Methods, systems, and apparatus for forming metal sulfide layers

Abstract

A method, system and apparatus are disclosed for depositing a threshold voltage offset layer comprising an oxygen-free metal sulfide on a substrate, where the depositing further includes providing a substrate having a surface within a reaction chamber, a) providing an oxygen-free precursor comprising a metal to the reaction chamber to contact the surface, b) providing an oxygen-free sulfur-containing reactant to the reaction chamber to contact the surface, and c) depositing the oxygen-free sulfur-containing reactant on the substrate. C) purging the reaction chamber and repeating operations a), b) or c), or any combination thereof, until a predetermined thickness of the threshold voltage offset layer is deposited on the surface.

Description

Technical Field

[0001] The present disclosure relates generally to the field of semiconductor processing methods and systems, and to the field of electronic devices, and in particular, to methods and systems suitable for forming layers containing metal sulfides. Background Art

[0002] The reduction in size of semiconductor devices, such as complementary metal oxide semiconductor (CMOS) devices, has led to significant improvements in the speed and density of integrated circuits. However, conventional device scaling techniques face significant challenges at future technology nodes.

[0003] For example, one challenge is to find suitable conductive materials for use as gate electrodes, especially threshold voltage shifting materials in large-scale CMOS devices. Therefore, there is a need for improved materials for gate electrodes. Specifically, such materials can include threshold voltage shifting layers and can be used for threshold voltage tuning. Summary of the invention

[0004] This summary is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the detailed description of the example embodiments disclosed below. This summary is not intended to necessarily identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0005] In one aspect, a method includes depositing a threshold voltage shift layer including a metal sulfide on a substrate, wherein the deposition further includes a) providing a substrate having a surface in a reaction chamber, b) providing an oxygen-free metal precursor to the reaction chamber to contact the surface, c) providing an oxygen-free sulfur-containing reactant to the reaction chamber to contact the surface, d) purging the reaction chamber, and repeating operations b), c) or d) or any combination thereof until a threshold voltage shift layer of a predetermined thickness is deposited on the surface.

[0006] In certain examples, the method may also include where the surface includes an interlayer material, and the threshold voltage shift layer is deposited directly onto the interlayer material surface in a dipole first pattern.

[0007] In some examples, the method can also include where the surface includes a high-k material, and the threshold voltage shifting layer is deposited directly onto the high-k material surface in a dipole final pattern.

[0008] In various examples, the method may also include where the metal includes titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), aluminum (Al), scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr) or a combination thereof.

[0009] In certain examples, the method may further include wherein the oxygen-free precursor is a metal cyclopentadienyl compound and the metal includes scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La), or strontium (Sr).

[0010] In some examples, the method may further include where the oxygen-free precursor is a metal alkylamide compound, and the metal includes titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), or aluminum (Al).

[0011] In various examples, the method may further include where the oxygen-free precursor is a metal amidine compound, and the metal includes scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La), or strontium (Sr).

[0012] In certain examples, the method may also include where the sulfur-containing reactant includes H 2 S.

[0013] In certain embodiments, the method may further include wherein the sulfur-containing reactant compound is of the formula HS(CRR')xSH, wherein R and R' are independently selected from hydrogen (H), methyl (Me), ethyl (Et), n-propyl (nPr), and x is an integer from 1 to 12.

[0014] In various embodiments, the method may also include a sulfur-containing reactant compound having the formula S(SiRR'R")2, wherein R, R' and R" are independently selected from H, Me, Et, nPr, isopropyl (iPr), tert-butyl (tBu), n-butyl (nBu), sec-butyl (sec-Bu) and isobutyl (iso-Bu).

[0015] In certain examples, the method may further include wherein the sulfur-containing reactant compound is of the formula S2RR', wherein R and R' are independently selected from Me, Et, nPr, iPr, tBu, nBu, sec-Bu, and iso-Bu.

[0016] In various embodiments, the method may further include wherein the sulfur-containing reactant compound is of the formula RSH, wherein R is a straight or branched chain alkyl group containing 1 to 10 carbon atoms.

[0017] In certain examples, the method may also include where the sulfur-containing reactant includes only sulfur atoms.

[0018] In some examples, the method may also include where the sulfur-containing reactant includes sulfur and a halogen.

[0019] In some examples, the method may also include wherein the metal amidine compound has the following formula (Formula 1):

[0020]

[0021] wherein M is a metal, R and R' are independently any branched alkyl, unbranched alkyl, cyclic alkyl or non-cyclic alkyl containing 1-10 carbon atoms or a combination thereof, R" is hydrogen, dimethylamino, diethylamino, ethylmethylamino or an alkyl containing 1-6 carbon atoms, wherein R and R' are independently selected from isopropyl, tert-butyl, sec-butyl and tert-amyl, and wherein R" is hydrogen or methyl.

[0022] In certain examples, the method may also include wherein the sulfur-containing reactant is HS(CH2)2SH or HS(CH)3SH.

[0023] In various examples, the method may also include where the sulfur-containing reactant is S(SiMe3)2 or S(SiEt3)2.

[0024] In certain examples, the method may also include where the sulfur-containing reactant is S2Me2, S2Et2, or S2(tBu)2.

[0025] In order to summarize the present disclosure and the advantages achieved relative to the prior art, certain objects and advantages of the present disclosure have been described above. Of course, it should be understood that according to any specific embodiment or example of the present disclosure, not all of these objects or advantages may be achieved. Thus, for example, those skilled in the art will recognize that the examples disclosed herein can be implemented in a manner that achieves or optimizes one advantage or a group of advantages taught or suggested herein, without necessarily achieving other objects or advantages taught or suggested herein. All of these examples are within the scope of the present disclosure. These and other embodiments will become apparent to those skilled in the art by the following detailed description of certain examples with reference to the accompanying drawings, and the present disclosure is not limited to any specific example discussed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A more complete understanding of embodiments of the present disclosure may be obtained by referring to the detailed description and claims when considered in conjunction with the following illustrative drawings.

[0027] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0028] FIG. 2A to FIG. 2C An exemplary structure according to an embodiment of the present disclosure is shown.

[0029] Figure 3 An exemplary structure according to an embodiment of the present disclosure is shown.

[0030] Figure 4 An exemplary structure according to an embodiment of the present disclosure is shown.

[0031] Figure 5 Reactor systems according to additional exemplary embodiments of the present disclosure are shown.

[0032] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the size of some elements in the drawings may be exaggerated relative to other elements to help improve the understanding of the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] The detailed description of various examples herein refers to the accompanying drawings, which illustrate exemplary examples by way of illustration. Although these exemplary examples are described in sufficient detail to enable those skilled in the art to practice the present disclosure, it should be understood that other examples may be implemented without departing from the spirit and scope of the present disclosure, and logical, chemical and / or mechanical changes may be made. Therefore, the detailed description here is only for the purpose of illustration, not for limitation. For example, the steps described in any method or process description may be performed in any combination and / or order, and are not limited to the presented combination and / or order. In addition, one or more steps from one of the disclosed methods or processes may be combined with one or more steps from another disclosed method or process in any suitable combination and / or order. In addition, any function or step may be outsourced to one or more third parties or performed by a third party. In addition, any reference to the singular includes plural examples, and any reference to more than one component may include a singular example.

[0034] Although certain embodiments and examples are disclosed below, those skilled in the art will appreciate that the disclosure extends beyond the specifically disclosed examples and / or uses of the disclosure and obvious modifications and equivalents thereof. Therefore, it is intended that the scope of the disclosure should not be limited by the specific examples described herein.

[0035] The illustrations presented herein are not meant to be actual views of any particular material, apparatus, structure, or device, but are merely representations of examples used to describe the present disclosure.

[0036] As used herein, the term "atomic layer deposition" (ALD) may refer to a vapor deposition process in which a deposition cycle, preferably a plurality of consecutive deposition cycles, is performed in a processing chamber. Typically, during each cycle, a precursor is chemically adsorbed to a deposition surface (e.g., a substrate surface or a previously deposited underlying surface, such as material from a previous ALD cycle) to form a monolayer or sub-monolayer that is not easily reacted with additional precursors (i.e., a self-limiting reaction). Thereafter, if desired, a reactant (e.g., another precursor or a reactive gas) may be subsequently introduced into the processing chamber for converting the chemically adsorbed precursor into the desired material on the deposition surface. Typically, the reactant is capable of further reacting with the precursor. In addition, a purge step may also be utilized during each cycle to remove excess precursor from the processing chamber and / or excess reactant and / or reaction byproducts from the processing chamber after the chemically adsorbed precursor is converted. In addition, the term "atomic layer deposition" as used herein is also meant to include processes designated by related terms, such as, "chemical vapor atomic layer deposition", "atomic layer epitaxy" (ALE), molecular beam epitaxy (MBE), gas source MBE or organometallic MBE, and chemical beam epitaxy when performed with alternating pulses of precursor composition, reaction gas and purge gas (e.g., an inert carrier gas).

[0037] As used herein, the term "chemical vapor deposition" (CVD) may refer to any process in which a substrate is exposed to one or more volatile precursors that react and / or decompose on the substrate surface to produce the desired deposit.

[0038] In addition, in the present disclosure, any two numbers of a variable may constitute a feasible range for the variable, and any range indicated may include or exclude endpoints. In addition, any values ​​of the variables indicated (regardless of whether they are expressed as "about") may refer to exact values ​​or approximate values, and include equivalents, and may refer to average values, median values, representative values, majority values, etc. In addition, in the present disclosure, the terms "including", "consisting of" and "having" may independently refer to "generally or broadly including", "comprising", "essentially consisting of" or "consisting of" in some examples. In the present disclosure, the meaning of any definition does not necessarily exclude the common and customary meanings in some examples.

[0039] The present disclosure may include methods, systems, and devices for forming semiconductor structures including threshold voltage shift layers. The threshold voltage shift layers may enhance the performance of semiconductor devices by adjusting the effective work function (EWF) of metal oxide semiconductor (MOS) devices.

[0040] In some embodiments, a threshold voltage shift layer may be formed, for example, by a deposition process, on or directly on a gate dielectric of a metal oxide semiconductor (MOS) device, and the properties of the threshold voltage shift layer (including but not limited to material composition, thickness, and deposition method) may change the energy band alignment in the MOS device to provide a device with preferred operating performance. Conventional threshold shift layers contain oxygen and may produce SiOx at the interface, which increases the equivalent oxide thickness (EOT) of the device. Therefore, in some embodiments, as a way to control the effective oxide thickness to improve the electrical performance of the final device, a threshold voltage shift layer made of an oxygen-free material and substantially oxygen-free or having a reduced oxygen content may be desirable.

[0041] As described in more detail below, various embodiments of the present disclosure provide methods for forming structures and / or devices suitable for various applications. Exemplary methods can be used, for example, to form gate electrodes, and / or to form metal sulfide layers suitable for metal oxide semiconductor (MOS) applications (e.g., as work function layers and / or threshold voltage shift layers, dipole or flat band shifters), such as in the formation of complementary MOS (CMOS) devices, as etch stop layers, and / or as barrier or liner layers (e.g., in FEOL, MEOL, and BEOL processing). For example, the metal sulfide layer can be used to form logic devices, dynamic random access memory (DRAM), three-dimensional NAND devices, p-metal layer gates as logic devices, p-dipole layers as logic devices, etc. However, unless otherwise stated, the present invention is not necessarily limited to these examples.

[0042] In the present disclosure, "gas" may include materials that are gaseous at normal temperature and pressure (NTP), evaporated solids and / or evaporated liquids, and may be composed of a single gas or a gas mixture depending on the context. Gases other than process gases, i.e., gases that are not introduced through gas distribution components, other gas distribution devices, etc., may be used, for example, to seal reaction spaces, and may include sealing gases, such as rare gases. In some cases, the term "precursor" may refer to a compound that participates in a chemical reaction that produces another compound, particularly a compound that constitutes a membrane matrix or a main skeleton of a membrane; the term "reactant" may be used interchangeably with the term precursor. The term "inert gas" may refer to a gas that does not participate in a chemical reaction and / or does not become a part of the membrane matrix to a perceptible degree. Exemplary inert gases include helium, argon, and any combination thereof. In some cases, the inert gas may include nitrogen and / or hydrogen.

[0043] As used herein, the term "substrate" may refer to any one or more underlying materials that may be used to form or on which a device, circuit, or film may be formed. The substrate may include a bulk material, such as silicon (e.g., single crystal silicon), other Group IV materials, such as germanium, or other semiconductor materials, such as Group II-VI or Group III-V semiconductor materials, and may include one or more layers overlying or underlying the bulk material. In addition, the substrate may include various features, such as depressions, protrusions, etc., formed in or on at least a portion of the substrate layer. For example, the substrate may include a bulk semiconductor material and a layer of insulating or dielectric material overlying at least a portion of the bulk semiconductor material.

[0044] As used herein, the terms "film" and / or "layer" may refer to any continuous or discontinuous structure and material, such as a material deposited by the methods disclosed herein. For example, a film and / or layer may include a two-dimensional material, a three-dimensional material, nanoparticles, or even a partial or complete molecular layer or a partial or complete atomic layer or clusters of atoms and / or molecules. A film or layer may include a material or layer having pinholes, which may be at least partially continuous.

[0045] As used herein, a "structure" may be or include a substrate as described herein. A structure may include one or more layers covering a substrate, such as one or more layers formed according to a method as described herein. A device portion may be or include a structure.

[0046] The term "cyclic deposition process" or "cyclic deposition process" may refer to the sequential introduction of precursors (and / or reactants) into a reaction chamber to deposit layers on a substrate, and includes processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes including an ALD component and a cyclic CVD component.

[0047] As used herein, a “metal sulfide layer” or a “layer including a metal sulfide” may be a material layer represented by a chemical formula including a metal and sulfur.

[0048] As used herein, "oxygen-free metal sulfide" or "oxygen-free metal sulfide layer" can be an oxygen-free or substantially oxygen-free metal sulfide layer, including less than about 7% oxygen, or less than about 5% oxygen, or less than about 4% oxygen, or less than about 3% oxygen, or less than about 2% oxygen, or less than about 1% oxygen, or less than about 0.1% oxygen ("about" herein means ±0.5%).

[0049] In some examples, the metal component of the metal sulfide layer may include titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), aluminum (Al), scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr), or a combination thereof.

[0050] As used herein, “oxygen-free metal precursor” includes a gas or material that can be changed into a gaseous state, and may be represented by a chemical formula that does not contain oxygen.

[0051] As used herein, "oxygen-free sulfur-containing reactant" includes a gas or material that can be changed into a gaseous state and that can be represented by a chemical formula that includes sulfur but does not include oxygen.

[0052] In addition, in the present disclosure, any two numbers of a variable may constitute a feasible range of the variable, and any range indicated may include or exclude endpoints. In addition, any values ​​of the variables indicated (regardless of whether they are expressed as "about") may refer to exact values ​​or approximate values, and include equivalents, and may refer to average values, median values, representative values, majority values, etc. In addition, in the present disclosure, the terms "including", "consisting of" and "having" independently refer to "usually or broadly including", "comprising", "essentially consisting of" or "consisting of" in some embodiments. In the present disclosure, the meaning of any definition does not necessarily exclude the common and customary meanings in some embodiments.

[0053] Turning now to the accompanying drawings, Figure 1 A method 100 is shown according to an exemplary embodiment of the present disclosure. The method 100 can be used, for example, to form a structure including a metal sulfide layer (e.g., metal sulfide layer 208), which can be oxygen-free or substantially oxygen-free. The metal sulfide layer can be used in the formation of a device (e.g., the device mentioned herein). However, unless otherwise stated, the method is not limited to these applications.

[0054] The method 100 includes the steps of providing a substrate within a reaction chamber of a reactor (step 102 ), and depositing a layer including a metal sulfide layer onto a surface of the substrate using a cyclic deposition process (step 104 ).

[0055] During step 102, a substrate is provided within a reaction chamber. The reaction chamber used during step 102 may be or include a reaction chamber of a chemical vapor deposition reactor system configured to perform a cyclic deposition process. The reaction chamber may be a stand-alone reaction chamber or part of a combination tool.

[0056] Step 102 may include heating the substrate to a desired deposition temperature within the reaction chamber. In some embodiments of the present disclosure, step 102 includes heating the substrate to a temperature below 800° C. For example, in some embodiments of the present disclosure, heating the substrate to the deposition temperature may include heating the substrate to a temperature between about 20° C. and about 800° C., between about 100° C. and about 400° C., between about 20° C. and about 300° C., or between about 20° C. and about 200° C.

[0057] In addition to controlling the temperature of the substrate, the pressure in the reaction chamber may also be adjusted. For example, in some embodiments of the present disclosure, during step 102, the pressure in the reaction chamber may be less than 760 Torr, or between 0.2 Torr and 760 Torr, between about 1 Torr and 100 Torr, or between about 1 Torr and 10 Torr.

[0058] During step 104, a metal sulfide layer is deposited onto the surface of the substrate using a cyclic deposition process. As described above, the cyclic deposition process may include cyclic CVD, ALD, or a hybrid cyclic CVD / ALD process. For example, in some embodiments, the growth rate of a particular ALD process may be lower than that of a CVD process. One way to increase the growth rate may be to operate at a deposition temperature higher than the deposition temperature typically employed in an ALD process, resulting in certain portions of a chemical vapor deposition process, but still utilizing a sequential introduction of reactants. Such a process may be referred to as cyclic CVD. In some embodiments, a cyclic CVD process may include introducing two or more reactants into a reaction chamber, wherein there may be a period of overlap between the two or more reactants in the reaction chamber, resulting in an ALD component of the deposition and a CVD component of the deposition. This is referred to as a hybrid process.

[0059] According to further examples, the cyclic deposition process can include a pulse and / or flow of a metal precursor (step 106) and / or a pulse and / or flow of a sulfur-containing reactant (step 108) into a reaction chamber. Such pulses and / or flows of a metal precursor (step 106) and / or a sulfur-containing reactant (step 108) can be sequential, simultaneous, cyclical, and / or repeated, and the claimed subject matter is not limited thereto. In some examples, the metal precursor can be an oxygen-free metal precursor. Similarly, the sulfur-containing reactant can be an oxygen-free sulfur-containing reactant.

[0060] As specific examples, the metal in the metal precursor may include titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), aluminum (Al), scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr) or a combination thereof.

[0061] In some examples, the oxygen-free metal precursor may include a metal cyclopentadienyl compound. In some examples, the metal of the metal cyclopentadienyl compound may include scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr) or a combination thereof.

[0062] In other specific examples, the oxygen-free metal precursor may include a metal alkylamide compound. In some examples, the metal of the metal alkylamide compound may include titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta) or aluminum (Al), or a combination thereof.

[0063] In other examples, the oxygen-free precursor is a metal amidine compound. In some examples, the metal of the metal amidine compound may include scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr), or a combination thereof.

[0064] In certain examples, the metal amidine compound has the following formula (Formula 1):

[0065]

[0066] wherein: M is a metal; R and R' are independently any branched alkyl, unbranched alkyl, cyclic alkyl or non-cyclic alkyl containing 1-10 carbon atoms or a combination thereof; R" is hydrogen, dimethylamino, diethylamino, ethylmethylamino or an alkyl containing 1-6 carbon atoms.

[0067] Still referring to the metal amidine compound of Formula 1, in one example, R and R′ can be independently selected from isopropyl, tert-butyl, sec-butyl, and tert-amyl.

[0068] Still referring to the metal amidine compound of Formula 1, in one example, R" can be hydrogen or methyl.

[0069] In certain examples, the sulfur-containing reactant may be oxygen-free and may include a compound having the formula HS(CRR')xSH, wherein R and R' are independently selected from hydrogen (H), methyl (Me), ethyl (Et), n-propyl (nPr), and wherein x is an integer from 1 to 12.

[0070] Exemplary sulfur-containing reactants of this type may be HS(CH2)2SH or HS(CH)3SH.

[0071] In certain examples, the sulfur-containing reactant can be oxygen-free and can include a compound having the formula S(SiRR'R")2, wherein R, R' and R" are independently selected from H, Me, Et, nPr, isopropyl (iPr), tert-butyl (tBu), n-butyl (nBu), sec-butyl (sec-Bu) and isobutyl (iso-Bu).

[0072] Exemplary sulfur-containing reactants of this type may be S(SiMe3)2 or S(SiEt3)2.

[0073] In certain examples, the sulfur-containing reactant may be oxygen-free and may include a compound having the formula S2RR', wherein R and R' are independently selected from Me, Et, nPr, iPr, tBu, nBu, sec-Bu, and iso-Bu.

[0074] Exemplary sulfur-containing reactants of this type may be S2Me2, S2Et2, or S2(tBu)2.

[0075] In certain examples, the sulfur-containing reactant may be oxygen-free and may include a compound having the formula RSH, where R is a straight or branched chain alkyl group containing 1 to 10 carbon atoms.

[0076] Exemplary sulfur-containing reactants of this type may be tBuSH or iPrSH.

[0077] In certain examples, the sulfur-containing reactant may be oxygen-free and may include compounds having only sulfur atoms.

[0078] Exemplary sulfur-containing reactants of this type may be S4 or S8.

[0079] In some examples, the sulfur-containing reactant may be oxygen-free and may include a compound having sulfur and a halogen. In some examples, the halogen may be chlorine. In some examples, the sulfur-containing reactant may be SCl2 or S2Cl2.

[0080] Exemplary sulfur-containing reactants including compounds having sulfur and halogens may contain SS bonds.

[0081] In one example, hydrogen sulfide (H 2 S) may be the oxygen-free sulfur-containing reactant.

[0082] The cyclic deposition process may include (e.g., separately and / or sequentially) providing an oxygen-free precursor comprising a metal precursor to the reaction chamber (step 106), and providing an oxygen-free sulfur-containing reactant to the reaction chamber (step 108). A purge may be performed at any point during the cyclic process, for example, to remove byproducts (step 110). The purge step 110 may be performed before or after providing one or more precursors and / or reactants to the chamber.

[0083] In some cases, two or more precursors and / or two or more reactants can flow to the reaction chamber so that the two or more precursors and / or two or more reactants overlap within the reaction chamber. For example, one or more oxygen-free metal precursors and / or one or more sulfur-containing reactants can co-flow to the reaction chamber.

[0084] In the case of a thermal cycle deposition process, the duration of the step of providing the reactant to the reaction chamber can be relatively long to allow the reactant to react with the precursor or its derivative. For example, the duration can be greater than or equal to 0.1 seconds, or greater than or equal to 60 seconds, or between about 0.1 and 60 seconds.

[0085] As part of step 104, the reaction chamber may be purged (step 110) using a vacuum and / or an inert gas, for example to mitigate gas phase reactions between reactants and to achieve self-saturating surface reactions—for example in the case of ALD. Additionally or alternatively, the substrate may be moved to contact the first gas phase reactant and the second gas phase reactant, respectively. Excess chemicals and reaction byproducts, if any, may be removed from the substrate surface or reaction chamber before the substrate is contacted with the next reactive chemical, for example by purging the reaction space or by moving the substrate. The reaction chamber may be purged after the step of providing the precursor to the reaction chamber and / or after the step of providing the reactant to the reaction chamber.

[0086] In some embodiments of the present disclosure, method 100 includes repeating a unit deposition cycle, the cycle comprising (1) providing one or more oxygen-free metal precursors to a reaction chamber, and (2) providing an oxygen-free sulfur-containing reactant to the reaction chamber, with an optional purge or move step after step (1) and / or step (2). The deposition cycle can be repeated one or more times based on, for example, the desired thickness of the metal sulfide layer. For example, if the thickness of the metal sulfide layer is less than the thickness required for a particular application, then the steps of providing the precursor to the reaction chamber and providing the reactant to the reaction chamber can be repeated one or more times. Once the metal sulfide layer has been deposited to the desired thickness, the substrate can be subjected to additional processes to form a device structure and / or device.

[0087] In some embodiments, in / on structures having an aspect ratio (height / width) greater than about 2, greater than about 5, greater than about 10, greater than about 25, greater than about 50, greater than about 100, or between about 10 and 100, or between about 5 and 25, the step coverage of the metal sulfide layer is equal to or greater than about 50%, or greater than about 80%, or greater than about 90%, or about 95%, or about 98%, or about 99% or more.

[0088] The growth rate of the metal sulfide layer can be relatively low—e.g., less than 3 angstroms / cycle, between about 0.2 and 3 angstroms / cycle, or about 0.1 to about 1 angstrom / cycle. The relatively low growth rate can contribute to the desired precision of film thickness and / or film thickness uniformity. Where the metal sulfide layer is in a threshold voltage shift layer, such layers can work even if they are not fully closed because their total thickness can be less than one angstrom. Thus, in the case of such thin layers, low growth rates and high precision can be advantageous.

[0089] Figure 2A A structure / portion of a device 200 according to an additional example of the present disclosure is shown. The device or structure 200 includes a substrate 202, a dielectric or insulating material 205, and a metal sulfide layer 208. In an example, the metal sulfide layer 208 is a threshold voltage shifting layer. In the example shown, the structure 200 also includes an additional conductive layer 210.

[0090] Substrate 202 may be or include any substrate material described herein.

[0091] The dielectric or insulating material 205 may include one or more dielectric or insulating material layers. For example, the dielectric or insulating material 205 may include an interface layer 204 and a high-k material 206 deposited on the interface layer 204. The metal sulfide layer 208 is deposited directly onto the surface of the high-k material 206 in a dipole final pattern.

[0092] In some cases, the interface layer 204 may not be present or may not be present to an appreciable extent. The interface layer 204 may include an oxide, such as silicon oxide, which may be formed on the surface of the substrate 202 using, for example, a chemical oxidation process or an oxide deposition process. The high-k material 206 may be or include, for example, a metal oxide having a dielectric constant greater than about 7. In some embodiments, the dielectric constant of the high-k material is higher than the dielectric constant of silicon oxide. Exemplary high-k materials include one or more of hafnium oxide (HfO2), tantalum oxide (Ta2O5), zirconium oxide (ZrO2), titanium oxide (TiO2), hafnium silicate (HfSiOx), aluminum oxide (Al2O3), lanthanum oxide (La2O3), and mixtures / stacks including one or more of such layers.

[0093] In one example, the metal sulfide layer 208 can be formed according to the methods described herein. Because the metal sulfide layer 208 is formed using a cyclic deposition process, the concentration of sulfur and / or metal and / or other components in the metal sulfide layer 208 can be varied from the bottom of the metal sulfide layer 208 to the top of the metal sulfide layer 208 by, for example, controlling the amount of oxygen-free metal precursor and / or oxygen-free sulfur-containing reactant and / or the corresponding pulse time during one or more deposition cycles. In some cases, the metal sulfide layer 208 can have a stoichiometric composition. The work function and other properties of the metal sulfide layer 208 can be changed by changing the amount of sulfur and / or metal and / or other compounds in the layer or in the deposition cycle.

[0094] In an example, the metal sulfide layer 208 may include impurities, such as halides, hydrogen and / or oxygen, alone or in combination, in an amount less than 10 atomic %, 5 atomic %, less than 1 atomic %, less than 0.2 atomic %, less than 0.1 atomic % or less than 0.05 atomic %.

[0095] The thickness of the metal sulfide layer 208 can vary depending on the application. For example, the desired or predetermined thickness of the metal sulfide layer 208 can be less than 10 nm or about 0.05 nm to about 10 nm, or about 0.06 nm to about 5 nm, or about 0.07 nm to about 5 nm, or about 0.08 nm to about 4 nm, or about 0.09 nm to about 3 nm, or about 0.1 nm to about 2 nm. In one example, the metal sulfide layer 208 can be relatively thin, which may be desirable for many applications including work function and / or threshold voltage shifting layers. In one example, the metal sulfide layer 208 can form a non-continuous functional layer that is operable to perform voltage threshold adjustment. In some cases, the thickness of the metal sulfide layer 208 can be greater than 2 nm—for example, when the metal sulfide layer 208 is used as a barrier layer or liner.

[0096] The thickness and / or composition of the metal sulfide layer 208 can be manipulated to obtain a desired shift in work function and / or threshold voltage. In one example, the shifted work function of the metal sulfide layer 208 can be >4.6 eV, >4.7 eV, >4.8 eV, >4.9 eV, >4.95 eV, or >5.0 eV. Using the metal sulfide layer 208 described herein, the work function value of the device can be shifted by about 30 meV to about 400 meV, or about 30 meV to about 200 meV, or about 50 meV to about 100 meV.

[0097] Additionally or alternatively, the metal sulfide layer 208 may form a continuous film having a thickness of <5 nm, <4 nm, <3 nm, <2 nm, <1.5 nm, <1.2 nm, <1.0 nm, or <0.9 nm—eg, using method 100. The metal sulfide layer 208 may be relatively smooth, with relatively low grain boundary formation.

[0098] In some cases, the metal sulfide layer 208 may additionally or alternatively be formed directly on the substrate 202 beneath the dielectric or insulating material 205 (which may include various layers and / or topologies), such as Figure 2B As shown in an additional example according to the present disclosure, a device or structure 220 includes a substrate 202 , a dielectric or insulating material 205 including an interface layer 204 , and a high-k material 206 deposited on the interface layer 204 . The structure 220 also includes an additional conductive layer 210 . The interface layer 204 is deposited on the metal sulfide layer 208 .

[0099] In some cases, according to additional examples of the present disclosure, such as Figure 2C As shown, a metal sulfide layer 208 may additionally or alternatively be formed between the interface layer 204 and the high-k material 206 and / or between layers of the high-k material 206 . Figure 2C Similar to Figure 2A and 2BThe structure is shown, except that a threshold metal sulfide layer 208 is located between the interface layer 204 and the high-k material 206. The metal sulfide layer 208 is deposited directly onto the surface of the interface layer 204 in a dipole first pattern.

[0100] Device or structure 230 includes substrate 202, metal sulfide layer 208 deposited directly on interface layer 204, and high-k material 206 deposited on metal sulfide layer 208. Structure 230 also includes an additional conductive layer 210. In addition, metal sulfide layer 208 may be deposited and at least partially removed, such that the resulting structure may no longer include metal sulfide layer 208 or include a smaller amount of metal sulfide layer than was initially formed on the structure.

[0101] Figure 3 Another exemplary structure 300 according to an example of the present disclosure is shown. The device or structure 300 includes a substrate 302, a dielectric or insulating material 304, and a metal sulfide layer 306. In an example, the metal sulfide layer 306 includes a threshold voltage shift layer. In the example shown, the structure 300 also includes an additional conductive layer 312. The substrate 302, the dielectric or insulating material 304, the metal sulfide layer 306, and the additional conductive layer 312 can be the same or similar to the substrate 202, the dielectric or insulating material 205, the metal sulfide layer 208, and the conductive layer 210. Similar to the above, the metal sulfide layer 306 can be additionally or alternatively formed on the substrate 302 (which can include various layers and / or topologies) and / or below the insulating material 304, between the interface layer 308 and the high-k material 310, and / or between layers of the high-k material 310. Additionally, the metal sulfide layer 306 may be deposited and at least partially removed such that the resulting structure may no longer include the metal sulfide layer 306 or include a smaller amount of the metal sulfide layer than was initially formed on the structure.

[0102] In the example shown, substrate 302 includes source region 314, drain region 316, and channel region 318. Although illustrated as a horizontal structure, structures and devices according to examples of the present disclosure may include vertical and / or three-dimensional structures and devices, such as FinFET devices.

[0103] Figure 4 Another structure 400 according to an example of the present disclosure is shown. The structure 400 is suitable for use in a gate-all-around field effect transistor (GAA FET) (also known as a lateral nanowire FET) device, among other things.

[0104] In the example shown, structure 400 includes semiconductor material 402, dielectric material 404, metal sulfide layer 406, and conductive layer 408. Structure 400 can be formed on a substrate, including any substrate material described herein. In an example, metal sulfide layer 406 is a threshold voltage shifting layer.

[0105] The semiconductor material 402 may include any suitable semiconductor material. For example, the semiconductor material 402 may include a Group IV, Group III-V, or Group II-VI semiconductor material. For example, the semiconductor material 402 includes silicon.

[0106] Dielectric material 404, metal sulfide layer 406, and conductive layer 408 may be the same or similar to dielectric or insulating material 205, metal sulfide layer 208, and conductive layer 210 described above. According to further examples of the present disclosure, metal sulfide layer 406 may be formed over semiconductor material 402 and / or under dielectric material 404.

[0107] Figure 5 A system 500 is shown according to another exemplary embodiment of the present disclosure. The system 500 can be used to perform the methods described herein and / or form part of the structures or devices described herein.

[0108] In the illustrated example, system 500 includes one or more reaction chambers 502 , a precursor gas source 504 , a reactant gas source 506 , a purge gas source 508 , an exhaust source 510 , and a controller 512 .

[0109] The reaction chamber 502 may include any suitable reaction chamber, such as an ALD or CVD reaction chamber.

[0110] Precursor gas source 504 may include a container and one or more oxygen-free metal precursors as described herein - alone or mixed with one or more carrier gases (e.g., inert gases). Reactant gas source 506 may include a container and one or more oxygen-free sulfur-containing reactants as described herein - alone or mixed with one or more carrier gases. Purge gas source 508 may include one or more inert gases as described herein. Although three gas sources 504-508 are shown, system 500 may include any suitable number of gas sources. Gas sources 504-508 may be coupled to reaction chamber 502 via pipelines 514-518, which may each include a flow controller, a valve, a heater, etc.

[0111] Exhaust source 510 may include one or more vacuum pumps.

[0112] Controller 512 includes electronic circuits and software to selectively operate valves, manifolds, heaters, pumps and other components included in system 500. Such circuits and components are used to introduce precursors, reactants and purge gases from corresponding sources 504-508. Controller 512 can control the timing of gas pulse sequences, the temperature of substrates and / or reaction chambers, the pressure in the reaction chamber, and various other operations to provide correct operation of system 500. Controller 512 can include control software to control the flow of precursors, reactants and purge gases into and out of reaction chamber 502 by electrically or pneumatically controlling valves. Controller 512 may include modules that perform certain tasks, such as software or hardware components, such as FPGA or ASIC. Modules can be advantageously configured to reside on an addressable storage medium of the control system and configured to perform one or more processes.

[0113] Other configurations of the system 500 are possible, including different numbers and types of precursor and reactant sources and purge gas sources. In addition, it should be understood that there are many arrangements of valves, conduits, precursor sources, and purge gas sources that can be used to achieve the goal of selectively supplying gases into the reaction chamber 502. In addition, as a schematic representation of the system, many components have been omitted for simplicity of illustration, and these components may include, for example, various valves, manifolds, purifiers, heaters, containers, vents, and / or bypasses.

[0114] During operation of the reactor system 500, a substrate 590, such as a semiconductor wafer, is transferred from, for example, a substrate handling system to the reaction chamber 502. Once the substrate is transferred to the reaction chamber 502, one or more gases, such as precursors, reactants, carrier gases, and / or purge gases, from gas sources 504, 508 are introduced into the reaction chamber 502.

[0115] The exemplary embodiments disclosed above do not limit the scope of the present invention, as these embodiments are merely examples of embodiments of the present invention, and the scope of the present invention is defined by the attached claims and their legal equivalents. Any equivalent embodiments are within the scope of the present invention. In fact, various modifications of the present disclosure, such as alternative useful combinations of the described elements, in addition to those shown and described herein, will become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the attached claims. Although exemplary examples of the present disclosure are set forth herein, it should be understood that the present disclosure is not limited thereto. Various modifications, changes, and enhancements may be made to the systems and methods set forth herein without departing from the spirit and scope of the present disclosure.

[0116] The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems, components and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. A method comprising: depositing a threshold voltage shifting layer comprising a metal sulfide on a substrate, wherein the depositing further comprises: a) providing a substrate having a surface in a reaction chamber; b) providing an oxygen-free precursor comprising a metal to the reaction chamber to contact the surface; c) providing an oxygen-free sulfur-containing reactant to the reaction chamber to contact the surface; d) purging the reaction chamber; and Operations b), c) or d) or any combination thereof are repeated until a threshold voltage shifting layer of a predetermined thickness is deposited on the surface.

2. The method according to claim 1, wherein: The surface includes an interlayer material, and the threshold voltage shift layer is deposited directly onto the interlayer material surface in a dipole first pattern.

3. The method according to claim 1, wherein: The surface includes a high-k material, and the threshold voltage shifting layer is deposited directly onto the high-k material surface in a dipole final pattern.

4. The method according to claim 1, wherein: The metal includes titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), aluminum (Al), scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La) or strontium (Sr) or a combination thereof.

5. The method according to claim 1, wherein: The oxygen-free precursor is a metal cyclopentadienyl compound, and the metal includes scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La), or strontium (Sr).

6. The method according to claim 1, wherein: The oxygen-free precursor is a metal alkylamide compound, and the metal includes titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), or aluminum (Al).

7. The method according to claim 1, wherein: The oxygen-free precursor is a metal amidine compound, and the metal includes scandium (Sc), lutetium (Lu), yttrium (Y), magnesium (Mg), lanthanum (La), or strontium (Sr).

8. The method according to claim 7, wherein: The metal amidine compound has the following formula (Formula 1): wherein: M is a metal; R and R' are independently any branched alkyl, unbranched alkyl, cyclic alkyl or non-cyclic alkyl containing 1-10 carbon atoms or a combination thereof; R" is hydrogen, dimethylamino, diethylamino, ethylmethylamino or an alkyl containing 1-6 carbon atoms.

9. The method according to claim 8, wherein: R and R' are independently selected from isopropyl, tert-butyl, sec-butyl and tert-amyl.

10. The method according to claim 8, wherein: R" is hydrogen or methyl.

11. The method according to claim 1, wherein: The sulfur-containing reactant includes H2S.

12. The method according to claim 1, wherein: The sulfur-containing reactant compound is of the formula HS(CRR')xSH, wherein R and R' are independently selected from hydrogen (H), methyl (Me), ethyl (Et), n-propyl (nPr), and x is an integer from 1 to 12.

13. The method according to claim 12, wherein: The sulfur-containing reactant is HS(CH2)2SH or HS(CH)3SH.

14. The method according to claim 1, wherein: The sulfur-containing reactant compound is of the formula S(SiRR'R")2, wherein R, R' and R" are independently selected from H, Me, Et, nPr, isopropyl (iPr), tert-butyl (tBu), n-butyl (nBu), sec-butyl (sec-Bu) and isobutyl (iso-Bu).

15. The method according to claim 14, wherein: The sulfur-containing reactant is S(SiMe3)2 or S(SiEt3)2.

16. The method according to claim 1, wherein: The sulfur-containing reactant compound is of the formula S2RR', wherein R and R' are independently selected from Me, Et, nPr, iPr, tBu, nBu, sec-Bu and iso-Bu.

17. The method according to claim 16, wherein: The sulfur-containing reactant is S2Me2, S2Et2 or S2(tBu)2.

18. The method according to claim 1, wherein: The sulfur-containing reactant compound is of the formula RSH, wherein R is a straight or branched chain alkyl group containing 1 to 10 carbon atoms.

19. The method according to claim 1, wherein: The sulfur-containing reactant comprises only sulfur atoms.

20. The method according to claim 1, wherein: The sulfur-containing reactant includes sulfur and halogen.

Images