trimethylaluminum (TMA) as the second reactant led to the removed mass from the TaN and AlN target films.

[0166] Figure 9 is a graph showing the removed mass (mas) (mg) of TiN, AlN, AlOx, HfOx, TaN, SiN, and thermal oxide target films that have undergone various thermal atomic layer etch processes as described herein and according to several embodiments. Each target film was etched at various etching temperatures for each process. It was unexpected that an ALE process involving NbF5 and TEA as the first and second reactants, an ALE process using TEA and CCl4 as the first and second reactants, and an ALE process using NbF5, TEA, and CCl4 as reactants led to the removed mass from the target films.

[0167] Those skilled in the art will understand that various modifications and changes can be made without departing from the spirit of the present invention. Similar other modifications and changes are intended to fall within the scope of the present invention as defined by the appended claims.

Claims

1. A method for etching a film on the surface of a substrate in a reaction chamber by chemical atomic layer etching, the method including one or more etching cycles, each cycle comprising exposing the substrate to a first gas-phase halide reactant containing a first halide ligand to form an adsorbed species on the substrate surface, wherein the first gas-phase halide reactant does not contain hydrogen, forming, and subsequently exposing the substrate to a second gas-phase halide reactant containing a second halide ligand that converts the adsorbed species to volatile species such that at least some of the material is removed from the film, wherein the second gas-phase halide reactant does not contain hydrogen, exposing, and the substrate not being in contact with a plasma reactant during the etching cycle.

2. The film is W, TiN, TiO ２ , TaN, SiN, AlO ２ , Al ２ O ３ , ZrO ２ , WO ３ , SiOCN, SiOC, SiCN, AlN, or HfO ２ The method according to claim 1, comprising

3. The method of claim 1, wherein the first gas-phase halide reactant contains a metal halide.

4. The method of claim 3, wherein the metal halide contains a metal selected from Nb, Ta, Mo, Sn, V, Re, Te, W, and transition metals of groups 5 and 6.

5. The method of claim 1, wherein the first gas-phase halide reactant does not contain a metal.

6. The method of claim 1, wherein the first gas-phase halide reactant contains an organic halide compound.

7. The method of claim 1, wherein the first gas-phase halide reactant contains an alkyl halide, an acyl halide, a sulfonyl halide, a sulfenyl halide, a selenyl halide, or a boron halide containing an organic ligand.

8. The method of claim 1, wherein the first gas-phase halide reactant contains fluorosulfonic acid, trifluoromethanesulfonic acid, trifluoromethyltrifluoromethanesulfonate, sulfatetrafluoride sulfachloride pentafluoride, or sulfur hexafluoride, or 1-chloro-2-(pentafluorosulfanyloxy)ethane.

9. The method of claim 1, wherein the first gas-phase halide reactant contains chlorosulfonyl isocyanate or N,N-dimethylsulfamoyl chloride.

10. The method of claim 1, wherein the first gas-phase halide reactant contains boron, hydrogen, and a halide.

11. The method according to claim 1, wherein the first gas-phase halide reactant contains phosphorus, oxygen, and a halide.

12. The method according to claim 1, wherein the first gas-phase halide reactant contains antimony and a halide.

13. The method according to claim 1, wherein the first gaseous halide reactant comprises one or more -CF ３ groups.

14. The method according to claim 1, further comprising sequentially repeating the etching cycle two or more times.

15. The method according to claim 1, wherein the first and second halide ligands are Cl.

16. The method according to claim 1, wherein the second gas-phase halide reactant does not contain a metal.

17. The method according to claim 1, wherein the second gas-phase halide reactant is a carbon-based halide.

18. The second gas-phase halide reactant is CCl ４ or CBr ４ The method according to claim 17, comprising.

19. The method according to claim 1, wherein the temperature of the substrate during the etching cycle is 300°C to 500°C.

20. A method of etching a film on a surface of a substrate in a reaction chamber by chemical atomic layer etching, the method comprising one or more etching cycles, each cycle comprising: exposing the substrate to a first gas-phase reactant such that the first gas-phase reactant reacts with molecules on the substrate surface to form a reactant species on the substrate surface; and subsequently exposing the substrate to a second gas-phase reactant such that the reactant species is converted into a volatile reaction product and a portion of the film is removed from the substrate surface, wherein the substrate does not contact a plasma reactant during the etching cycle.

21. The first gas-phase reactant is CSe ２ The method according to claim 20, comprising

22. The method according to claim 20, wherein the first gas-phase reactant contains a compound having an S=R=S structure, where R may be carbon or any hydrocarbon such as C2-C8.

23. The first gas-phase reactant is CS ２ The method according to claim 22, comprising

24. The method according to claim 20, wherein the second gas-phase reactant contains triethylaluminum (TEA) or trimethylaluminum (TMA).

25. A method of etching a film on a substrate in a reaction chamber, comprising two or more etching cycles, each cycle comprising: exposing the substrate to a first gas-phase halide reactant that does not contain hydrogen; and subsequently exposing the substrate to a second different gas-phase halide reactant that does not contain hydrogen; and exposing the substrate to a third gas-phase reactant different from the first and second gas-phase reactants. A method in which the substrate is not in contact with plasma reactants during the etching cycle.

26. The additional gas-phase reactants are one or more SO ３ , H ２ S, NH ３ , H ２ O, HCOOH, H ２ O ２ and hydrazine, and the method according to claim 25.

27. A method of etching a thin film on a substrate surface, the method comprising: exposing the substrate surface to a first gas-phase halide reactant containing a first halide ligand to form a first reactant species on the substrate surface, wherein the first gas-phase halide reactant does not contain hydrogen; and subsequently, exposing the substrate to a second gas-phase halide reactant containing a second halide ligand such that the second gas-phase halide reactant converts the first reactant species into a gas-phase reaction product, wherein the second gas-phase halide reactant does not contain hydrogen, wherein the formation of the first reactant species or the conversion of the second gas-phase halide reactant into the gas-phase reaction product is not self-regulated.

28. The method according to claim 27, wherein the substrate is not in contact with plasma reactants during the etching cycle.

29. The method according to claim 27, wherein the formation of the first reactant species and the conversion of the second gas-phase halide reactant into the gas-phase reaction product are not self-regulated.

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