Processes for deposition of elemental germanium

Abstract

The present application describes processes for depositing a material comprising elemental germanium, comprising use of a germanium-containing precursor compound in combination with a base-free hydroborane, hydrosilane, hydrostannane, or hydroalane co-reactant.

Description

PROCESSES FOR DEPOSITION OF ELEMENTAL GERMANIUMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of priority from co-pending U.S. provisional application no. 63 / 563,012 filed on March 8, 2024, the contents of which are incorporated herein by reference in their entirety.FIELD

[0002] The present application relates, for example, to processes for depositing materials such as films comprising elemental germanium.BACKGROUND

[0003] Germanium is an element located directly below silicon in the periodic table and is an important semiconductor material with a range of existing and emerging applications, including in semiconductor devices, photonic devices, and quantum technologies. However, methods to deposit thin films of elemental germanium are scarce.

[0004] Atomic layer deposition (ALD) is typically a cyclic vapour deposition process involving self-limiting surface-based chemical reactions between two or more different chemical precursors that are sequentially delivered to a substrate surface in the vapour phase, separated by inert gas purge steps, where a function of these purge steps is to remove excess precursor and reaction byproducts from the reaction chamber before introduction of the next precursor. Therefore, a typical ALD process comprises one or more cycles comprising a pulse of the first precursor, followed by a purge step to remove excess precursor and reaction byproducts from the reaction chamber, followed by a pulse of a second precursor, followed by a purge step to remove excess precursor and reaction byproducts from the reaction chamber. A defining feature of ALD is self-limiting growth, wherein the film growth rate is independent of the duration of each precursor pulse, provided that each precursor pulse is above a certain minimum duration.

[0005] ALD allows the deposition of ultra-thin films that have greater thickness uniformity and conformality than films deposited by other methods, such as chemical vapour deposition (CVD) and physical vapour deposition (PVD). CVD is a vapour deposition process in which one or more precursor molecules are delivered to a substrate surface in the vapour phase, but the process does not achieve self-limiting growth; a common form of CVD involves thermal decomposition of a single precursor on the surface of a heated substrate, but CVD processesinvolving multiple precursors, with or without purge steps between each precursor pulse are also known. PVD techniques include sputtering and evaporation.

[0006] Consequently, ALD is often the preferred method for thin film deposition (primarily for films less than 300 nm in thickness, such as films less than 100 nm or 50 nm or 20 nm or 10 nm in thickness) during device fabrication (e.g. in the semiconductor industry). It may also be advantageous over solution deposition methods due, for example, to increased film uniformity and conformality, avoidance of issues resulting from incomplete surface contact with the solution, and / or more practical use in semiconductor fabrication, especially relative to non-aqueous solution deposition methods requiring moisture-free and / or oxygen-free conditions.

[0007] Plasma-Enhanced ALD (PEALD) refers to an ALD process in which one or more precursors is a plasma-generated species. In contrast, the term thermal ALD refers to an ALD process in which none of the precursors are plasma-generated species.

[0008] Several methods for germanium PEALD (e.g. using GeCL or NfeGelE in combination with hydrogen plasma) have been reported (S. Sugahara, et al., Appl. Surf. Sci. 1994, 82 / 83, 380, Appl. Surf. Sci. 1995, 90, 349, Jpn. J. Appl. Phys. 1997, 36. 1609, Appt. Surf Sci. 1998, 130-132, 327, and M. Matsuyama, et al., Jpn. J. Appl. Phys. 2000, 39, 2536). However, thermal ALD is typically advantageous relative to plasma-enhanced ALD (PEALD) because it avoids plasma-induced surface damage, reduces the cost and complexity of the reactors required for deposition, and enables more conformal deposition on high aspect-ratio substrates because in PEALD, radical recombination can greatly reduce the availability of radicals, and therefore the deposition rate, at the bottom of deep trenches.

[0009] Methods for germanium deposition involving adsorption of a monolayer of a precursor (Et2GeH2, GeH4 or Ge2He), followed by rapid heating to induce thermal decomposition have been described (Y. Takahashi, et al. , J. Electrochem. Soc. 1989, 136, 1826 and Jpn. J. Appl. Phys. 1989, 28(11), 2387; N. Mikoshiba, et al., J. Cryst. Growth 1991, 115, 79 and Journal de Physique IV Proceedings 1991, 02 (C2), C2-803; J. Munota, et al., Appl. Surf. Sci. 1994, 82 / 83, 354; K.-H. Huang, T.-S. Ku, D.-S. Lin, Phys. Rev. B 1997, 56(8), 4878; D.-S. Lin, et al. , Phys. Rev. Lett. 2003, 90(4), 046102-1; P. A. Coon, M. L. Wise, A. C. Dillon, S. M. George, Mat. Res. Soc. Symp. Proc. 1993, 282, 413). However, these methods do not involve a precursor molecule and a co-reactant molecule, and fall outside of the standard definition of thermal ALD.

[0010] Thermal ALD, which involves surface-based chemical reactions between two or more precursors, is typically advantageous relative to methods that involve just one precursor combined with heating steps to achieve precursor decomposition within each deposition cycle. This is because precursor heating by traditional means (e.g., resistive heating) will result in extremely long deposition cycle times, and laser or flash lamp heating requires a substantially more costly and complex reactor, and is less likely to be effective for uniform and conformal deposition on high aspect-ratio substrates where regions of the surface are out of the line of sight of the light used for heating.

[0011] Solution reactions of potential germanium precursor / co-reactant pairs are disclosed in K.C. Wedisinghe, “Synthesis and Development of Precursor Molecules and Reactions for Atomic Layer Deposition (ALD) of Elemental Zn and Ge” MSc Thesis, McMaster University, April 2021. Sinclair et al. in “Access to metastable IGeFLIn materials via a molecular bottom- up approach”, Dalton. Trans., 2021, 50, 17688-17696 disclose a hydride metathesis protocol for the preparation of metastable germanium(II) dihydrides with compositions approaching [GeH2]„. Sinclair et al. also disclose that heating one of these materials to 200°C affords the generation of amorphous Ge. Certain atomic layer deposition methods for producing a germanium thin fdm using an organic germanium compound and a reducing gas have been disclosed. WO2015 / 132445A1 generally discloses a method of depositing elemental germanium on substrates comprising sequentially exposing a substrate inside a deposition chamber with a germanium precursor and a reducing gas. However, the only specific reducing precursors are disclosed to be selected from the group consisting of H2 and hydrogen plasma.

[0012] Borane dimethylamine has been disclosed for use as a reducing agent in an atomic layer deposition method to deposit a germanium film. However, the hydroborane- Lewis base adduct HsBNMe2H has been reported to exhibit unique behaviour as a reducing agent, where it has been suggested to form an unidentified highly reducing species upon contact with certain materials, such as platinum, palladium, and ruthenium, resulting in film deposition that only occurs on certain substrate surfaces and ceases when the original substrate surface is no longer accessible (see for example: Winter et al., J. Am. Chem. Soc. 2013, 135, 12588-12591 and Chem. Mater. 2014, 26, 3731-3738). While not wishing to be limited by theory, the unidentified highly reducing species may be [BH2NMe2]2, given that HsBNMe2H has been reported to decompose thermally to [BH2NMe2]2 and H2 at 130 °C (as mentioned in Winter et al., Chem. Mater. 2014, 26, 3731-3738; see also Manners et al.,J. Am. Chem. Soc. 2003, 125, 9424-9434.), and it is reasonable that this decomposition is catalyzed by certain metals. Consequently, HsBNNfeH in these examples does not simply act as a source of BH3, and analogous reactivity would not be accessible for other hydroborane-Lewis base adducts that lack a hydrogen substituent on the atom coordinated to boron, such as HsBNMes, HsBPMes or HsBSNfe.SUMMARY

[0013] The present application includes a process for depositing a material comprising elemental germanium, the process comprising a deposition cycle comprising: exposing a heated substrate to a vapor comprising a germanium-containing precursor compound; and exposing the heated substrate to a vapor comprising a co-reactant selected from a base-free hydroborane, a hydrosilane, a hydrostannane and a hydroalane.

[0014] The present application also includes a process for preparing a binary, ternary or quaternary material, a doped material, or a nanolaminate, the process comprising: depositing a fdm comprising elemental germanium by a process as described herein; and one or more additional fdm deposition processes.

[0015] The present application also includes a use of a process as described herein in the fabrication of an electronic device, memory or logic device, photonic device or quantum device.

[0016] This application also discloses a cyclic fdm deposition process that results in the deposition of a film comprising elemental germanium, with each cycle comprising sequentially contacting a heated substrate with vapours of a germanium-containing compound (precursor- A), and contacting the substrate with vapours of a second precursor (precursor-B) selected from a base-free hydroborane, a hydrosilane, a hydrostannane, or a hydroalane.

[0017] In one embodiment, the germanium-containing compound (precursor- A) contains germanium bound exclusively to oxygen, nitrogen and / or chlorine atoms. In another embodiment, the germanium-containing compound (precursor-A) contains germanium bound exclusively to oxygen and / or nitrogen atoms. In one refinement, precursor-A is a germanium(IV) or germanium(II) alkoxide or amide compound, where one substituent of the alkoxide or amide group may contain an additional ether or amine donor. In another refinement, precursor-A is selected from Ge(OR1)4, Ge(NR2R3)4, Ge(OR4)2, Ge(NR5R6)2, or GeN(SiR7R8R9)2 whereinR1, R2, R3and R5are independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, CH2'Bu. CH2"BU, CH2'BU. CH2SiMe3, cyclopentyl, and 1- norbomyl, and R4and R6are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu. 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH Bu, CH2'Bu. CH2SiMe3, cyclopentyl, 1- norbomyl, CR10RnCH2NR12R13, CR10'R11'CH2CH2NR12'R13', CH2CR10R11'CH2NR12R13', CR10RnCH2OR12, CR10RnCH2CH2OR12, and CH^R^'R^'CH^R12' wherein R10' and R11are independently selected from H, Me, Et, "Pr and 'Pr and R12and R13are independently selected from Me, Et, "Pr, and 'Pr, and R7, R8and R9are independently selected from Me, Et, "Pr, and 'Pr. A preferred composition of precursor-A is Ge(OR4)2, most ideally Ge(OCR10RnCH2NR12R13)2with the R-groups selected from those specified in this paragraph.

[0018] Precursor-B in this film deposition process is selected from (a) a base-free hydroborane selected from HB(OCR1R2'CR3R4'O), HB(OCR1'R2'CR3'R4'CR5'R6'O), HBcat, (9- BBN)„', (HBR72),,'. or B2He, wherein n' is 1 or 2, the substituents R1, R2, R3, R4, R5and R6are independently selected from H, Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu and 'Bu, and R7is independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu. 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CHfBu. CH2'BU. CH2SiMe3, and cyclopentyl, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMefBu. and CMe2CH2'Bu, (b) a hydrosilane selected from SiEU, H3SiR? , H2SiR? R2, HSiR1R2R3, or H3SiR4, wherein R1', R2' and R3are independently selected from Cl, OMe, OEt, O"Pr, O'Pr, O"Bu, O'Bu, O'Bu. O'Bu, Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CHfBu. CH2'Bu. CH2SiMe3. and cyclopentyl, and R4is an aryl substituent selected from Ph, CefEMe. CefEEt. CeH4"Pr, CeHfPr, CeH3Me2, and C6H2Me3, C6H4(OMe), C6H3(OMe)2, C6H4(CF3), C6H4F, C6H3F2, C6H2F3, C6HF4, or C6F5, (c) a hydrostannane with the formula HSnR1R2R3, wherein R1', R2' and R3are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2"Bu, CFE'Bu. CH2SiMe3, and cyclopentyl, or (d) ahydroalane with the formula (HAIR1R2), , wherein n' is 1 or 2, and R1and R2are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2"Bu, and CMe2CH2'Bu. A preferred composition of precursor-B is a base-free hydroborane (HB(OCR1'R2'CR3'R4'O), HB(OCR1'R2'CR3'R4'CR5'R6'O), HBcat, (9-BBN),,-. (HBR7'2)„-, or B2H6. with R-groups selected from those specified in this paragraph.

[0019] In an embodiment of the present application, the process disclosed herein may be carried out with the use of a purge gas to remove at least a portion of excess vapourphase precursor- A, and reaction byproducts if any, from the reaction space after contacting the substrate with precursor-A and before contacting the surface with precursor-B, and the use of a purge gas to remove at least a portion of excess precursor-B, and reaction byproducts if any, from the reaction space after contacting the substrate with precursor-B and before contacting the surface with precursor-A. This process may be an atomic layer deposition (ALD) process, where self-limiting growth is achieved, or may be a chemical vapour deposition process, where self-limiting growth is not achieved.

[0020] The germanium-containing films resulting from the deposition process disclosed herein may be comprised of elemental germanium, and in some embodiments, the germanium content of the film is greater than or equal to about 80 at%, 85 at%, 90 at%, 95 at%, 98 at%, 99 at% or 99.5 at% within the bulk portion of the film.

[0021] In typical embodiments, the deposition is carried out without addition of hydrogen gas. In some embodiments, the deposition process may be carried out in the presence of a continuous or periodic flow of hydrogen or a mixture of hydrogen in an inert gas. In such embodiments, a continuous flow of hydrogen is for use with precursor combinations (e.g. combinations of precursor-A and precursor-B) where neither precursor on its own reacts appreciably with H2 under the conditions of the deposition experiment.

[0022] The deposition process disclosed in this application is typically carried out with a substrate temperature (i.e. a deposition temperature) between 20 and 500 °C, most typically between 100 and 400 °C. In some embodiments, films comprising germanium are deposited selectively on one material relative to another material. The term “selective deposition” as used herein refers to deposition on a target surface material at a higher rate than on a non-target surface material. The target surface material may be e.g. H-terminated silicon or a metal surface and the non-target surface material may be e.g. SiCh or HfCh. In some embodiments the selectivity (the ratio of film growth rate on a target surface material to the film growth rate on a non-target surface material) is greater than 2, such as greater than 5, or greater than 10. In some embodiments, films comprising elemental germanium are deposited on H-terminated silicon without being substantially deposited on dielectric surfaces, such as silicon oxide, germanium oxide, aluminum oxide, a rare earth metal oxide, titanium oxide, zirconium oxide, hafnium oxide, or tantalum oxide.

[0023] The deposition process disclosed herein may be interspersed with one or more other film deposition process for the purpose of fabricating a binary, ternary or quaternary material, ora nanolaminate. The deposition process disclosed herein may also be used for a broad range of applications, including electronic device fabrication, memory or logic device fabrication, photonic device fabrication, or quantum device fabrication.

[0024] Other features and advantages of the present application will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the application, are given by way of illustration only and the scope of the claims should not be limited by these embodiments but should be given the broadest interpretation consistent with the description as a whole.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Certain embodiments of the application will now be described in greater detail with reference to the attached drawings in which:

[0026] FIG. 1 shows Field Emission Scanning Electron Microscopy (FESEM) images of a film deposited on H-terminated Si in exemplary embodiments of the application for an exemplary film deposited using 1000 cycles.

[0027] FIG. 2 shows Field Emission Scanning Electron Microscopy (FESEM) images of a film deposited on H-terminated Si in exemplary embodiments of the application for an exemplary film deposited using 4000 cycles.

[0028] FIG. 3 shows X-ray Photoelectron Spectroscopy (XPS) Depth Profile Data for the film deposited on H-terminated Si in an exemplary embodiment of the application, showing Cis (*), Bls (**), Si2p (***), Nls (#), Ols (##) and Ge3d (###).

[0029] FIG. 4 shows an X-ray photoelectron spectrum in the Ge 3d binding energy region of the film grown on H-terminated Si after surface sputtering (Etch Level 6) in an exemplary embodiment of the application.

[0030] FIG. 5 shows a graph of average film thickness (nm; left axis, values from VASE) and growth rate per cycle (GPC, A; right axis, values from VASE) as a function of deposition temperature using both SiCL / Si and H-terminated Si substrates. These experiments used 1000 cycles of 0.2s pulses of the germanium- containing precursor, 0.05s pulses of HB(OCMe2CMe2O) (HBpin), and 45s inert gas purge steps after each precursor pulse in an exemplary embodiment of the application.

[0031] FIG. 6 shows graphs of average film thickness (nm, upper graph, values from VASE) and GPC (A; lower graph, values from VASE) as a function of precursor pulse length(for deposition on SiCh / Si and H-terminated Si at 225 or 300 °C) in exemplary embodiments of the application. From top to bottom in upper graph in each datapoint: H-terminated Si at 300 °C, H-terminated Si at 225 °C, SiO Si at 225 °C, and SiCh / Si at 300 °C. From top to bottom in lower graph at each datapoint: H-terminated Si at 225 °C and SiO Si at 225 °C.

[0032] FIG. 7 shows a graph of average film thickness (nm; values from VASE) deposited on H-terminated Si and SiCL / Si as a function of the number of thermal ALD cycles. These experiments were carried out at 225 °C using 0.2s pulses of the germani urncontaining precursor; 0.05s pulses of HBpin, and 45s inert gas purge steps after each precursor pulse in an exemplary embodiment of the application.

[0033] FIG. 8 shows a graph of average film thickness (nm; values from VASE) as a function of the number of ALD cycles using H-terminated Si substrates at 225 °C (circles) and 250 °C (squares). These experiments used 0.2s pulses of the germanium-containing precursor, 0.05s pulses of HBpin, and 45s inert gas purge steps after each precursor / co- reactant pulse in an exemplary embodiment of the application.

[0034] FIG. 9 shows graphs of average film thickness (nm; values from VASE) at 225 °C as a function of germanium-containing precursor pulse length (upper graph) and HBpin pulse length (lower graph) using H-terminated Si substrates in exemplary embodiments of the application.

[0035] FIG. 10 shows a graph of average film thickness (nm; values from VASE) as a function of precursor and co-reactant pulse length using H-terminated Si substrates. These experiments were carried out at 250 °C using either (a) 0.2s pulses the germanium-containing precursor and 0.1s pulses of HBpin or (b) 0.4s pulses of the germanium-containing precursor and 0.2s pulses of HBpin in an exemplary embodiment of the application.

[0036] FIG. 11 shows a graph of average film thickness (nm; values from VASE) as a function of purge duration using an H-terminated Si substrate. These experiments used 0.2s pulses of the germanium-containing precursor and 0.05s pulses of HBpin, and were carried out at 225 °C (circles) or 250 °C (squares) in an exemplary embodiment of the application.DETAILED DESCRIPTIONI, Definitions

[0037] Unless otherwise indicated, the definitions and embodiments described in this, and other sections are intended to be applicable to all embodiments and aspects of the present application herein described for which they are suitable as would be understood by a personskilled in the art. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0038] In understanding the scope of the present application, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and / or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. The term “consisting” and its derivatives, as used herein, are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, but exclude the presence of other unstated features, elements, components, groups, integers and / or steps. The term “consisting essentially of’, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and / or steps as well as those that do not materially affect the basic and novel characteristic(s) of features, elements, components, groups, integers, and / or steps.

[0039] Terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. In addition, all ranges given herein include the end of the ranges and also any intermediate range points, whether explicitly stated or not.

[0040] As used in this application, the singular forms “a”, “an” and “the” include plural references unless the content clearly dictates otherwise.

[0041] In embodiments comprising an “additional” or “second” component, the second component as used herein is different from the other components or first component. A “third” component is different from the other, first, and second components, and further enumerated or “additional” components are similarly different.

[0042] The term “and / or” as used herein means that the listed items are present, or used, individually or in combination. In effect, this term means that “at least one of’ or “one or more” of the listed items is used or present.

[0043] The abbreviation, “e.g.” is derived from the Latin exempli gratia and is used herein to indicate a non-limiting example. Thus, the abbreviation “e.g.” is synonymous with the term “for example.” The word “or” is intended to include “and” unless the context clearly indicates otherwise.

[0044] The term “hydroborane” as used herein refers to a borane with at least one hydrogen substituent directly bound to boron, and may exist as a monomer or a dimer, such as but not limited to HB(OCMe2CMe2O), (HB'Pr2)2 or B2H6. The term “base-free hydroborane” as used herein is used to specifically refer to a hydroborane that is not a hydroborane-Lewis base adduct, and unless otherwise specified, a hydroborane refers to a base-free hydroborane. The term “hydroborane-Lewis base adduct” as used herein refers to a hydroborane that is coordinated to an external Lewis base; examples include H3B(NMe3), H3B(NHMe2), H3B(PMe3), and H3B(SMe2).

[0045] The term “hydrosilane” as used herein refers to a silane with at least one hydrogen substituent directly bound to silicon, such as but not limited to SiFL, H3SiPh, H3Si"Bu, H2SiEt2, HSiMe3, HSiClMe2, H2SiCl2, or H3SiCl.

[0046] The term “hydrostannane” as used herein refers to a tin compound with at least one hydrogen substituent directly bound to tin, such as but not limited to HSn"Bu3.

[0047] The term “hydroalane” as used herein refers to an alane with at least one hydrogen substituent directly bound to aluminium, which may exist as a monomer or a dimer, for example ('BmAIHL. A hydroalane-Lewis base adduct refers to a hydroalane that is coordinated to an external Lewis base, such as H3Al(quinuclidine).

[0048] The term “alkyl” as used herein, whether it is used alone or as part of another group, means straight or branched chain, saturated alkyl groups. The number of carbon atoms that are possible in the referenced alkyl group are indicated by the numerical prefix “Cni-n2”. For example, the term Ci-3alkyl means an alkyl group having 1, 2 or 3 carbon atoms.

[0049] The term “cycloalkyl” as used herein, whether it is used alone or as part of another group, means a mono- or bicyclic, saturated cycloalkyl group. The number of carbon atoms that are possible in the referenced cycloalkyl group are indicated by the numerical prefix “Cni-n2”. For example, the term C3.5cycloalkyl means a cycloalkyl group having 3, 4 or 5 carbon atoms. When a cycloalkyl group contains more than one cyclic structure or rings, the cyclic structures may be fused, bridged, spiro connected or linked by a single bond. The term “fused” as used herein in reference to a first cyclic structure being “fused” with a second cyclic structure meansthe first cyclic structure and the second cyclic structure share at least two adjacent atoms therebetween. The term “bridged” as used herein in reference to a first cyclic structure being “bridged” with a second cyclic structure means the first cyclic structure and the second cyclic structure share at least two non-adjacent atoms therebetween. The term “spiro-connected” in reference to a first cyclic structure being “spiro connected” with a second cyclic structure means the first cyclic structure and the second cyclic structure share one atom therebetween.

[0050] The term “available”, as used herein in reference to “available hydrogen atoms” and “available carbon atoms” and the like refers to atoms that would be known to a person skilled in the art to be capable of modification and / or replacement by another atom or substituent. A person skilled in the art would also readily appreciate that this would not encompass structures of base-free hydroboranes or germanium-containing precursor compounds and the like that would not, for example be suitable for use in the processes of the present application. For example, in the case of one or more available carbon atom(s) being replaced by silicon atom(s) the carbon being replaced would typically be a tertiary carbon atom.

[0051] The skilled person would appreciate that the term “precursor” as used herein may refer to a molecule that may be used for film deposition. The term “co-reactant” may also be used to refer to a precursor, and herein, the terms precursor and co-reactant may be used interchangeably depending on the context in which they are used.

[0052] The term “elemental germanium” as used herein refers to germanium in the zero oxidation sate.

[0053] The terms “germanium complex” or “germanium compound” refer to a molecule which contains germanium bound to one or more ligands. The term “ligand” refers to a chemical species that is bound to a metal or semimetal; examples of ligands are alkoxide ligands (singly deprotonated alcohols), amido ligands (singly deprotonated non-tertiary amines), acetylacetonate ligands (MeCOCHCOMe ). chloride ligands (Cl ). and hydride ligands (H_).

[0054] As used herein, Me is methyl, Et is ethyl, 'Pr is isopropyl, "Pr is / 7-propyl. 'Bu is isobutyl, "Bu is / 7-butyl. 'Bu is sec-butyl, 'Bu is tert-butyl, "Pent is / 7-pentyl. Cyp is cyclopentyl, 1-Norb is 1-norbomyl, pin is pinacolate (OCMe2CMe2O), cat is ort / zo-catecholate (prtho- O2C6H4), HBpin is HB(OCMe2CMe2O), HBcat is HB(ort / 2o-O2C6H4), 9-BBN is 9- borabicyclo[3.3.1]nonane, PTFE is polytetrafluoroethylene) {(CF2CF2)n'}, XRD is X-ray diffraction, VASE is Variable Angle Spectroscopic Ellipsometry, XPS is X-ray PhotoelectronSpectroscopy, AFM is Atomic Force Microscopy, SEM is Scanning Electron Microscopy, FESEM is Field Emission Scanning Electron Microscopy, GPC is Growth rate Per Cycle (typically in units of A), ppb is parts per billion, SiO Si refers to a silicon wafer with a layer of SiCE at the surface, and hydrogen-terminated silicon, or hydrogen-terminated Si, or FI- terminated silicon, or H-terminated Si, or H-Si refers to a hydrogen-terminated silicon wafer.

[0055] One of ordinary skill in the art will recognize that the terms “film” or “layer” used herein may refer to a thickness of some material distributed on a surface, and that the surface may be planar or patterned (e.g. with trenches or vias, or more complex structures), or naturally non-planar as in the case of particles, nanotubes, fibres, aerogels or cloths.

[0056] It will be understood that any component defined herein as being included may be explicitly excluded by way of proviso or negative limitation, such as any specific compounds or process steps, whether implicitly or explicitly defined herein.II, Processes and Uses Thereof

[0057] The present application includes a process for depositing a material comprising elemental germanium, the process comprising a deposition cycle comprising: exposing a heated substrate to a vapor comprising a germanium-containing precursor compound; and exposing the heated substrate to a vapor comprising a co-reactant selected from a base-free hydroborane, a hydrosilane, a hydrostannane and a hydroalane.

[0058] The co-reactant can comprise any suitable co-reactant selected from a base-free hydroborane, a hydrosilane, a hydrostannane and a hydroalane, the selection of which can be made by a person skilled in the art having regard to the present disclosure.

[0059] In an embodiment, the co-reactant comprises a base-free hydroborane. In an embodiment, the co-reactant comprises a hydrosilane. In an embodiment, the co-reactant comprises a hydrostannane. In an embodiment, the co-reactant comprises a hydroalane.

[0060] The base-free hydroborane can be any suitable base-free hydroborane or combinations thereof, the selection of which can be made by a person skilled in the art having regard to the present disclosure.

[0061] In an embodiment, the base-free hydroborane is selected from:(i) HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from H and Ci-4alkyl;(ii) HB(OCR2aR2bCR2cR2dCR2eR2fO), wherein R2a, R2b, R2°, R2d, R2eand R2fare each independently selected from H and Ci-4alkyl;(iii) HBcat;(iv) (9-BBN)n, wherein n is 1 or 2;(v) (HBR32)m, wherein m is 1 or 2, each R3is independently selected from Ci-salkyl and Cs-scycloalkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom; and(vi) B2H6.

[0062] In another embodiment, the base-free hydroborane is selected from:(i) HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from H and Ci-4alkyl;(ii) HB(OCR2aR2bCR2cR2dCR2eR2fO), wherein R2a, R2b, R2°, R2d, R2eand R2fare each independently selected from H and Ci-4alkyl;(iii) HBcat;(iv) (9-BBN)n, wherein n is 1 or 2; and(v) (HBR32)m, wherein m is 1 or 2, each R3is independently selected from Ci-salkyl and Cs-scycloalkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom.

[0063] In an embodiment, n is 1. In another embodiment, n is 2.

[0064] In an embodiment, m is 1. In another embodiment, m is 2.

[0065] In an embodiment, R3is independently selected from Ci-salkyl, cyclopentyl, andCH2SiMe3. In another embodiment, Rla, Rlb, Rlc, Rld, R2aR2b, R2c, R2d, R2eand R2fare independently selected from H, Me, Et, "Pr and 'Pr; and R3is independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu, Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2Bu. CH2 / BU, CH2SiMe3, and cyclopentyl, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe / Bu. and CMe2CH2Bu.

[0066] In another embodiment, the base-free hydroborane is HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from H and Ci-4alkyl. In another embodiment, the base-free hydroborane is HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from H, Me, Et, "Pr and 'Pr. In a furtherembodiment, the base-free hydroborane is HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from Ci-3alkyl.

[0067] In another embodiment, the base-free hydroborane is pinacolborane (HBpin).

[0068] The hydrosilane can be any suitable hydrosilane or combinations thereof, the selection of which can be made by a person skilled in the art having regard to the present disclosure. In an embodiment, the hydrosilane is selected from SiH(R13)3 and HsSiR14, wherein each R13is independently selected from H, chloro -O-Ci-4alkyl, Ci-salkyl and C3- scycloalkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom; and R14is phenyl, optionally substituted with one or more substituents selected from Cnsalkyl or methoxy, and wherein one or more available hydrogen atoms in the phenyl and / or Ci-salkyl are optionally replaced with fluorine. In an embodiment, the hydrosilane is selected from SiH(R13)3 and FESiR14, wherein each R13is independently selected from H, chloro -O-Ci-4alkyl, Ci-salkyl, cyclopentyl and CF SiMes; and R14is an aryl substituent selected from phenyl, C^FEMe. CeFUEt, CeH4"Pr, CeFU'Pr, CEFEMe?. CeF Mes, C6H4(OMe), C6H3(OMe)2, C6H4(CF3), C6H4F, C6H3F2, C6H2F3, C6HF4, and C6F5. In another embodiment, the hydrosilane is selected from SiFU, FESiR13a, H2SiR13aR13b, HSiR13aR13bR13c, or H3SiR13d, wherein R13a, R13band R13care independently selected from Cl, OMe, OEt, O"Pr, O Pr. O"Bu, O'Bu. O'Bu. O'Bu. Me, Et, "Pr, 'Pr, "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH Bu, CH2'Bu. CH2SiMe3, and cyclopentyl, and R14is an aryl substituent selected from Ph, CeFUMe, CeFUEt, CeFE'Er. CeFU'Pr, CgFEMe^ CeH2Me3, C6H4(OMe), C6H3(OMe)2, C6H4(CF3), C6H4F, C6H3F2, C6H2F3, C6HF4, or C6F5.

[0069] The hydrostannane can be any suitable hydrostannane or combinations thereof, the selection of which can be made by a person skilled in the art having regard to the present disclosure. In an embodiment, the hydrostannane is HSnR15aR15bR15c, wherein R15a, R15band R15Care each independently selected from Ci-salkyl and Cs-scycloalkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom. In another embodiment, the hydrostannane is HSnR15aR15bR15c, wherein R15a, R15band R15care each independently selected from Ci-salkyl, cyclopentyl and CH2SiMe3. In another embodiment, the hydrostannane is HSnR15aR15bR15c, wherein R15a, R15band R15care independently selected from Me, Et, "Pr, Tr, "Bu, 'Bu, Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'BU, CH2BU. CFE'Bu. CH2SiMe3, and cyclopentyl.

[0070] The hydroalane can be any suitable hydroalane, the selection of which can be made by a person skilled in the art having regard to the present disclosure. In an embodiment, the hydroalane is (HAlR16aR16b)p, wherein p is 1 or 2, and R16aand R16bare each independently selected from Ci-salkyl. In another embodiment, the hydroalane is (HAlR16aR16b)p, wherein p is 1 or 2, and R16aand R16bare independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu. Bu. 'Bu. CHMe"Pr, CHMe'Pr. CHEt2, CMe2Et, CMe 'Pr. CMe2'Pr. CMe 'Bu. CMe2'Bu. CMe Bu, and CMe2CH2 / Bu. In an embodiment, p is 1. In another embodiment, p is 2.

[0071] The germanium-containing precursor compound can be any suitable germanium- containing precursor compound or combinations thereof, the selection of which can be made by a person skilled in the art having regard to the present disclosure. In an embodiment, the germanium-containing precursor compound contains germanium bound exclusively to oxygen, nitrogen and / or chlorine atoms. In another embodiment, the germanium-containing precursor compound contains germanium bound exclusively to oxygen and / or nitrogen atoms. In another embodiment, the germanium-containing precursor compound is a germanium(IV) or germanium(II) alkoxide or amide compound, where one substituent of the alkoxide or amide group optionally contains an additional ether or amine donor. In an embodiment, the germanium-containing precursor compound is selected from:(i) Ge(OR4)4, wherein each R4is independently selected from Ci-salkyl and C3- 7cycloalkyl and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom;(ii) Ge(NR5R6)4, wherein each R5and R6are independently selected from Ci- salkyl and C3-7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom;(iii) Ge(OR7)2, wherein each R7is independently selected from Ci-salkyl, C3- 7cycloalkyl, CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b, CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b, CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7b, wherein each R7ais independently selected from H and Ci-3alkyl, each R7bis independently selected from Ci-3alkyl, and one or more available carbon atoms in the Cj -5 alky I is / are optionally replaced by a silicon atom;(iii) Ge(NR8R9)2, wherein each R8is independently selected from Ci-salkyl and C3- 7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / areoptionally replaced by a silicon atom; and each R9is independently selected from Ci.5alkyl, C3-7cycloalkyl, CR9aR9aCH2NR9bR9b, CR9aR9aCH2CH2NR9bR9b, CH2CR9aR9aCH2NR9bR9b, CR9aR9aCH2OR9b, CR9aR9aCH2CH2OR9b, and CH2CR9aR9aCH2OR9b, wherein each R9ais independently selected from H and Ci-3alkyl, each R9bis independently selected from Ci-3alkyl, and one or more available carbon atoms in the Ci- salkyl is / are optionally replaced by a silicon atom; and(iv) Ge{N(SiR10R11R12)2}2, wherein each R10, R11and R12is independently selected from Ci-3alkyl.

[0072] In an embodiment, the germanium-containing precursor compound is Ge(OR4)4, wherein each R4is independently selected from Cj-salk l and C3-?cycloalkyl and one or more available carbon atoms in the Cj-salk l is / are optionally replaced by a silicon atom. In another embodiment, the germanium-containing precursor compound is Ge(OR4)4, wherein each R4is independently selected from Ci-salk l. cyclopentyl, 1-norbomyl and CH2SiMe3. In another embodiment, the germanium-containing precursor compound is Ge(OR4)4, wherein each R4is independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, CH2'BU. CH2BU. CH2'BU. CH2SiMe3, cyclopentyl and 1-norbomyl.

[0073] In an embodiment, the germanium-containing precursor compound is Ge(NR5R6)4, wherein each R5and R6are independently selected from Ci-salkyl and C3- 7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom. In another embodiment, the germanium-containing precursor compound is Ge(NR5R6)4, wherein each R5and R6are independently selected from Ci- salkyl, cyclopentyl, 1-norbomyl and CH2SiMe3. In another embodiment, the germanium- containing precursor compound is Ge(NR5R6)4, wherein each R5and R6are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu. 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'BU, CH2BU. CH2'BU. CH2SiMe3, cyclopentyl and 1-norbomyl.

[0074] In an embodiment, the germanium-containing precursor compound is Ge(OR7)2, wherein each R7is independently selected from Ci-salkyl, C3-7cycloalkyl, CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b, CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b, CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7b, wherein each R7ais independently selected from H and Ci-3alkyl, each R7bis independently selected from Ci- salkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced bya silicon atom. In another embodiment, the germanium-containing precursor compound is Ge(OR7)2, wherein each R7is independently selected from Ci-salkyl, cyclopentyl, 1- norbomyl, CH2SiMe3, CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b, CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b, CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7b, wherein each R7ais independently selected from H and Ci-3alkyl and each R7bis independently selected from Ci-3alkyl. In another embodiment, the germanium- containing precursor compound is Ge(OR7)2, wherein each R7is independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, CH2'Bu. CHfBu. CH2'BU. CH2SiMe3, cyclopentyl, 1-norbomyl, CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b, CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b,CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7bwherein each R7ais independently selected from H, Me, Et, "Pr and 'Pr and each R7bis independently selected from Me, Et, "Pr, and 'Pr.

[0075] In an embodiment, the germanium-containing precursor compound is Ge(OR7)2, wherein each R7is independently CR7aR7aCH2NR7bR7b, wherein each R7ais independently selected from H and Ci-3alkyl and each R7bis independently selected from Ci-3alkyl. In another embodiment, the germanium-containing precursor compound is Ge(OR7)2, wherein each R7is independently CR7aR7aCH2NR7bR7b, wherein each R7ais independently selected from H, Me, Et, "Pr and 'Pr and each R7bis independently selected from Me, Et, "Pr, and 'Pr. In another embodiment, the germanium-containing precursor compound is Ge(OCH2CH2NMe2)2. In another embodiment, the germanium-containing precursor compound is Ge(OCMe2CH2NMe2)2.

[0076] In an embodiment, the germanium-containing precursor compound is Ge(NR8R9)2or Ge {N(SiRl 0R" Rl 2)2l2.

[0077] In an embodiment, the germanium-containing precursor compound is Ge(NR8R9)2, wherein each R8is independently selected from Cj-salk l and C3.7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom; and each R9is independently selected from Ci-salkyl, C3.7cycloalkyl, CR9aR9aCH2NR9bR9b, CR9aR9aCH2CH2NR9bR9b, CH2CR9aR9aCH2NR9bR9b, CR9aR9aCH2OR9b, CR9aR9aCH2CH2OR9b, and CH2CR9aR9aCH2OR9b, wherein each R9ais independently selected from H and Ci-3alkyl, each R9bis independently selected from Ci-3alkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom. In an embodiment, the germanium- containing precursor compound is Ge(NR8R9)2, wherein each R8is independently selected from selected from Cj-salk l. cyclopentyl, 1-norbomyl and CH2SiMe3; and each R9is independentlyselected from Cj-salkyl. cyclopentyl, 1-norbomyl and CH2SiMe3, CR9aR9aCH2NR9bR9b, CR9aR9aCH2CH2NR9bR9b, CH2CR9aR9aCH2NR9bR9b, CR9aR9aCH2OR9b, CR9aR9aCH2CH2OR9b, and CH2CR9aR9aCH2OR9b, wherein each R9ais independently selected from H and Ci-3alkyl, each R9bis independently selected from Ci-3alkyl. In an embodiment, the germanium- containing precursor compound is Ge(NR8R9)2, wherein each R8is independently selected from Me, Et, "Pr, Tr, "Bu. 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, CH2'Bu. CH Bu, CH2'BU. CH2SiMe3, cyclopentyl and 1-norbomyl; and each R9is independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CHf Bu. CH Bu, CH2SiMe3, cyclopentyl, 1-norbomyl, CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b. CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b, CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7bwherein each R7ais independently selected from H, Me, Et, "Pr and 'Pr and each R7bis independently selected from Me, Et, "Pr, and 'Pr.

[0078] In an embodiment, the germanium-containing precursor compound is Ge{N(SiR10RnR12)2}2, wherein each R10, R11and R12is independently selected from Cmalkyl. In another embodiment, the germanium-containing precursor compound is Ge{N(SiR10R11R12)2}2, wherein each R10, R11and R12is independently selected from Me, Et, "Pr, and Pr.

[0079] In an embodiment, the material is in the form of a film. In an embodiment, the process further comprises repeating the deposition cycle until a material (e.g., a film) of a desired thickness is deposited. In an embodiment, the process comprises from 2 to 6000 deposition cycles, from 5 to 4000 deposition cycles, or from 10 to 2000 deposition cycles.

[0080] In an embodiment, the film has an average thickness of less than 300 nm or less than 100 nm or less than 50 nm or less than 20 nm or less than 10 nm.

[0081] In an embodiment, the vapor comprising a germanium-containing precursor compound and the vapor comprising a co-reactant are introduced with the assistance of the flow of an inert gas such as N2, He or Ar. The vapor comprising the germanium-containing precursor compound and the vapor comprising the co-reactant are introduced using any suitable pulse time. Pulse times may depend, for example, on the properties of the the germanium-containing precursor compound and / or the co-reactant, the chemical nature of the substrate, the design of the deposition reactor, and / or the geometric shape of the surface(s) of the substrate but could be readily selected by a person skilled in the art having regard to the present disclosure. For example, thin film growth on flat surfaces enables shorter pulse times, whereas film growth on three-dimensional surfaces can require much longer pulse times.Therefore, in an embodiment, pulse times are each independently from about 0.005 to about 300 seconds. In another embodiment, pulse times are from about 0.005 to about 30 seconds.

[0082] In an embodiment, subsequent to exposing to the vapor comprising the germanium-containing compound, the process further comprises: purging with a purge gas to remove at least a portion of excess germanium- containing precursor compound and / or byproducts.

[0083] In an embodiment, subsequent to exposing to the vapor comprising the coreactant, the process further comprises: purging with a purge gas to remove at least a portion of excess co-reactant and / or byproducts.

[0084] The person skilled in the art would appreciate that the purge gas can be any suitable gas or combination thereof and is typically an inert gas such as such as N2, He or Ar.

[0085] Purge times are any suitable values and may also depend, for example, on the properties of the the germanium-containing precursor compound and / or the co-reactant, the chemical nature of the substrate, the design of the deposition reactor, and / or the geometric shape of the surface(s) of the substrate but could be readily selected by a person skilled in the art having regard to the present disclosure. For example, thin film growth on flat surfaces enables shorter purge times, whereas film growth on three-dimensional surfaces can require much longer purge times. Therefore, in an embodiment, purge times are each independently from about 0.005 to about 300 seconds. In another embodiment, purge times are from about 2 to about 200 seconds.

[0086] In an embodiment, the process comprises an atomic layer deposition (ALD) process. In another embodiment, the process comprises a thermal ALD process.

[0087] The substrate can be any suitable substrate. The term “substrate” refers to a material or materials on which a deposition process is conducted (excluding the inner surfaces of the deposition reactor), and in one embodiment, the substrate may refer to a wafer, such as a wafer suitable for semiconductor or photonic device manufacturing. The substrate may have one or more layers of differing materials already deposited upon it from a previous manufacturing step. For example, substrates may include silicon layers (e.g., crystalline, amorphous, porous, H-terminated silicon, etc.), silicon containing layers (e.g., SiC>2, SiN, SiON, SiCOH, etc.), elemental metal containing layers (e.g., titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten,manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, aluminium, etc.) or combinations thereof, or elemental semimetal or nonmetal containing layers (e.g. boron, indium, black phosphorus, antimony, bismuth, tellurium, etc.). The substrate may include a polymer layer, a region with an organic monolayer on the surface, or an organic patterned photoresist film. The substrate may include one or more layers of oxides, such as those used as dielectric materials (e.g. materials based on TiCh, ZrCh. HfO2. Ta20s, SiCh, GeCh, AI2O3, rare earth oxide-based materials, ternary oxide-based materials, etc.) or nitride-based films (e.g. TiN, TaN, NbN or Si2Ns, etc.), or other materials including carbides, silicides, germanides, sulfides, selenides, tellurides, phosphides, arsenides, antimonides, and fluorides.

[0088] In an embodiment, the heated substrate comprises H-terminated silicon.

[0089] In an embodiment, the film growth rate is greater than 0. 1 A / cycle. In another embodiment, the film growth rate is greater than 0.2 A / deposition cycle.

[0090] In an embodiment, the germanium content of the film is greater than or equal to about 80 at%, about 85 at% or about 90 at% within the bulk portion of the film, with the remainder of the content of the film comprising impurities.

[0091] In an embodiment, the heated substrate comprises a target surface material and a non-target surface material, and wherein the film comprising elemental germanium is deposited on the target surface material at a higher film growth rate than the non-target surface material. In some embodiments the selectivity (the ratio of film growth rate on a target surface material to the film growth rate on a non-target surface material) is greater than 2, such as greater than 5, or greater than 10. In another embodiment, the non-target material comprises a dielectric material. In another embodiment, the target surface material comprises H-terminated silicon and the non-target surface material comprises silicon oxide, germanium oxide, aluminum oxide, a rare earth metal oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, indium tin oxide or combinations thereof. In another embodiment, the non-target surface material comprises silicon oxide.

[0092] The heated substrate is at any suitable temperature which may depend, for example, on the identity of the germanium-containing precursor compound and / or the identity of the co-reactant. In an embodiment, the temperature of the heated substrate (i.e. the deposition temperature) is between 20 °C and 500 °C, for example between 100 °C and 400 °C.

[0093] The process may be carried out in any suitable deposition reactor, the selection of which can be made by a person skilled in the art with reference to the present disclosure.

[0094] The pressure in the reactor during deposition is set any suitable value which may depend, for example, on the properties of the germanium-containing precursor compound and / or the co-reactant and / or the film to be formed. In an embodiment, the pressure is from about 106Torr to about 760 Torr. In another embodiment, the pressure is from about 0.1 mTorr to about 10 Torr. In another embodiment, the pressure is from about 10 mTorr to about 10 Torr. In a further embodiment, the pressure is from about 100 mTorr to about 2 Torr.

[0095] The present disclosure also includes an electronic device, memory or logic device, photonic device or quantum device comprising a film comprising elemental germanium deposited by a process as described herein.

[0096] The present disclosure also includes a process for preparing a binary, ternary or quaternary material, a doped material, or a nanolaminate, the process comprising: depositing a film comprising elemental germanium by a process as described herein; and one or more additional film deposition processes.

[0097] The present disclosure also includes use of a process as described herein in the fabrication of an electronic device, memory or logic device, photonic device or quantum device.

[0098] This application also discloses a cyclic film deposition process that results in the deposition of a film comprising elemental germanium, with each cycle comprising sequentially contacting a heated substrate with vapours of a germanium-containing compound (precursor- A), and contacting the substrate with vapours of a second precursor (precursor-B) selected from a base-free hydroborane, a hydrosilane, a hydrostannane, or a hydroalane.

[0099] In one embodiment, the germanium-containing compound (precursor- A) contains germanium bound exclusively to oxygen, nitrogen and / or chlorine atoms. In one refinement, the germanium-containing compound (precursor-A) contains germanium bound exclusively to oxygen and / or nitrogen atoms. In another refinement, precursor-A is a germanium(IV) or germanium(II) alkoxide or amide compound, where one substituent of the alkoxide or amide group may contain an additional ether or amine donor. More specifically, precursor-A is typically selected from Ge(ORr)4, Ge(NR2R3)4, Ge(OR4)2, Ge(NR5R6)2, or GeN(SiR7R8R9)2 wherein R1, R2, R3' and R5are independently selected from Me, Et, "Pr,'Pr, "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, CH2'Bu. CH2BU. CH2'BU. CH2SiMe3, cyclopentyl, and 1-norbomyl, and R4and R6are independently selected from Me, Et, "Pr,;Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2Bu. CH2'Bu, CH2SiMe3, cyclopentyl, 1-norbomyl, CR^R^'CH^R^R13', CR10R11'CH2CH2NR12R13', CftCR^'R^'CftNR^'R13', CR10'R11'CH2OR12', CR10'R11'CH2CH2OR12', andCH2CR10RnCH2OR12wherein R10' and R11are independently selected from H, Me, Et, "Pr and 'Pr and R12and R13are independently selected from Me, Et, "Pr, and 'Pr, and R7, R8and R9' are independently selected from Me, Et, "Pr, and 'Pr. A preferred composition of precursor-A is Ge(OR4)2, most ideally Ge(OCR10RnCH2NR12R13)2with the R-groups selected from those specified in this paragraph.

[0100] Precursor-B in this film deposition process is selected from (a) a base-free hydroborane selected from HB(OCR1R2'CR3R4'O), HB(OCR1'R2'CR3'R4'CR5'R6'O), HBcat, (9-BBN)n', (HBR72)»', or B2He, wherein n' is 1 or 2, the substituents R1, R2, R3, R4, R5and R6' are independently selected from H, Me, Et, "Pr 'Pr, "Bu, 'Bu, "Bu and 'Bu, and R7is independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'BU, CH2"BU, CH2'BU, CH2SiMe3, and cyclopentyl, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2"Bu, and CMe2CH2'Bu, (b) a hydrosilane selected from SiH4, HsSiR1, H2SiR? R2, HSiR1R2R3, or H3SiR4, wherein R1', R2and R3are independently selected from Cl, OMe, OEt, O"Pr, O'Pr, O"Bu, O'Bu, O"Bu, O'Bu, Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2"BU, CH2'BU, CH2SiMe3, and cyclopentyl, and R4is an aryl substituent selected from Ph, C6H4Me, C6H4Et, C6H4"Pr, C6H4'Pr, C6H3Me2, and C6H2Me3, C6H4(OMe), C6H3(OMe)2, C6H4(CF3), CeH4F, CeH3F2, CeH2F3, CeHF4, or CeFs, (c) a hydrostannane with the formula HSnR1R2R3, wherein R1, R2and R3are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2"Bu, CH2'Bu, CH2SiMe3, and cyclopentyl, or (d) a hydroalane with the formula (HAIR1R2), , wherein n' is 1 or 2, and R1and R2are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2"Bu, and CMe2CH2'Bu. A preferred composition of precursor-B is a hydroborane selected from HB(OCR1'R2'CR3'R4'O), HB(OCR1'R2'CR3'R4'CR5'R6'O), HBcat, (9-BBN)„', (HBR7'2)„', or B2Hg, with R-groups selected from those defined in this paragraph.

[0101] In an embodiment, the process may be carried out with the use of a purge gas to remove at least a portion of excess vapour phase precursor- A, and reaction byproducts if any, from the reaction space after contacting the substrate with precursor-A and before contacting the surface with precursor-B, and the use of a purge gas to remove at least a portion of excess precursor-B, and reaction byproducts if any, from the reaction space after contacting the substrate with precursor-B and before contacting the surface with precursor-A.

[0102] The fdm deposition process disclosed in this application may be an atomic layer deposition (ALD) process, where self-limiting growth is achieved, or may be a chemical vapour deposition process, where self-limiting growth is not achieved.

[0103] The germanium-containing fdms resulting from the deposition process disclosed in this application may be comprised of elemental germanium, and in some embodiments, the germanium content of the fdm is greater than or equal to about 80 at%, 85 at%, 90 at%, 95 at%, 98 at%, 99 at% or 99.5 at% within the bulk portion of the fdm.

[0104] In typical embodiments, the deposition is carried out without addition of hydrogen gas. In some embodiments, the deposition process may be carried out in the presence of a continuous or periodic flow of hydrogen or a mixture of hydrogen in an inert gas. In such embodiments, a continuous flow of hydrogen is for use with precursor combinations (e.g. combinations of precursor-A and precursor-B) where neither precursor on its own reacts appreciably with H2 under the conditions of the deposition experiment.

[0105] The current application also discloses use of a deposition reactor with sources to provide vapours of each precursor (e.g. precursor-A and precursor-B) to the reaction chamber during the thin fdm deposition process. For a precursor that would be a gas at room temperature and atmospheric pressure, the source typically comprises a pressurized gas cylinder (containing the precursor or a mixture of the precursor and one or more compatible gasses such as N2, He or Ar) that is connected to a device (e.g. a gas regulator) to control the pressure of the gas in the delivery line to the reactor, a mass flow controller to control the gas flow rate, and a valve that prevents the flow of gas into the deposition chamber of the reactor when the valve is closed, and allows passage of the gas into the deposition chamber when the valve is opened. For a solid or liquid precursor, the source may comprise a vessel (e.g. a metal cylinder or a glass vessel) that is connected to a valve which prevents escape of the precursor vapours when the valve is closed and allows passage of the precursor vapours into the deposition chamber of the reactor when the valve is opened. Herein, this design of source vessel may be referred to as anon-flow-through design. In one refinement, the source may be a vessel having an inlet and an outlet tube to allow an inert gas to flow through the vessel during each pulse of the precursor. This inert gas flow is controlled by valves (valves A and B) on the inlet and outlet tubes to / from the vessel, and a valve (valve C) on the delivery line between the connection points to the inlet and outlet tubes to / from the vessel. When the precursor is not in use, valves A and B are closed, and valve C is open, so that inert gas can flow through the delivery line into the reaction chamber, but precursor vapours cannot exit the source. To deliver a pulse of precursor vapour into the reactor, valves A and B are opened, and valve C is closed, so that the inert gas flowing into the delivery line is required to flow through the source en route to the reaction chamber. Herein, this design of source vessel may be referred to as a flow-through design.

[0106] The pressure during film deposition is set at a value suitable to the properties of the chemical precursors and film to be formed. In one refinement, the pressure is from about 106Torr to about 760 Torr. In another refinement, the pressure is from about 0.1 mTorr to about 10 Torr. In another refinement, the pressure is from about 10 mTorr to about 10 Torr. In a further refinement, the pressure is from about 100 mTorr to about 2 Torr.

[0107] Pulse times and purge times also depend on the properties of the chemical precursors, the chemical nature of the substrate surface, the design of the deposition reactor, and the geometric shape of the substrate(s). Thin film growth on flat substrates enables shorter pulse and purge times, whereas film growth on 3-dimensional substrates can require much longer pulse and purge times. Therefore, in one refinement, pulse times and purge times are each independently from about 0.005 to 300 seconds. In another refinement, pulse times are from about 0.005 to 30 seconds, and purge times are from about 2 to 200 seconds.

[0108] The deposition process disclosed herein typically involves between 1 and 6000 deposition cycles, or from 5 to 4000 deposition cycles, or 10 to 2000 deposition cycles. The deposition process disclosed herein is typically carried out with a substrate temperature (i.e. a deposition temperature) between 20 and 500 °C, most typically between 100 and 400 °C.

[0109] In some embodiments, films comprising germanium are deposited selectively on one material relative to another material. The term “selective deposition” as used herein refers to deposition on a target surface material at a higher rate than on a non-target surface material. In some embodiments the selectivity (the ratio of film growth rate on a target surface material to the film growth rate on a non-target surface material) is greater than 2, such as greater than 5, or greater than 10. In some embodiments, films comprising elemental germanium aredeposited on H-terminated silicon without being substantially deposited on dielectric surfaces, such as silicon oxide, germanium oxide, aluminum oxide, a rare earth metal oxide, titanium oxide, zirconium oxide, hafnium oxide, or tantalum oxide.

[0110] The deposition process disclosed herein may be interspersed with one or more other film deposition process for the purpose of fabricating a binary, ternary or quaternary material, or a nanolaminate. The deposition process disclosed herein may be used for any number of applications, including electronic device fabrication, memory or logic device fabrication, photonic device fabrication, or quantum device fabrication.

[0111] Also provided herein is a process for deposition of a film comprising elemental germanium, the process comprising one or more deposition cycles, each cycle comprising sequentially contacting a heated substrate with vapours of a germanium-containing compound (precursor-A), and contacting the substrate with vapours of a second precursor (precursor-B) selected from a base-free hydroborane, a hydrosilane, a hydrostannane, or a hydroalane. In an embodiment, the germanium-containing compound (precursor-A) exclusively contains germanium-oxygen bonds, germanium-nitrogen bonds, germanium-chlorine bonds, or a mixture of these types of bonds. In another embodiment, the germanium-containing compound (precursor-A) exclusively contains germanium-oxygen bonds, germanium-nitrogen bonds, or a mixture of these types of bonds. In an embodiment, the germanium-containing compound (precursor-A) is a germanium alkoxide or amide compound selected from Ge(ORr)4, Ge(NR2R3)4, Ge(OR4)2, Ge(NR5R6)2, or Ge{N(SiR7R8R9)2}2 wherein R1, R2, R3and R5are independently selected from Me, Et, "Pr, 'Pr. "Bu, 'Bu. Bu. 'Bu. "Pent, CHMe"Pr, CHMe'Pr. CHEt2, C E'Bu. CFE'Bu. CFE'Bu. CEESiMes, cyclopentyl, and 1-norbomyl, and R4and R6are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu. 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'BU, CFE'Bu. CH2 / BU, CFESiMes. cyclopentyl, 1-norbomyl, CR10'R11'CH2NR12'R13', CR1O'R11'CH2CH2NR12'R13', CH2CR1O'R11'CH2NR12'R13',CR10'R11'CH2OR12', CR10'R11'CH2CH20R12', and CH2CR10R11'CH2OR12' wherein R10' and R11are independently selected from H, Me, Et, "Pr and 'Pr and R12and R13are independently selected from Me, Et, "Pr, and 'Pr, and R7, R8and R9are independently selected from Me, Et, "Pr, and 'Pr. In an embodiment, the germanium-containing compound (precursor-A) is Ge(ORr)4. In an embodiment, the germanium-containing compound (precursor-A) is Ge(NR2R3)4. In an embodiment, the germanium-containing compound (precursor-A) is Ge(OR4')2. In an embodiment, the germanium-containing compound (precursor-A) isGe(NR5R6')2 or Ge{N(SiR7R8R9)2}2. In an embodiment, precursor-B is a base-free hydroborane selected fromHB OCR^ CR^O), HB(OCR1R2'CR3'R4'CR5R6'O), HBcat, (9- BBN),,-. (HBR7'2)„', or B2H6, wherein n' is 1 or 2, the substituents R1, R2, R3, R4, R5and R6are independently selected from H, Me, Et, "Pr, 'Pr, "Bu, 'Bu. Bu and 'Bu. and R7is independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, Bu. 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'BU, CH2BU. CH2'BU, CH2SiMe3, and cyclopentyl, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2'Bu. and CMe2CH2'Bu. In an embodiment, precursor-B is a hydrosilane selected from SiH4, H3SiRr, H2SiRrR2, HSiR1R2R3, or FFSiR4. wherein R1, R2and R3are independently selected from Cl, OMe, OEt, O"Pr, O'Pr, O"Bu, O'Bu, O'Bu. O'Bu, Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CFE'Bu. CFE'Bu. CH2SiMe3, and cyclopentyl, and R4is an aryl substituent selected from Ph, CEFUMe. CEFEEt. CeHfTr, CEFE'Pr. CeH3Me2, and CeH2Me3, C6H4(OMe), C6H3(OMe)2, C6H4(CF3), C6H4F, C6H3F2, C6H2F3, C6HF4, or C6F5. In an embodiment, precursor-B is a hydrostannane with the formula HSnR1R2R3, wherein R1', R2' and R3are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2"Bu, CFE'Bu. CH2SiMe3, and cyclopentyl. In an embodiment, precursor-B is a hydroalane with the formula (HAIR^R2'^', wherein n' is 1 or 2, and R1and R2are independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2"Bu, and CMe2CH2'Bu. In an embodiment, precursor-B is selected from HB(OCR1R2CR3R4O), HB(OCR1'R2'CR3'R4'CR5'R6'O), HBcat, (9-BBN), or (HBR7'2)„', wherein n' is 1 or 2, the substituents R1, R2, R3, R4, R5and R6are independently selected from H, Me, Et, "Pr and 'Pr, and R7is independently selected from Me, Et, "Pr, 'Pr, "Bu, 'Bu, "Bu, 'Bu, "Pent, CHMe"Pr, CHMe'Pr, CHEt2, CH2'Bu, CH2"Bu, CH2'Bu, CH2SiMe3, and cyclopentyl, CHMe"Pr, CHMe'Pr, CHEt2, CMe2Et, CMe2"Pr, CMe2'Pr, CMe2"Bu, CMe2'Bu, CMe2"Bu, and CMe2CH2 / Bu. In an embodiment, the deposition cycle further comprises use of a purge gas to remove at least a portion of excess vapour phase precursor- A, and reaction byproducts if any, from the reaction space after contacting the substrate with vapour phase precursor-A and before contacting the surface with vapour phase precursor-B, and the use of a purge gas to remove at least a portion of excess precursor-B, and reaction byproducts if any, from the reaction space after contacting the substrate with precursor-B and before contacting the surface with vapour phase precursor-A. In an embodiment, the process is an atomic layer deposition (ALD) process. In some embodiments, the deposition process is carried out witha continuous flow of hydrogen gas (H2), or a mixture of hydrogen gas (H2) and an inert gas. In some embodiments, the process is carried out with a periodic flow of hydrogen gas (H2), or a mixture of hydrogen gas (H2) and an inert gas. In some embodiments, hydrogen gas (H2), or a mixture of hydrogen gas (H2) and an inert gas is introduced during a pulse of precursor B and / or between a pulse of precursor-B and a pulse of precursor-A. In some embodiments, the deposited film is subsequently heated under a flow hydrogen gas (H2), or a mixture of hydrogen gas (H2) and an inert gas. The skilled person would appreciate in such embodiments that neither precursor on its own reacts appreciably with H2 under the conditions of the deposition experiment. In an embodiment, the deposited fdm has a germanium content of greater than or equal to 80 at% within the bulk portion of the fdm. In an embodiment, precursor-A is Ge(OCH2CH2NMe2)2 and precursor-B is pinacolborane (HBpin). In an embodiment, the substrate is heated to a temperature of about 20 °C to about 400 °C. In an embodiment, the fdm growth rate is greater than 0. 1 A / cycle. In an embodiment, the fdm growth rate is greater than 0.2 A / cycle. In an embodiment, selective deposition is achieved, with a deposition rate on a target surface material that is more than 5 times higher than that on a non-target surface material. In an embodiment, the fdm growth rate is more than 10 times greater on H-terminated silicon than on an oxide material such as silicon oxide, germanium oxide, aluminum oxide, a rare earth metal oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, or indium tin oxide. In an embodiment, the process is interspersed with one or more other fdm deposition process for the purpose of fabricating a binary, ternary or quaternary material, a doped material, or a nanolaminate. In an embodiment, the process is used for electronic device fabrication. In an embodiment, the process is used for memory or logic device fabrication. In an embodiment, the process is used for photonic device fabrication. In an embodiment, the process is used for quantum device fabrication.

[0112] The following non-limiting examples are illustrative of the present application:EXAMPLESGeneral Materials & Methods

[0113] All deposition experiments were conducted in a home-built ALD reactor. The reactor was made up of a reaction chamber (a 6” ConFlat™ cube) housed within an oven. The reaction chamber contained a flange-mounted 2-inch heated substrate stage (HeatWave labs) which can be heated independently to a temperature equal to or above the temperature of the surrounding oven. The reaction chamber was connected to an Ebara EV-A10-2S-Pdry semiconductor vacuum pump via a foreline that included a Mass-Vac 10” body diameter multi-trap with stainless steel gauze and activated charcoal filter elements, and several manual bellows valves. The foreline also connected to a convection-enhanced Pirani vacuum gauge that was not connected during deposition. Eight separate precursor lines were attached to the top of the reaction chamber. Two lines could be used for room temperature precursor delivery, using precursor delivery vessels of a non-flow-through design. Three lines could be used for gaseous precursor delivery. Three lines attached to heated bubblers of a flow-through design; the heated bubbler used in this work was housed in an oven connected back-to-back to the oven that contains the reaction chamber.

[0114] The reactor was operated under a constant stream of argon (99.998%) which was purified by passage through an Entegris™ purifier cartridge designed to achieve O2 and H2O concentrations below 0. 1 ppb. Argon was supplied to each of the eight precursor lines via a mass flow controller and pneumatically actuated diaphragm valve, and for all deposition experiments, argon flows of 20 seem were used on each line, resulting in a reactor pressure of approximately 0.3 Torr during deposition.

[0115] The germanium (e.g., Ge(OCH2CH2NMe2)2) precursor delivery vessel (flow through design) was heated to 105 °C, and the HBpin precursor delivery vessel (non-flow through design) was cooled to 6-8 °C using a thermoelectric cooling plate. For all depositions, unless otherwise stated, the purge time following each precursor pulse was 45 s. The ALD reactor used in this work requires longer pulses than most commercial ALD reactors due to the significantly larger reaction chamber volume and the skilled person could readily adjust times accordingly.

[0116] Deposition experiments used double side polished Si(100) wafers with a layer (100 nm) of oxide, or freshly prepared hydrogen-terminated Si(100) substrates. Si(100) substrates with a layer of thermal oxide (SiC>2 / Si) were plasma cleaned (air plasma) for 10 minutes immediately prior to being loaded into the ALD reactor and placed under vacuum. Hydrogen- terminated Si(100) (H-Si) substrates were prepared using the following procedure based on previously reported literature procedures [(a) Buriak, J. M. Chem. Rev. 2002, 102, 1271-1308, (b) Jayachandran, S.; Delabie, A.; Billen, A.; Dekkers, H.; Douhard, B.; Conard, T.; Meersschaut, J.; Caymax, M.; Vandervorst, W.; Heyns, M. Appl. Surf. Sci. 2015, 324, 251-257, and (c) Sun, Q. Y.; de Smet, L.; van Lagen, B.; Wright, A.; Zuilhof, H.; Sudholter, E. J. R. Angew. Chem. Int. Ed 2004, 43, 1352-1355]: 1 cm x 1 cm sections of a Si(100) wafer with a <5 nm layer of native oxide were placed in beaker containing 1:3 H2O2 / H2SO4 mixture at 85 °C for10 minutes, followed by a quick rinse under a stream of ultra-pure water. The wafer was then placed in a PTFE beaker containing 2% HF(aq) for 1-2 minutes, rinsed in a stream of ultra-pure water, and dried under a rapid flow of nitrogen or argon. The wafer was then quickly (within 2 or 3 minutes) loaded into the ALD reactor and placed under vacuum.

[0117] Thin fdm X-ray diffraction (XRD) was carried out using a Bruker™ D8 Discover diffractometer equipped with a Vantec 500 area detector and a focused Cu source with Ka radiation (X = 1.5418 A) operated at 40 kV and 40 mA. All films obtained in these examples were amorphous by XRD.

[0118] Average film thickness values were obtained by variable angle spectroscopic ellipsometry (V ASE) using a J. A. Woolam M 2000 spectroscopic ellipsometer. Measurements were taken from 55° to 75° at 5° increments with an acquisition time of 10 seconds. Experimental data were modeled using the CompleteEase software provided with the spectrometer. For films deposited on SiO Si, the model used to fit the experimental data was made up of a Si substrate with a S1O2 layer of fixed thickness (thickness determined by VASE analysis of the bare substrates) followed by a B-Spline model. Films deposited on H-Si were treated analogously, but without the SiCE layer in the model. Models utilized data obtained in the angle and wavelength ranges 65-70° and 300-900 nm. In all cases, VASE measurements were carried out at 3 points on the wafer, and quoted thickness values are an average of all three measurements. For these thin amorphous films, the VASE data is difficult to model, and thickness values from VASE should be considered to be relative values, rather than absolute values.

[0119] Selected films were analyzed by top-down and / or cross-sectional scanning electron microscopy (SEM) using an FEI Magellan 400, with analysis using ImageJ. Cross-sectional SEM was used to confirm self-limiting growth on H-Si at 225 and 250 °C.

[0120] Film composition was analyzed by X-ray photoelectron spectroscopy (XPS) using a Thermo Fisher Scientific™ Escalab 250Xi (monochromatic Al-Ka source) with a nominal spot size of 400 pm. Electron micrographs were obtained using a FEI Magellan 400 and analyzed using ImageJ. All deposited thin films were exposed to air for minutes, hours or several days prior to analysis.Example 1.

[0121] Deposition of elemental germanium was carried out using the precursor molecule Ge(OCH2CH2NMe2)2 and the co-reactant HBpin (pin = OCMe2CMe2O). Each deposition cycleinvolved a 0.2 s pulse of Ge(OCH2CH2NMe2)2, followed by a 45 s inert gas purge, followed by a 0.05 s pulse of HBpin, followed by a 45 s inert gas purge. The substrate temperature was 225 °C, deposition was carried out on both H-terminated silicon and SiC Si substrates using 1000 deposition cycles. The films were shown to be amorphous by thin film X-ray diffraction, and the film was analyzed by FESEM (FIG. 1). Film thickness values were obtained by VASE. On H- Si, self-limiting growth was confirmed by cross-sectional SEM.Example 2.

[0122] The method of Example 1 was repeated using 4000 deposition cycles and an IT- terminated silicon substrate. This experiment afforded a film which was used to assess film morphology by FESEM (FIG. 2) and film composition by XPS (FIG. 3 and FIG. 4). XPS depth analysis revealed that after sputtering through the passivated surface, the deposited film comprises elemental germanium, with boron content below levels detectable by XPS, and less than 10 at% carbon and oxygen impurities within the bulk portion of the film.Example 3.

[0123] Multiple depositions were carried out using modified versions of the method in Example 1. These experiments investigated different precursor pulse and purge durations in order to test self-limiting growth, and were carried out at multiple temperatures to probe the extent to which the film growth rate varies with temperature. Selected data from these experiments is summarized in FIGs. 5-7; where each data point for a particular substrate material represents a different deposition experiment. Additional selected data from experiments is summarized in FIGs. 8-10; where each data point for a particular substrate material represents a different deposition experiment. Findings from these experiments include: (a) film deposition was achieved at various temperatures between 200 and 300 °C; (b) self-limiting film growth, which is a requirement for an ALD process, was demonstrated at 225 °C and 250 °C on a hydrogen-terminated silicon substrate; (c) the deposition rate at 225 and 250 °C remained approximately the same after doubling the inert gas purge durations; and (d) at some temperatures (e.g. 300 °C), the growth rate on H-terminated silicon far exceeds that on SiCE, indicating the possibility for area-selective germanium deposition.Example 4.

[0124] Deposition of elemental germanium was carried out using the precursor molecule Ge(OCMe2CH2NMe2)2 and the co-reactant HBpin (pin = OCMe2CMe2O). Each deposition cycleinvolved a 0.2 s pulse of Ge(OCMe2CH2NMe2)2, followed by a 45 s inert gas purge, followed by a 0.05 s pulse of HBpin, followed by a 45 s inert gas purge. The substrate temperature was 225 °C, and deposition was carried out on an H-terminated silicon substrate using 1000 deposition cycles. In a subsequent experiment, deposition was carried out in an identical manner to that described above, but with a 0.4 s pulse of Ge(OCMe2CH2NMe2)2 and a 0.1 s pulse of HBpin. VASE measurements afforded nearly identical film thickness values (20 and 21 nm), indicative of sei f-1 imiting growth. The films were shown to be amorphous by thin film X-ray diffraction.Comparative Example.

[0125] ALD reactor experiments were carried out to test whether H2 would result in film deposition when combined with Ge(OCH2CH2NMe2)2 in an ALD-type experiment. Each deposition cycle involved a 0. 1 s pulse of Ge(OCH2CH2NMe2)2, followed by a 45s purge, then 10s of a 50 seem flow of H2, then a 45s purge, using a substrate temperature of 150 or 300 °C, with both H-terminated silicon and SiCE / Si substrates, and 1000 deposition cycles were carried out. VASE indicated the absence of any deposited film on the SiCL / Si substrates. For the H-terminated substrates, VASE indicated a film thickness value of 3-4 nm, while not wishing to be limited by theory, consistent with either (a) a native oxide layer formed as a result of exposure of an uncoated H-terminated Si wafer to air for several hours after removal from the ALD reactor and prior to VASE measurement, or (b) deposition of a germanium- containing film with a thickness that corresponds to a very low growth rate. The absence of film growth using H2 in combination with Ge(OCH2CH2NMe2)2 and a S i O2 / S i substrate, and the absence or very low rate of film growth using H2 in combination with Ge(OCH2CH2NMe2)2 indicated that H2 was not suitable as a co-reactant for germanium deposition in combination with Ge(OCH2CH2NMe2)2.

[0126] While the present application has been described with reference to examples, it is to be understood that the scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0127] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present application is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for the term.

Claims

CLAIMSWhat is claimed is:

1. A process for depositing a material comprising elemental germanium, the process comprising a deposition cycle comprising: exposing a heated substrate to a vapor comprising a germanium-containing precursor compound; and exposing the heated substrate to a vapor comprising a co-reactant selected from a base-free hydroborane, a hydrosilane, a hydrostannane and a hydroalane.

2. The process of claim 1, wherein the co-reactant comprises a base-free hydroborane.

3. The process of claim 1, wherein the co-reactant comprises a hydrosilane.

4. The process of claim 2, wherein the base-free hydroborane is selected from:(i) HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, RlcandRldare each independently selected from H and Ci-4alkyl;(ii) HB(OCR2aR2bCR2oR2dCR2eR2fO), wherein R2a, R2b, R2°, R2d, R2eand R2fare each independently selected from H and Ci-4alkyl;(iii) HBcat;(iv) (9-BBN)n, wherein n is 1 or 2;(v) (HBR32)m, wherein m is 1 or 2, each R3is independently selected from Ci-salkyl and Cs-scycloalkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom; and(Vl) B2H6.

5. The process of claim 4, wherein the base-free hydroborane is HB(OCRlaRlbCRlcRldO), wherein Rla, Rlb, Rlcand Rldare each independently selected from H and Ci-4alkyl.

6. The process of claim 5, wherein the base-free hydroborane is pinacolborane (HBpin).

7. The process of any one of claims 1 to 6, wherein the germanium- containing precursor compound is selected from:(i) Ge(OR4)4, wherein each R4is independently selected from Cj-salkyl and C3- 7cycloalkyl and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom;(ii) Ge(NR5R6)4, wherein each R5and R6are independently selected from Ci- salkyl and C3-7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom;(iii) Ge(OR7)2, wherein each R7is independently selected from Ci-salk l. CTrcycloalkyl. CR7aR7aCH2NR7bR7b, CR7aR7aCH2CH2NR7bR7b, CH2CR7aR7aCH2NR7bR7b, CR7aR7aCH2OR7b, CR7aR7aCH2CH2OR7band CH2CR7aR7aCH2OR7b, wherein each R7ais independently selected from H and Ci-3alkyl, each R711is independently selected from Ci-3alkyl, and one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom;(iii) Ge(NR8R9)2, wherein each R8is independently selected from Cj -5 alky I and C3- 7cycloalkyl, wherein one or more available carbon atoms in the Ci-salkyl is / are optionally replaced by a silicon atom; and each R9is independently selected from Ci-salkyl, C3-7Cycloalkyl, CR9aR9aCH2NR9bR9b, CR9aR9aCH2CH2NR9bR9b, CH2CR9aR9aCH2NR9bR9b, CR9aR9aCH2OR9b, CR9aR9aCH2CH2OR9b, and CH2CR9aR9aCH2OR9b, wherein each R9ais independently selected from H and Ci-3alkyl, each R9bis independently selected from Ci-3alkyl, and one or more available carbon atoms in the Ci- salkyl is / are optionally replaced by a silicon atom; and(iv) Ge{N(SiR10R11R12)2}2, wherein each R10, R11and R12is independently selected from Ci-3alkyl.

8. The process of claim 7, wherein the germanium-containing precursor compound is Ge(NR8R9)2or Ge{N(SiR10R11R12)2}2.

9. The process of claim 7, wherein the germanium-containing precursor compound is Ge(OR7)2.

10. The process of claim 9, wherein each R7is independently CR7aR7aCH2NR7bR7b, wherein each R7ais independently selected from H and Ci-3alkyl and each R7bis independently selected from Ci-3alkyl.

11. The process of claim 9, wherein the germanium-containing precursor compound is Ge(OCH2CH2NMe2)2.

12. The process of claim 9, wherein the germanium-containing precursor compound is Ge(OCMe2CH2NMe2)2.

13. The process of any one of claims 1 to 12, wherein the material is in the form of a film.

14. The process of claim 13, wherein the process further comprises repeating the deposition cycle until a film of a desired thickness is deposited.

15. The process of any one of claims 1 to 14, wherein subsequent to exposing to the vapor comprising the germanium-containing compound, the process further comprises: purging with a purge gas to remove at least a portion of excess germanium- containing precursor compound and / or byproducts.

16. The process of any one of claims 1 to 15, wherein subsequent to exposing to the vapor comprising the co-reactant, the process further comprises: purging with a purge gas to remove at least a portion of excess co-reactant and / or byproducts.

17. The process of any one of claims 1 to 16, wherein the process comprises an atomic layer deposition (ALD) process.

18. The process of claim 17, wherein the process comprises a thermal ALD process.

19. The process of any one of claims 1 to 18, wherein the heated substrate comprises IT- terminated silicon.

20. The process of any one of claims 1 to 19, wherein the film growth rate is greater than 0.1 A / deposition cycle.

21. The process of any one of claims 1 to 20, wherein the heated substrate comprises a target surface material and a non-target surface material, and wherein the film comprising elemental germanium is deposited on the target surface material at a higher film growth rate than the non-target surface material.

22. The process of claim 21, wherein the target surface material comprises H-terminated silicon and the non-target surface material comprises silicon oxide, germanium oxide, aluminum oxide, a rare earth metal oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, indium tin oxide or combinations thereof.

23. The process of claim 20, wherein the non-target surface material comprises silicon oxide.

24. A process for preparing a binary, ternary or quaternary material, a doped material, or a nanolaminate, the process comprising: depositing a film comprising elemental germanium by a process as defined in any one of claims 1 to 23; and one or more additional film deposition processes.

25. Use of a process as defined in any one of claims 1 to 24 in the fabrication of an electronic device, memory or logic device, photonic device or quantum device.

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