Silicon Compound Film by Selective Deposition

Abstract

Methods for forming silicide films are disclosed. Methods for selectively depositing metal-containing films on silicon surfaces and further processing them to form silicide films are disclosed. Certain embodiments of the present disclosure relate to forming silicide films on FinFET structures without forming a metal layer on the dielectric. [Selected Figure] Figure 1

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a method for forming a silicon compound film. More specifically, embodiments of the present disclosure are directed to a method of selectively depositing a film on a silicon surface and further processing to form a silicon compound film.

Background Art

[0002] A fin field effect transistor, also known as a FinFET, is a type of non-planar or three-dimensional transistor used in the design of state-of-the-art processors. Similar to previous planar designs, it is typically built on a SOI (silicon-on-insulator) substrate. However, in the FinFET design, a conductive channel above the level of the insulator is also used to create a thin silicon-based structure in the shape of a fin called a gate electrode. This fin-type electrode allows multiple gates to operate on a single transistor. FinFET devices also have switching times and current densities that are significantly faster than mainstream CMOS technology.

[0003] There is a continuing need for new FinFET designs. Specifically, new materials and surface compositions are needed that allow for an extended set of design options. Selective deposition has shown promise because it allows for the deposition of a film on a selected surface and has the potential to simplify the integration scheme.

[0004] Selective deposition of materials can be performed in a variety of ways. For example, in some processes, based on surface chemistry, selectivity can be inherent to the surface. These processes are rather rare and typically require surfaces with significantly different surface energies, such as metals and dielectrics. In FinFETs and other cases where the surfaces are similar (e.g., SiO2 and SiN), one surface selectively reacts while the other does not, and surface treatment is employed to effectively block surface reactions during subsequent deposition processes to selectively block the surface. Additionally, some deposition precursors are not effectively blocked with current technology.

[0005] Accordingly, there is a continuing need in the art for methods and materials that selectively suppress deposition on certain surfaces while selectively depositing a film on other surfaces. SUMMARY OF THE INVENTION

[0006] One or more embodiments of the present disclosure are directed to a method of processing a substrate that includes providing a substrate having a first semiconductor surface and a second dielectric surface. The substrate is exposed to a blocking compound to selectively form a blocking layer on the second surface relative to the first surface. The substrate is exposed to a titanium precursor to selectively deposit a Ti-containing layer on the first surface relative to the second surface. The substrate is heated to form a modified first surface that includes titanium and silicon. (Modified)

[0007] Additional embodiments of the present disclosure are directed to a method of processing a substrate that includes providing a substrate having a first semiconductor surface and a second dielectric surface. The substrate is exposed to a blocking compound to selectively form a blocking layer on the second surface. The substrate is exposed to a titanium precursor to selectively deposit a Ti-containing layer on the first surface relative to the second surface. The substrate is exposed to a germanium precursor to selectively deposit a Ge-containing layer on the first surface relative to the second surface. The substrate is heated to form a modified first surface that includes titanium, germanium, and silicon.

[0008] Further embodiments of the present disclosure are directed to a method of processing a substrate that includes providing a substrate having a first silicon surface and a second silicon oxide surface. The substrate is exposed to a blocking compound to selectively form a blocking layer on the second surface. The substrate is exposed to a titanium precursor to selectively deposit a Ti-containing layer on the first surface relative to the second surface. The substrate is exposed to a silicon precursor to selectively deposit a Si-containing layer on the first surface relative to the second surface. The substrate is heated to form a modified first surface consisting essentially of TiSi2.

[0009] To better understand the above features of the present disclosure, a more detailed description of the present disclosure, briefly summarized above, can be obtained by reference to the embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and should not be considered as limiting the scope of the present disclosure, which may admit of other equally effective embodiments.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

[0011] In the accompanying drawings, similar components and / or features may have the same reference numerals. Further, various components of the same type may be distinguished by following the reference numerals with a dash and a second numeral that differentiates similar components from each other. Where only a first reference numeral is used herein, the description applies to any one of the similar components having the same first reference numeral, regardless of the second reference numeral.

Modes for Carrying Out the Invention

[0012] Before describing some exemplary embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of the configurations or process steps described in the following description. The present disclosure is capable of other embodiments and can be implemented or executed in various ways.

[0013] Embodiments of the present disclosure provide a method of processing a substrate that forms a TiSi film on a semiconductor surface but not on a dielectric surface. The processes of various embodiments use selective deposition to form a film on a portion of the substrate and further process it.

[0014] As used herein, "substrate surface" refers to any portion of the substrate or a portion of the surface of a material formed on the substrate on which film processing is performed. For example, the substrate surface on which processing can be performed may include, depending on the application, silicon, silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other material such as metals, metal nitrides, metal alloys, and other conductive materials. The substrate includes, but is not limited to, semiconductor wafers. The substrate may be exposed to a pretreatment process for polishing, etching, reducing, oxidizing, hydroxylation, annealing, UV curing, electron beam curing, and / or baking the substrate surface. In addition to direct film processing on the surface of the substrate itself, in the present invention, any of the disclosed film processing steps can also be performed on an underlying layer formed on the substrate as disclosed in more detail below, and the term "substrate surface" is intended to include such an underlying layer as the context indicates. Thus, for example, when a film / layer or a partial film / layer is deposited on the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface. The substrate can have various dimensions, such as wafers with a diameter of 200 mm or 300 mm, and rectangular or square panels. In some embodiments, the substrate includes a rigid discrete material.

[0015] As used herein, "atomic layer deposition" refers to the sequential exposure of a substrate to two or more deposition gases for depositing a layer of material on the surface of the substrate. As used in this specification and the appended claims, terms such as "reactive compound", "reactive gas", "reactive species", "precursor", "process gas", "deposition gas", etc. are used interchangeably to mean a substance having species capable of reacting with the surface of the substrate or a material on the surface of the substrate in a chemical reaction (e.g., substitution, elimination, addition, oxidation, reduction). The substrate or a portion of the substrate is sequentially exposed to two or more reactive compounds introduced into the reaction zone of the processing chamber. In a time-domain process, the exposure to each reactive compound is separated by a time delay, allowing each compound to react with the surface of the substrate and then be purged from the processing chamber. In a spatial process, different portions of the substrate surface or materials on the substrate surface are exposed to two or more reactive compounds simultaneously such that any given point on the substrate is not substantially simultaneously exposed to more than one reactive compound. As used in this specification and the appended claims, the term "substantially" as used in this context means that, as would be understood by one of ordinary skill in the art, a small portion of the substrate may be exposed to multiple reactive gases simultaneously by diffusion, but simultaneous exposure is not intended.

[0016] In one aspect of the time domain process, a first reactive gas (i.e., a first precursor or Compound A) is pulsed into the reaction zone, followed by a first time delay. Next, a second precursor or Compound B is pulsed into the reaction zone, followed by a second delay. During each time delay, a purge gas such as argon is introduced into the processing chamber to purge the reaction zone or otherwise remove any residual reactive compounds or reaction by-products from the reaction zone. Alternatively, the purge gas can be flowed continuously throughout the deposition process such that only the purge gas flows during the time delay between pulses of the reactive compound. Alternatively, the reactive compounds are pulsed until the desired molecular layer or layer thickness is formed on the substrate surface. In any scenario, the process of pulsing Compound A, the purge gas, Compound B, and the purge gas is one cycle. The cycle can start with either Compound A or Compound B and can continue in each order of the cycle until a film of a predetermined thickness is achieved.

[0017] In an embodiment of the spatial process, a first reactive gas and a second reactive gas are fed into the reaction zone simultaneously but separated by an inert gas curtain and / or a vacuum curtain. The substrate is moved relative to the gas delivery device such that any given point on the substrate is exposed to the first reactive gas and the second reactive gas, but not simultaneously.

[0018] One or more embodiments of the present disclosure advantageously provide a method of processing a substrate that includes selectively depositing a film on a semiconductor surface (e.g., silicon) without substantially depositing on a dielectric surface (e.g., silicon oxide). In some embodiments, the selective deposition is advantageously achieved by combining a selective surface blocking step that utilizes a blocking compound that selectively reacts with the dielectric surface to form a blocked surface. The deposition proceeds on other substrate surfaces that remain unblocked.

[0019] The general surface mechanism of one or more embodiments of the present disclosure can be performed to block a dielectric surface and then deposit these films on a semiconductor surface while stopping or minimizing the deposition of the films on the dielectric surface. Without being bound by a particular theory of operation, when used with the precursors described herein, the blocking compounds described herein are thought to prevent the reaction of the precursors with the dielectric surface.

[0020] In some embodiments, the dielectric surface groups can react with a blocking molecule that has reactivity with -OH termini rather than -H termini. These molecules can be introduced onto the substrate via gas-phase delivery, either in solution form or as is. After selective surface blocking, a film can be selectively grown on the semiconductor surface using an ALD or CVD process.

[0021] Referring to FIGS. 1 and 2, one or more embodiments of the present disclosure are directed to a method 200 of processing a substrate. The method includes providing a substrate that includes a first material 20 and a second material 30. When used in this context, the term "providing a substrate" means that the substrate is placed in a position for processing (e.g., within a processing chamber). In some embodiments, the first material 20 includes a semiconductor, and the first material 20 has a semiconductor surface 25. In some embodiments, the second material 30 includes a dielectric, and the second material 30 has a dielectric surface 35. In this regard, the semiconductor surface 25 may sometimes be referred to as a first semiconductor surface. Similarly, the dielectric surface 35 may sometimes be referred to as a second dielectric surface. It should be understood that the present disclosure does not require multiple dielectric surfaces.

[0022] The first material 20 can be any suitable semiconductor material. In some embodiments, the first material 20 consists essentially of silicon. As used herein and in the appended claims, a material that "consists essentially of" the recited composition means that about 95% or more, 98% or more, or 99% or more of the material is the recited composition.

[0023] The second material 30 can be any suitable dielectric material. In some embodiments, the second material 30 includes silicon oxide. In some embodiments, the second material 30 consists essentially of SiO2. When used in this context, silicon oxide is any suitable material that includes silicon and oxygen. In some embodiments, the second surface 35 consists essentially of silicon and oxygen. In some embodiments, the material of the second surface 35 is stoichiometric silicon oxide. In some embodiments, the ratio of silicon to oxygen at the second surface 35 is about 1:2. In some embodiments, the ratio of silicon to oxygen atoms is a non-stoichiometric ratio. In some embodiments, the ratio of silicon to oxygen at the second surface 35 is less than 1:2. In some embodiments, the ratio of silicon to oxygen at the second surface 35 is greater than 1:2.

[0024] FIG. 1 shows a schematic cross-sectional view of a substrate 10 having a three-dimensional (3D) structure formed on a substrate, according to one or more embodiments described herein. In some embodiments, the substrate 10 includes a 3D structure extending from a base layer. In some embodiments, the base layer can be a dielectric material such as an oxide, a nitride, etc. For example, the substrate 10 can be a silicon-on-insulator substrate. The embodiments described herein are generally performed with reference to a 300 mm circular substrate, however, it is contemplated that various other substrate dimensions can benefit from the embodiments described herein.

[0025] The 3D structure of the substrate can be formed on the substrate layer by various patterning and etching processes. In some embodiments, the 3D structure can be formed in dimensions suitable for implementation as fin-type field-effect transistors (FinFETs) of complementary metal-oxide-semiconductor (CMOS) transistors. However, other transistor types, substrate features, and featureless substrate surfaces may also benefit from the embodiments described herein. In some embodiments, the 3D structure may be suitable for use at current technology nodes and advanced technology nodes, such as nodes less than 10 nm, and may have corresponding dimensions.

[0026] The 3D structure may be the same material as the substrate layer or a different material from the substrate layer (see FIG. 1). In some embodiments, the 3D structure can be formed from silicon. In some embodiments, the 3D structure extends from the substrate layer and is separated by trenches.

[0027] At 202, a substrate 10 having a first surface 25 and a second surface 35 is exposed to a blocking compound. The blocking compound can be any suitable compound that can react with the second surface 35 but cannot react with the first surface 25. The blocking compound reacts with the second surface 35 to form a blocking layer 40 on the second surface 35.

[0028] In some embodiments, the blocking compound includes a compound of the general formula R3Si-X, where each R is independently a C1-C4 alkyl and X is a leaving group. As used in this context, C1-C4 alkyl means a saturated carbon chain having 1 to 4 carbon atoms. In some embodiments, these carbon chains are straight. In some embodiments, these carbon chains are branched. In some embodiments, each R is methyl. In some embodiments, X is selected from a halide, azide, amino, hydrazide, cyanide, or isocyanate group.

[0029] In some embodiments, X comprises a primary, secondary, or tertiary amine having a linear C1-6 alkyl or branched C1-4 alkyl group. In some embodiments, X is a cyclic amine up to a 6-membered ring. In some embodiments, X comprises a cyclic pyrrolyl group (-N(CH2)4). In some embodiments, X comprises a cyclic pyrrolidine group (-N(CH)4). In some embodiments, the blocking compound comprises trimethylsilylpyrrolidine (CH3)3SiN(CH2)4. In some embodiments, the blocking compound consists essentially of trimethylsilylpyrrolidine. Trimethylsilylpyrrolidine is a compound of formula I below: TIFF0007698951000001.tif20170

[0030] When used in this context, the term "consisting essentially of" means that the reaction components of the blocking compound (excluding inert, diluent, or carrier species) are, on a molar basis, at least about 95%, at least about 98%, or at least about 99% of the species described above.

[0031] The blocking layer can be formed at any suitable temperature. In some embodiments, the substrate is maintained at a temperature in the range of about 200°C to about 500°C, in the range of about 250°C to about 450°C, in the range of about 250°C to about 400°C, or in the range of about 300°C to about 450°C. In some embodiments, the substrate is maintained at a temperature of about 450°C or less, about 400°C or less, about 375°C or less, about 350°C or less, about 300°C or less, or about 250°C or less. In some embodiments, the substrate is maintained at a temperature of about 200°C or more, about 225°C or more, about 250°C or more, about 300°C or more, or about 350°C or more.

[0032] In 204, after the formation of the blocking layer 40, selective deposition of the metal layer 50 on the first surface 25 can be performed. The metal layer 50 can be deposited by any suitable deposition technique known to those skilled in the art. Suitable techniques include, but are not limited to, chemical vapor deposition, atomic layer deposition, or physical vapor deposition. In some embodiments, the metal layer 50 contains titanium, and the metal layer 50 is deposited by atomic layer deposition.

[0033] The following description discloses a general process for depositing a metal layer on the substrate 10. In some embodiments, the metal is titanium and the metal layer is the titanium-containing layer 50. In some embodiments, the metal layer further includes an additional metal alloyed with titanium.

[0034] In some embodiments, germanium is alloyed with titanium. In some embodiments, germanium is deposited separately from titanium to form a bilayer film.

[0035] The substrate 10 having the first surface 25 and the blocking layer 40 is exposed to a metal precursor. In some embodiments, the metal precursor chemisorbs onto the first surface 25 to deposit a layer of metal species on the first surface 25. In these embodiments, the layer of metal species on the first surface 25 reacts with a reagent to form a metal film. In some embodiments, the metal precursor and the reagent are simultaneously exposed to the substrate 10 and react to form a metal film on the first surface 25. In some embodiments, the metal precursor and the reagent are each separately exposed to the substrate 10. In some embodiments, the metal precursor and the reagent are simultaneously exposed to the substrate 10. Some embodiments deposit the metal film 50 via a time-domain ALD process. Some embodiments deposit the metal film 50 via a spatial ALD process.

[0036] A metal film is a common term used to describe a metal-containing material. In some embodiments, the metal film is a pure metal film. As used in this context, a "pure metal film" means that the metal atoms are, on an atom basis excluding hydrogen, at least about 98%, 99%, or 99.5% of the metal film. In some embodiments, the metal film contains other atoms. In some embodiments, the metal film contains one or more of oxygen, nitrogen, carbon, silicon, boron, or germanium.

[0037] A metal precursor can be any suitable compound that can react with a reagent to form the metal film 50. In some embodiments, the metal precursor contains at least one amine ligand. In some embodiments, the metal precursor has the formula M(NR’2) a and includes a compound of the formula, where each R’ is independently H, C1-C4 alkyl, or trimethylsilyl, and a is 1 or greater. As used in this context, C1-C4 alkyl means a saturated carbon chain having 1 to 4 carbon atoms. In some embodiments, these carbon chains are straight. In some embodiments, these carbon chains are branched.

[0038] In some embodiments, R’ consists essentially of ethyl groups. In some embodiments, R’ consists essentially of methyl groups. In some embodiments, the R’ groups within a single ligand are the same (e.g., N(CH3)2). In some embodiments, the R’ groups within a single ligand are different (e.g., N(CH3)(C2H5)). In some embodiments, the metal precursor consists essentially of tetrakis(ethylmethylamide)titanium. As used in this context, the term "consists essentially of" means that the reaction components of the metal precursor (excluding inert, diluent, or carrier species) are, on a molar basis, at least about 95%, 98%, or 99% of the above species.

[0039] In some embodiments, the metal precursor contains at least one halogen CompoundIt contains a ligand. In some embodiments, the metal precursor does not contain a metal halide. In some embodiments, the film contains titanium and the metal precursor does not contain TiCl4.

[0040] In some embodiments, the metal precursor contains at least one oxo ligand. In some embodiments, the oxo ligand has the general formula -OR * wherein R * is a C1-C8 alkyl group. In some embodiments, the at least one oxo ligand is selected from the group consisting of methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, and ethylhexyloxy.

[0041] The metal of the metal precursor can be any suitable metal. In some embodiments, the metal of the metal precursor is selected from Ti, Zr, Hf, or Ta. In some embodiments, the metal precursor consists essentially of a Ti-containing compound. In this regard, the metal precursor may be referred to as a titanium precursor. In some embodiments, the metal precursor consists essentially of a Zr-containing compound. In some embodiments, the metal precursor consists essentially of an Hf-containing compound. In some embodiments, the metal precursor consists essentially of a Ta-containing compound.

[0042] The reagent can be any suitable compound capable of reacting with the metal precursor to form the metal film 50. In some embodiments, the reagent is exposed to a substrate separate from the metal precursor. Suitable reagents include, but are not limited to, hydrogen, ammonia, hydrazine, hydrazine derivatives, silane, halosilane, polysilane, borane, haloborane, and other co-reagents for making metal, metal nitride, metal silicon compound, and / or metal boride films. Suitable reagents can also include, but are not limited to, oxygen, ozone, water, and other oxygen-based reagents for making metal or metal oxide films. In some embodiments, a plasma of the reagent is used to form the metal film 50. In some embodiments, the plasma of the reagent is generated remotely. In some embodiments, the reagent includes one or more of hydrogen, ammonia, or water.

[0043] In some embodiments, the reagent consists essentially of hydrogen and the metal film is a pure metal film. In some embodiments, the reagent consists essentially of ammonia and the metal film is a metal nitride film. In some embodiments, the reagent consists essentially of water and the metal film is a metal oxide film. When used in this context, the term "consists essentially of" means that the reagent (excluding inert, diluent, or carrier species) is, on a molar basis, about 95% or more, 98% or more, or 99% or more of the above components. When used in this context, a pure metal film is any film consisting essentially of metal atoms. When used in this context, a metal nitride film is any film containing metal atoms and nitrogen atoms. When used in this context, a metal oxide film is any film containing metal atoms and oxygen atoms. A film containing atoms other than metal (e.g., metal nitride or metal oxide) may or may not be composed of stoichiometric ratio of atoms.

[0044] At 206, a germanium-containing layer is deposited on the first surface. The deposition of the germanium-containing layer is an optional process. In some embodiments, a titanium-containing layer is deposited on the first surface, and the germanium-containing layer is also deposited on the first surface. In some embodiments, the titanium-containing layer is deposited first. In some embodiments, the germanium-containing layer is deposited first.

[0045] The germanium-containing layer can be deposited by any suitable process. In some embodiments, the germanium-containing layer is deposited by a process similar to the process described above for a metal layer where germanium is the metal.

[0046] At 208, a silicon-containing layer is deposited on the first surface. The deposition of the silicon-containing layer is an optional process. In some embodiments, a titanium-containing layer is deposited on the first surface, and the silicon-containing layer is also deposited on the first surface. In some embodiments, the titanium-containing layer is deposited first. In some embodiments, the silicon-containing layer is deposited first.

[0047] The silicon-containing layer can be deposited by any suitable process. In some embodiments, the silicon-containing layer is deposited by a process similar to the process described above for a metal layer where silicon is the metal. In some embodiments, the silicon-containing layer is deposited by exposing the substrate to a silicon precursor. In some embodiments, the substrate is also exposed to a reactant. In some embodiments, the silicon-containing layer is deposited on both the first surface and the blocking layer. In some embodiments, the silicon-containing layer can be deposited by PVD and / or CVD. In some embodiments, the silicon-containing layer is amorphous. In some embodiments, the silicon-containing layer is polycrystalline. In some embodiments, the silicon-containing layer is deposited epitaxially.

[0048] In 210, after the formation of the metal film 50, the substrate is heated to form a modified first surface 60. Without being bound by theory, it is believed that by heating the substrate, the metal layer is incorporated into the surface of the semiconductor material (i.e., the first surface 25). In some embodiments, the modified first surface 60 contains a silicon compound. In some embodiments, the modified first surface 60 contains titanium and silicon. In some embodiments, the modified first surface 60 consists essentially of TiSi2.

[0049] In some embodiments, process 210 includes an annealing process. In some embodiments, the modified first surface 60 contains TiSi-C49. In some embodiments, forming the modified first surface 60 includes annealing the substrate at a temperature in the range of about 500 °C to about 700 °C to form TiSi-C49. In some embodiments, the annealing process is performed for more than about 1 minute. In some embodiments, forming the modified first surface 60 includes laser annealing the substrate at a temperature in the range of about 800 °C to about 1000 °C to form TiSi-C49. In some embodiments, the laser annealing process is millisecond laser annealing.

[0050] In some embodiments, the modified first surface 60 contains TiSi-C54. In some embodiments, forming the modified first surface 60 includes annealing the substrate at a temperature in the range of about 700 °C to about 900 °C to form TiSi-C54. In some embodiments, the annealing process is performed for more than about 1 minute. In some embodiments, forming the modified first surface 60 includes laser annealing the substrate at a temperature in the range of about 1000 °C to about 1200 °C to form TiSi-C54. In some embodiments, the laser annealing process is millisecond laser annealing.

[0051] The disclosure of this specification has been described with reference to specific embodiments, but these embodiments are to be understood as merely illustrative examples of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatuses of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

1. A selective deposition method comprising: providing a substrate having a first semiconductor surface and a second dielectric surface; exposing the substrate to a blocking compound to selectively form a blocking layer on the second dielectric surface with respect to the first semiconductor surface; exposing the substrate to a titanium precursor to selectively deposit a Ti-containing layer on the first semiconductor surface with respect to the second dielectric surface; exposing the substrate to a germanium precursor to selectively deposit a Ge-containing layer on the first semiconductor surface with respect to the second dielectric surface; exposing the substrate to a silicon precursor to selectively deposit a Si-containing layer on the first semiconductor surface with respect to the second dielectric surface; and heating the substrate to form a modified first semiconductor surface containing titanium and silicon The method includes.

2. The method according to claim 1, wherein the substrate includes a finFET structure.

3. The method according to claim 2, wherein the finFET structure includes a silicon surface and includes source and drain terminals.

4. The blocking compound is a blocking agent of the general formula R ３ Si-X, wherein each R is independently C1-C4 alkyl and X is any leaving group, the method according to claim 1.

5. The blocking agent consists essentially of formula I: The method according to claim 4, which consists of the compound of.

6. The method according to claim 5, wherein the substrate is exposed to the blocking compound at a temperature in the range of about 250 ° C to about 450 ° C.

7. The method according to claim 1, wherein the titanium precursor includes a species containing at least one halide ligand.

8. The method according to claim 1, wherein the titanium precursor includes a species containing at least one amine ligand.

9. wherein the amine ligand is of the general formula -NR ２ and each R is independently selected from H, a C1-C4 alkyl group, or a trimethylsilyl group, the method according to claim 8.

10. The method according to claim 9, wherein the titanium precursor consists essentially of tetrakis(ethylmethylamide)titanium.

11. The method according to claim 1, wherein the titanium precursor includes a species containing at least one oxo ligand.

12. The method according to claim 1, wherein exposing the substrate to the titanium precursor further includes separately exposing the substrate to reactants.

13. The method according to claim 12, further including exposing the substrate to plasma.

14. The method according to claim 1, wherein the Ti-containing layer includes a titanium alloy.

15. The modified first semiconductor surface consists essentially of TiSi ２ The method according to claim 1, comprising:

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