阅读说明：本技术 用于沉积钨薄膜或钼薄膜的方法 (Method for depositing tungsten film or molybdenum film ) 是由 R·小赖特 T·H·鲍姆 B·C·亨德里克斯 S·D·阮 王瀚 P·S·H·陈 于 2019-09-24 设计创作，主要内容包括：本文描述用于沉积金属薄膜或层到衬底上的气相沉积方法,其中所述金属是钼或钨；所述方法涉及含有所述金属及一或多种含碳配体的有机金属前驱物化合物,并包含沉积由所述前驱物的所述金属形成的金属层到衬底上,随后将氧化剂引入到所述形成的金属层。(Described herein are vapor deposition methods for depositing a metal film or layer onto a substrate, wherein the metal is molybdenum or tungsten; the method involves organometallic precursor compounds containing the metal and one or more carbon-containing ligands, and includes depositing a metal layer formed from the metal of the precursor onto a substrate, followed by introducing an oxidant to the formed metal layer.)

1. A deposition method for forming a metal thin film on a substrate, the method comprising:

forming a deposited metal layer by flowing a gaseous precursor into a deposition chamber and exposing the gaseous precursor to a substrate to deposit the metal onto the substrate, the organometallic precursor comprising a metal and one or more carbon-containing ligands, wherein the metal is molybdenum or tungsten,

flowing an oxidizing agent into the deposition chamber to expose the deposited metal layer to the oxidizing agent.

2. The method of claim 1, wherein the deposited metal layer comprises carbon derived from the organometallic precursor as a contaminant, and the step of exposing the deposited metal layer to the oxidizing agent allows the oxidizing agent to react with and remove the carbon contaminant from the deposited metal layer.

3. The method of claim 1, wherein the carbon content of the metal film is reduced compared to a comparable metal film prepared by the same method but without flowing an oxidizing agent into the deposition chamber.

4. The method of claim 1, wherein the organometallic precursor is selected from: carbonyl-containing precursors, cyclopentadienyl-containing precursors, aryl precursors, alkyl-substituted aryl precursors, amide-imide-containing precursors, and amidinate or guanidinate precursors.

5. The method of claim 1, wherein the precursor is selected from molybdenum bis (ethylbenzene) and tungsten bis (ethylbenzene).

6. The method of claim 1, wherein the substrate is at a temperature of less than 400 degrees celsius during deposition of the metal onto the substrate.

7. The method of claim 1, wherein the method is a pulsed chemical vapor deposition method, the method comprising:

continuously flowing the gaseous precursor and a reducing gas co-reactant into the deposition chamber to expose the substrate to the gaseous precursor and the reducing gas co-reactant to deposit the metal onto the substrate to form a deposited metal layer comprising the metal and carbon derived from the precursor, and

flowing the oxidant into the deposition chamber by pulsed flow to expose the deposited metal layer and the carbon to the oxidant to react the oxidant with the carbon and remove the carbon from the deposited metal layer.

8. The method of claim 7, wherein the method produces a deposited metal layer having a thickness of no more than 50 angstroms.

9. The method of claim 7, comprising flowing hydrogen into the deposition chamber after exposing the deposited metal and the carbon to the oxidant.

10. The method of claim 1, wherein the method is an atomic layer deposition method, the method comprising:

flowing the gaseous precursor into the deposition chamber to expose the substrate to the metal vapor, optionally in the presence of an inert gas, depositing the metal onto the substrate to form a deposited metal layer comprising the metal and carbon derived from the precursor, and

flowing an oxidant into the deposition chamber to expose the deposited metal and the carbon to the oxidant to react the oxidant with carbon and remove the carbon from the deposited metal layer.

11. The method of claim 10, comprising flowing hydrogen into the deposition chamber to expose the deposited metal to hydrogen after exposing the deposited metal layer and the carbon to the oxidant.

12. The method of claim 10, wherein the substrate comprises a partially fabricated integrated circuit.

13. The method of claim 12, wherein the substrate comprises a dielectric layer or a nucleation layer, and the metal vapor is deposited onto the dielectric layer or the nucleation layer.

14. The method of claim 12, wherein the metal layer is deposited as a structure selected from an interconnect, a contact, and an electrode.

Technical Field

The present invention relates to a vapor deposition method for depositing a metal film, layer or other metallic structure onto a substrate, wherein the metal is molybdenum or tungsten. The method involves a metal precursor compound (or "complex") comprising a metal and one or more carbon-containing ligands, and includes depositing a metal layer formed from the metal of the precursor onto a substrate, and then introducing an oxidant into the formed metal layer under heating.

Background

Molybdenum and tungsten, particularly in purified form, are low resistivity refractory metals that are used in microelectronic devices such as memory, logic wafers, and other devices that include polysilicon-to-metal gate electrode structures. These applications have used various vapor deposition techniques and various initial material inputs to deposit thin metal layers of molybdenum or tungsten. A "precursor" compound comprising a metal is processed by a vapor deposition technique inside a deposition chamber containing a substrate, and the processing materials and conditions are sufficient to deposit the metal from the precursor as a metal layer on the substrate.

Vapor deposition techniques include Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) techniques, including many derivative versions of any of them, such as UV laser photo-dissociation CVD, plasma-assisted CVD, and plasma-ALD, among others. To deposit high purity metals on two-or three-dimensional microelectronic device substrates, CVD and ALD processes may be required because they can provide high purity, typically with good conformal step coverage over highly non-planar microelectronic device geometries. However, the cost and complexity of plasma-assisted deposition and high temperature deposition systems increases production costs and tool costs. Processes such as these that require certain higher temperatures may also damage previously deposited or underlying structures, particularly structures of logic devices known to be temperature sensitive.

In a typical CVD process, a vaporized (gaseous) precursor is contacted with an optionally heated substrate (e.g., a wafer) in a low or ambient pressure deposition chamber. Precursors introduced to the substrate decompose, leaving a metal-containing deposit on the substrate surface to form a thin layer (or "film") of highly pure deposited metal. Volatile byproducts are removed by gas flow through the deposition chamber.

In addition to gaseous precursors, vapor deposition processes may generally involve supplying one or more other gases (sometimes referred to as "reactant gases" or "co-reactants") to the deposition chamber. The reactant gases may act to cause the deposition process to occur more efficiently or with improved deposition results. Some of the reactant gases react with the precursor to release the metal of the precursor molecules for deposition as elemental metal onto the substrate. Other reactant gases may perform various functions, such as improving the performance or lifetime of the deposition chamber or deposition chamber components.

For precursors, tungsten films and molybdenum films have been formed by vapor deposition methods using some well-known fluorine-containing precursors, such as tungsten fluoride (e.g., tungsten hexafluoride, tungsten pentafluoride). However, the presence of fluorine can be detrimental to the use of fluorine-containing precursors, leading to device performance problems and the need for "special" processing measures. Non-fluorinated precursor alternatives have been developed, such as chlorine-containing precursors, for example: molybdenum pentachloride, molybdenum oxychloride (e.g. MoO)₂Cl₂And MoOCl₄) Tungsten pentachloride, tungsten hexachloride. Difficulties in using these chlorine-containing precursors in vapor deposition processes typically involve heating the substrate to a temperature of at least about 400 ℃, such as up to 800 ℃. These high temperatures require complex processing equipment and can consume the thermal budget of temperature sensitive devices, meaning that temperature sensitive substrates, such as logic devices, may be damaged. Precursors that can allow deposition of metal layers at lower temperatures would be preferred by allowing lower operating temperatures and using less expensive and less complex equipment, and temperatures for manufacturing, for example, logic devicesA sensitive device would be particularly beneficial.

Other non-fluorinated precursors include carbonyl-containing precursors (e.g., molybdenum hexacarbonyl (Mo (CO))₆) And tungsten hexacarbonyl (W (CO)₆) And imide-amide precursors. These may be deposited at temperatures lower than that required for chloride and oxychloride precursors. However, deposited metal structures suffer from high resistivity because carbon, oxygen, or nitrogen from the precursors may be incorporated into the deposited metal as contaminants. Furthermore, step coverage may lack sufficient quality for commercial applications.

Based on these considerations, there is a need to produce molybdenum and tungsten metal films and coatings on various substrates (e.g., logic devices) at lower deposition temperatures while obtaining extremely high purity deposited metal layers from various organometallic precursors.

Disclosure of Invention

In microelectronic fabrication techniques, when depositing metal layers onto thermally sensitive devices, a relatively low temperature (<400 ℃) vapor deposition process is required to deposit the layer of molybdenum or tungsten. The lower temperature deposition method allows the process to be compatible with existing logic device structures on partially fabricated device substrates. There is a particular need for a relatively low temperature process for depositing molybdenum or tungsten onto microelectronic device substrates (e.g., logic devices) to produce metal layers with purity levels that result in extremely low electrical resistance and the conformal/fill features required to fabricate these devices.

In accordance with applicants' invention, a vapor deposition process may be used to deposit a layer of highly pure molybdenum or tungsten metal onto a substrate by using a gaseous precursor comprising molybdenum or tungsten and one or more carbon-containing ligands. These vapor deposition processes may be performed at relatively low temperatures, meaning temperatures lower than the deposition temperatures required for vapor deposition processes using halogenated (e.g., fluorinated, chlorinated, brominated, iodinated) or oxyhalogenated precursors, for example. The vapor deposition method of the present invention includes flowing a gaseous organometallic precursor into a deposition chamber containing a substrate for deposition and optionally a co-reactant. The conditions of the deposition chamber (e.g., elevated temperature) and the flow and pressure combinations of the precursors and optional co-reactants cause the tungsten or molybdenum metal from the precursors to be deposited as a substantially pure deposited metal film onto the surface of the substrate.

The vapor deposition step may be carried out by an atomic layer deposition process, by a chemical vapor deposition process, or by a modified or derivative form of these processes, in any suitable manner as variously described herein. The method is performed using process parameters and conditions including a pulsed flow of an oxidizing agent, for example, that reacts with carbon in the deposition system at the surface of the deposited metal layer to oxidize the carbon and remove the carbon from the deposited metal layer or prevent the carbon from being deposited on the metal layer. The resulting metal layer is highly pure, including a low concentration of carbon, preferably a concentration of carbon that is lower than the concentration of carbon contained in a metal layer prepared by a similar vapor deposition process that does not include providing an oxidizing agent to the deposition chamber as described herein.

The molybdenum or tungsten layer may be deposited onto any desired substrate and any particular material of the substrate, with example substrates being microelectronic device substrates "in-process" (meaning in a process in which fabrication is not yet complete). The microelectronic device may be a memory function provider or a logic function provider. Examples of functions of deposited molybdenum or tungsten include: as a conductive layer of a microelectronic logic device (e.g., as an interconnect, contact, or electrode). The deposited molybdenum may have a thickness effective to perform the desired function and may be continuous. The method is particularly suitable for depositing a metal layer onto a substrate comprising logic functions, which substrate is known to be temperature sensitive. The vapor deposition process as described herein can be carried out at relatively low temperatures without damaging these temperature sensitive substrates.

One aspect of the present invention is a vapor deposition method for forming a metal thin film on a substrate. The method comprises the following steps: a deposited metal layer is formed by flowing a gaseous precursor into a deposition chamber and exposing the gaseous precursor to a substrate to deposit a metal onto the substrate. The precursor includes a metal and one or more carbon-containing ligands, wherein the metal is molybdenum or tungsten. The method also includes flowing an oxidizing agent into the deposition chamber to expose the deposited metal layer to the oxidizing agent.

Drawings

FIG. 1 illustrates one example of a system that can be used for the described vapor deposition method.

Fig. 2 illustrates one example of an input stream for the described vapor deposition process using a pulsed oxidant stream.

Detailed Description

The following description relates to vapor deposition methods that utilize relatively low temperatures for depositing layers of highly pure molybdenum or tungsten metal onto substrates by using gaseous precursors that include molybdenum or tungsten and one or more carbon-containing ligands. The vapor deposition method includes flowing a gaseous metal-containing precursor to the interior of a deposition chamber containing a substrate for deposition and optionally a co-reactant. The conditions of the deposition chamber (e.g., high temperature) and the flow and pressure combinations of the precursors and optional co-reactants cause the deposition of a thin film of the deposited metal from the precursors in substantially pure tungsten or molybdenum metal onto the surface of the substrate.

With respect to challenges with vapor deposition methods using these types of precursors, the conditions of the deposition chamber may also allow or cause small amounts of carbon derived from the precursor ligands to deposit as contaminants in the metal layer. When the precursor includes a carbon-containing ligand, such as a carbonyl, alkylamido, alkylamino, alkyl or aryl group (which may be substituted) or cyclopentadienyl group, carbon from the ligand may be released in the deposition chamber during the deposition process. At temperatures commonly used for vapor deposition processes using these types of precursors, which may be lower than the temperatures used to deposit metal layers on substrates from various other types of precursors, such as halogenated precursors (i.e., fluorinated or chlorinated precursors), the precursor carbon may be used with the metal as part of the deposited metal film, such as in the form of a metal carbide (e.g., molybdenum carbide (Mo) carbide)₂C) Or tungsten carbide (WC)) is deposited. Any such carbon contained in the metal layer is an undesirable contaminant because it can adversely affect the performance of the metal film in the microelectronic device. Carbon can, for example, undesirably increase the resistivity of the film, alter the morphology or identity of the film, or both.

In accordance with the present invention, applicants have determined that an oxidizing agent (e.g., gaseous oxygen (O)₂) Ozone (O)₃) Or water (H)₂O) and hydrogen (H)₂) Combinations of (b) may be introduced into the deposition chamber in this type of deposition process, for example, to improve the composition of the deposited metal layer. The oxidizing agent is introduced in an amount and manner such that the oxidizing agent reduces the amount of carbon deposited in the finished metal layer; for example, the oxidizing agent may react with and remove carbon from the surface of the metal layer during the deposition process.

The presently described methods of depositing a metal layer onto a substrate using organometallic precursors may be any type of vapor deposition method, including those methods commonly referred to as atomic layer deposition, those methods commonly referred to as chemical vapor deposition, or a modification of any of these methods.

Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) are chemical processes by which chemical precursors, optionally and typically in combination with one or more other materials (e.g., co-reactants), can be introduced to a substrate within a deposition chamber, and the result is the formation of a thin "layer" or "film" of the material derived from the precursor on the surface of the substrate. In a chemical vapor deposition step, the thickness of the deposited material may be controlled by deposition parameters, such as the length of time the substrate is exposed to the precursor. In an atomic layer deposition step, the thickness of the deposited layer may be "self-limiting" based on process conditions (e.g., the deposition temperature and pressure selected).

According to the present invention, a gaseous organometallic precursor comprising molybdenum or tungsten as the metal and one or more optional co-reactant gases are introduced into a deposition chamber (also referred to as a "reaction chamber") comprising a substrate. A gaseous metal precursor is a chemical compound that includes a metal atom chemically associated with one or more carbon-containing chemical groups (i.e., "ligands") attached to the metal atom. The pressure and flow rate of the precursor and optional co-reactant gas streams, and the deposition chamber conditions (e.g., temperature, pressure, temperature of the substrate, and other conditions) are selected such that metal atoms of the precursor are released from ligands of the precursor within the deposition chamber and metal is deposited onto the surface of the substrate. Volatile byproducts of the deposition process may be removed by gas flow through the deposition chamber.

If needed or desired, the gaseous organometallic precursor may be carried to the deposition chamber using a carrier gas, which may be an inert gas such as helium, argon, nitrogen, or combinations thereof. A carrier gas may be mixed with the gaseous organometallic precursor such that the carrier gas carries the desired concentration and desired total amount of the gaseous precursor to the reaction chamber containing the substrate. The concentration of the gaseous precursor in the carrier gas and the flow rate of the gaseous carrier gas-precursor mixture to the deposition chamber may be selected as desired and effective to produce the desired deposited metal layer in a particular deposition process, with the particular values of these parameters being selected, among other parameters, in combination with other parameters of the deposition process, such as the size (volume) of the deposition chamber, the flow rate of the co-reactant gas, the substrate temperature, the deposition chamber pressure, and the like.

In addition, if necessary or desired, a co-reactant (e.g., a reducing gas (referred to herein as a "co-reactant gas"), such as hydrogen (H), is typically introduced₂) Is introduced into the deposition chamber to facilitate deposition of elemental metal from the precursor onto the substrate surface. The relative amounts (e.g., relative flow rates, pressures, etc.) of the co-reactant gases introduced to the deposition chamber may be selected as desired and effective in a particular process to produce a desired deposited metal layer, with the particular values of these parameters being selected in combination with other parameters of the deposition process, such as the flow rates of the precursors, the substrate temperature, and the chamber pressure. Furthermore, various other steps may be performed and parameters controlled, such as heating the substrate, selectively purging the deposition chamber by introducing a gaseous atmosphere or by vacuum steps, among other optional or desired steps, according to the described vapor deposition method.

The precursors used in the vapor deposition step are organometallic precursors comprising tungsten or molybdenum and one or more organic ligands chemically bound to the metal center. The organic ligand comprises carbon and may contain hydrogen and oxygen, and may be in the form of a chain of carbon atoms or one of the carbon atoms to which an oxygen or hydrogen atom is bonded, and one or more functional groups (e.g., amino, carbonyl, etc.) bonded to the carbon.The ligand may be or include, for example, an alkyl group, a substituted alkyl group, an optionally substituted cyclic or aromatic group, a carbonyl (-c (o)), an alkylamido group, an alkylimido group, or a combination of these. Examples of these types of gaseous metal precursors (sometimes referred to as "organometallic" precursors) are known in the vapor deposition art and include compounds referred to as organometallic carbonyl precursors, and organometallic amide-imide precursors. Specific examples include molybdenum bis (ethylbenzene), tungsten bis (ethylbenzene), molybdenum hexacarbonyl (Mo (CO)₆) Tungsten hexacarbonyl (W (CO))₆) And cyclopentadienyl (Cp) complexes of molybdenum and tungsten, and alkylcyclopentadienyl and hydride complexes of molybdenum and tungsten.

One feature of the vapor deposition process of the present invention is that the deposition temperature is relatively lower than the deposition temperature required to deposit a metal layer from some other type of precursor. The deposition temperature of the vapor deposition process using organometallic precursors that include carbon-containing ligands is relatively low compared to the temperature required for deposition using halogenated (fluorinated, chlorinated, brominated, iodinated) or oxyhalogenated precursors. The vapor deposition of the metal layer using various organometallic precursors may be accomplished at temperatures below about 400 degrees celsius, such as below about 300 degrees celsius. Advantageously, these lower temperatures allow the presently described methods to be used with heat sensitive substrates, such as microelectronic devices (e.g., microprocessors) designed to perform logic functions. Yet another feature of these relatively low temperature vapor deposition steps using organometallic precursors may be the presence of carbon contaminants in the deposited layer of metal.

To remove carbon, an oxidizing agent is introduced into the deposition chamber in a manner such that the oxidizing agent reacts with carbon present in the deposited metal film. The oxidizing agent inhibits or prevents carbon deposition onto the metal layer during deposition by reacting with the carbon, or removes the carbon from the deposited metal layer. The oxidizing agent can be any gaseous chemical material that will react with carbon present in the deposited film (e.g., present in the metal layer) to form volatile compounds that separate from the metal layer and inhibit or prevent the incorporation of carbon into the metal layer.

Examples of useful oxidizing agentsComprising gaseous oxygen (O)₂) Ozone (O)₃) And a combination of water vapor and gaseous hydrogen. The oxidizing agent (e.g., gaseous oxygen) can react with carbon present in the deposited film (e.g., as a contaminant in the metal layer) and produce carbon dioxide that is not incorporated into the metal layer or separated from the metal during the deposition step. The oxidizing agent may be introduced into the deposition chamber in an amount, manner, flow rate, time, and pressure effective to cause the oxidizing agent to react with the carbon during deposition of the metal layer. In a preferred method, the metal film prepared by using oxygen during deposition may comprise a reduced amount of carbon compared to the amount of carbon present in a comparable metal film prepared by the same method and from the same material (but not including introducing an oxidizing agent into the deposition chamber). In a preferred method, the resistivity of a metal film prepared by using oxygen during deposition may be lower than the resistivity of a comparable metal film prepared by the same method and from the same materials (but not including introducing an oxidizing agent into the deposition chamber and process). In certain presently preferred example methods, the oxidizing agent is effective to remove carbon from the deposited metal layer, or to prevent the incorporation of carbon into the metal layer, when the oxidizing agent is introduced into the deposition process in an "interrupted" or "pulsed" manner, meaning that the flow rate of the gaseous oxidizing agent is not stable and the time of the pulsed introduction can be controlled.

Depositing elemental molybdenum or tungsten as described using gaseous organometallic precursors including molybdenum or tungsten and one or more carbon-containing ligands may be performed using available vapor deposition equipment and generally known techniques suitable for depositing layers of elemental molybdenum or tungsten from the precursors, with additional introduction of oxygen into the deposition chamber to remove carbon from the deposited metal layer.

As one example of a useful system for the methods of the invention, fig. 1 shows schematically (not to scale) a system that can be used to carry out the vapor deposition process described, which can be chemical vapor deposition, atomic layer deposition, or a modified version or derivative of any of these methods. FIG. 1 shows a vapor deposition system 2 that includes a deposition chamber 10 having an interior 12, the interior 12 containing a platen 14, the platen 14 supporting a substrate 16. As shown, the interior 12 is sized to accommodate only a single substrate 16, but may alternatively have any size necessary to accommodate multiple substrates for vapor deposition processing.

Still referring to FIG. 1, cylinders 40, 42, 44, and 46 are connected to interior 12 to allow the selective flow of gaseous fluid from each cylinder into interior 12. Each of the cylinders may include a liquid or gaseous starting substance that is supplied to the interior 12 in gaseous form for the vapor deposition step. For example, cylinder 46 may contain liquid, solid, or gaseous organometallic precursors. Cylinder 44 may contain an inert gas that acts as a carrier gas to carry a concentration of organometallic precursor to interior 12. In use, carrier gas from the gas cylinder 44 containing the carrier gas may flow through a conduit, which may also be connected to the gas cylinder 46 containing the precursor through an open valve. A combination of carrier gas and precursor may be controlled to flow into the chamber 12.

Cylinder 42 is optional and may contain a co-reactant (e.g., hydrogen), another reducing gas, or a different co-reactant. One or more additional optional cylinders (not shown) may also be present to receive and supply any of a variety of other useful or co-reactants or other gaseous fluids, such as another inert gas (e.g., for a purging step), to the interior 12.

The cylinder 40 contains an oxidant, such as oxygen (O)₂)。

Although not explicitly shown, any of a variety of known measurement or flow control devices may also be present in system 2 to monitor and adjust the flow and relative flow of each gaseous fluid from the cylinders, as well as conditions, such as the temperature or pressure of the gaseous stream, the temperature of interior 12, or the temperature of platen 14 or substrate 16; these may include pressure regulators, flow regulators (e.g., mass flow regulators), sensors (pressure sensors, temperature sensors), and the like. The control system 50, which may be or include a computer, Central Processing Unit (CPU), Programmable Logic Controller (PLC), or the like, including wiring 52 or other (e.g., wireless) communication means to electrically connect the control system 50 to selected valves, sensors, or other flow control devices of the vapor deposition system 2, by controlling the valves and optionally other flow control mechanisms, and by monitoring the pressure and temperature sensors, the control system 50 can effectively control the flow of each fluid of the cylinders to provide a desired combination of gaseous fluid flows from the cylinders into the chamber 12.

In an alternative system such as the system of fig. 1, or described as also being effective for vapor deposition of molybdenum or tungsten, deposition process parameters can be controlled to perform vapor deposition as presently described, including: depositing a substantially pure metal layer onto a surface of a substrate having a metal layer containing carbon contaminants; and dispensing an oxidant into the interior to oxidize carbon contaminants and remove carbon from the deposition chamber or from the metal layer (if already deposited). With carbon removed, the deposited metal layer will have higher purity and improved properties, such as improved (reduced) resistivity, of the deposited metal layer of the microelectronic device relative to a comparable deposited metal layer prepared by a similar deposition process (using the same materials and methods) that has not had carbon removed by exposure to and reaction with an oxidizing agent as described herein.

The method of depositing elemental tungsten or molybdenum on a substrate surface as a substantially pure metal layer may be carried out by a deposition step or a series of deposition steps that can provide a substantially pure metal layer having a desired level of purity, particularly with respect to relatively low levels of carbon contamination. Various options are available for how the gaseous organometallic precursor is supplied to the interior of the deposition chamber, and how the metal of the precursor is deposited onto the substrate. The variables (parameters) of the vapor deposition process include: the pressure and flow rate of the gaseous organometallic precursor; the relative amount of gaseous precursor to inert carrier gas (if used); the presence and type of any co-reactant (e.g. reducing gas); the relative amount of precursor gas to co-reactant; purging with an inert gas in the process; and whether the flow of the gaseous precursor, co-reactant, oxidant, or inert purge gas is continuous (i.e., steady or uniform) or pulsed (e.g., interrupted).

The flow of gaseous materials (e.g., organometallic precursors (e.g., as part of a carrier gas-precursor mixture), co-reactants, oxidants, etc.) may be continuous (i.e., steady or uniform) or pulsed (e.g., "interrupted" or "non-uniform") as desired and for various reasons. If pulsed, the flow of gaseous fluid is not continuous but is caused to intermittently (e.g., periodically) flow into the deposition chamber and then not flow into the deposition chamber, with the cycle including an in-flow period and an out-flow period during the deposition process. Other gaseous materials (e.g., precursors, co-reactants, inert purge gases, etc.) may be supplied to the deposition chamber in a continuous or pulsed manner during the same deposition process. A purge period or a vacuum period may be used in the process as desired. One reason for using a pulsed process is to improve the conformality or step coverage of the deposited thin film on the non-planar structure.

In certain embodiments of the method, the flow of gaseous organometallic precursor (e.g., as part of a carrier gas-precursor mixture) may be stable, the flow of one or more co-reactant may be stable, and the flow of oxidant may be pulsed (i.e., interrupted), with an in-flow period of oxidant and an out-flow period of oxidant comprising one pulsed "cycle" of oxidant. See fig. 2. The oxidant flow is discontinuous, but is intermittently (e.g., periodically) pulsed onto the deposition chamber (during the "in-flow" period), and then pulsed off the deposition chamber in a cyclic manner throughout the film deposition step (during the "out-flow" period).

According to other example methods (sometimes referred to as "continuous" vapor deposition methods), a plurality of different gaseous fluids (e.g., precursors, oxidants, co-reactants, and inert purge gases) may be supplied to a deposition chamber in alternating and continuous pulses in a deposition method, such as: opening the precursor stream for a first period of time while closing the flow of co-reactant gas and oxidant; subsequently opening the co-reactant flow for a second period while closing the precursor and oxidant flows; subsequently closing the precursor and co-reactant flows for a third period of time while opening the oxidant flow; the precursor, oxidant or co-reactant flows are all discontinuous and each flow is interrupted or "pulsed". In another example: opening both the precursor stream and the co-reactant during a first period while closing the oxidant stream; subsequently opening the oxidant stream for a period of time; followed by another period, such as a first period, in which both the precursor stream and the co-reactant are turned on while the oxidant stream is turned off; an inert purge gas may be flowed through the deposition chamber after the first precursor and co-reactant flows but before the oxidant flow, and then again after the oxidant flow but before the continuous precursor and co-reactant flows.

Each inflow period and each outflow period of any pulsed flow of a gaseous fluid may be the same or different relative to the inflow period and the outflow period of another gaseous fluid. And the inflow period of a particular gaseous fluid may be the same or different than the outflow period. One or more purge or vacuum periods may be included in the method as desired, for example, between any inflow or outflow periods.

According to certain examples of the methods of the present invention, a metal layer is deposited onto a substrate and carbon is removed from or inhibited from being deposited onto the metal layer by a deposition step comprising a continuous flow of a gaseous organometallic precursor, a continuous flow of a co-reactant, and a pulsed (non-continuous) flow of an oxidant. Referring to fig. 2 and example 1, a CVD process is shown. A combination of continuous flow of organometallic precursor and reducing gas and pulsed oxidant flow may be used to deposit a desired amount of a metal layer (e.g., based on thickness) onto a substrate, with the oxidant being introduced intermittently during deposition of the metal layer. The deposition process includes periods of continuous precursor and co-reactant flow concurrent with multiple pulsed cycles of an oxidant, each cycle of the oxidant including an in-flow period and an out-flow period. The total number of pulse cycles, and the length of each cycle and its in-flow and out-flow periods, may be selected to achieve a desired effect of removing carbon from or preventing carbon deposition in the metal layer, providing a deposited metal layer comprising a reduced amount of carbon contaminants compared to a comparable method that does not include the presence of an oxidizing agent (e.g., the method of fig. 2, in the absence of an oxidizing agent).

According to other embodiments of the method of the present invention, the metal layer is formed by pulsing a flow of a reducing gas, a pulse of an oxidizing agent, and an organometallic precursorA deposition method of pulsing of the purge gas and the flushing is deposited onto the substrate. Referring to example 2, an ALD process is shown. The first inflow provides the precursor supplied with the inert carrier gas, while no other flows enter the deposition chamber (i.e., "single"). The inflow immediately thereafter is an inert purge gas, with no other flows. The next subsequent inflow is with H₂A combined stream oxidant; the oxidizing agent is effective for removing carbon and reducing H from the surface of the grown deposited metal layer film₂The gas may reduce other contaminants present on the surface, such as oxygen. The oxidant and reducing gases are followed by a second pulsed flow of inert purge gas. After the second inflow of purge gas, the series is repeated starting with a precursor flow in carrier gas. By said method, these flows are not continuous and all said flows are pulsed. The overall deposition process includes a metal layer deposition period followed by a purge, followed by an oxidant flow period to remove carbon and reducing gas flow reducing contaminants from the surface of the deposited metal layer, followed by a second purge, after which the series is repeated. The total number of iterations of the series produces a metal layer having a desired thickness and comprising a reduced amount of carbon as compared to a metal layer produced by a comparable process that does not include an oxidant stream.

Yet another example of a vapor deposition method includes a series of pulsed flows including a pulsed flow of organometallic precursor (alone), a pulsed flow of inert purge gas, a pulsed flow of oxidant (e.g., water and hydrogen), an optional pulsed flow of gaseous hydrogen, and a second pulsed flow of inert purge gas. Referring to example 3, an ALD process is shown. The first inflow separately provides the precursor, optionally supplied with an inert carrier gas (no other flow enters the deposition chamber during the inflow). The inflow immediately thereafter is an inert purge gas, with no other flows (i.e., alone). The next subsequent inflow is oxidant (e.g., water vapor and gaseous hydrogen), with no other flows; the oxidizing agent is effective to remove carbon from the surface of the deposited metal layer. After the oxidizing step, a pulse of reducing gas may optionally be flowed into the deposition chamber without additional flow; the reducing gas may reduce other contaminants present on the surface, such as oxygen. The oxidant inflow or the optional reducing gas inflow is followed by a second pulsed flow of inert purge gas. After the second inflow of purge gas, the series is repeated starting from the precursor flow. By the method, these streams are not continuous, and each identified gaseous composition (comprising water and oxygen in combination or otherwise) may be flowed separately to the deposition chamber. The overall deposition method includes a metal layer deposition process followed by a purge followed by an oxidant flow period to remove carbon from the surface of the deposited metal layer, optionally followed by a reducing gas to reduce other contaminants (e.g., oxygen), followed by a second purge, after which the series is repeated. The total number of iterations of the series produces a metal layer having a desired thickness and comprising a reduced amount of carbon as compared to a metal layer produced by a comparable process that does not include an oxidant stream.

The method may be performed in a deposition chamber that during use includes substantially only gaseous precursors, optional carrier gases, co-reactant gases, optional inert purge gases, and oxidizing agents as atmospheres, for example, a deposition chamber atmosphere may include, consist of, or consist essentially of a combination of: a gaseous precursor, an optional carrier gas, an optional purge gas, a co-reactant gas, and an oxidizing agent. For purposes of the present invention, a deposition chamber or associated gas stream or combination of gas streams consisting essentially of a specified combination of gaseous materials is considered to comprise the specified combination of gaseous materials and no more than a non-bulk amount of any other gaseous material (e.g., no more than 2, 1, 0.5, 0.1, 0.05, 0.01, or 0.005% (by mass) of any other gaseous material).

The amount of gaseous precursor (also referred to as precursor vapor), the amount of co-reactant gas, the amount of optional purge gas, and the amount of oxidant supplied to the deposition chamber may be amounts useful to produce the desired effect of each gaseous fluid to produce each of the metal layers of molybdenum or tungsten and the desired small amount of carbon as a result of the process. The respective amounts of gases supplied to the deposition chamber, in terms of their respective flow rates, may be based on factors including other process parameters, the desired amount (e.g., thickness) of metal layer being deposited, the desired deposition rate, the size (volume) of the deposition chamber, and the internal pressure of the deposition chamber. Further, the example amounts and ranges described as being available for each gaseous fluid supplied to the deposition chamber may be consistent with respect to each other, but larger or smaller based on similar mathematical factors determined by the dimensions of the deposition chamber used.

According to non-limiting examples of certain methods that have been identified as useful, the precursor-carrier gas mixture may include a precursor (contained in an inert gas (e.g., Ar, H) in the range of 0.01 to 5 percent₂Or a combination of these) and can flow to the deposition chamber at a rate useful for coating 300mm wafers, which is desirable for large scale semiconductor manufacturing. Example flow rates of precursor-carrier gas mixtures for supporting chambers operating 300mm wafers at internal pressures ranging from 0.1 to 500 torr may be in the range of 25 to 5,000 standard cubic centimeters per minute (25-5,000 sccm). Example flow rates can range from 10 to 400sccm per cubic inch of the deposition chamber volume, such as from 1 to 100sccm per cubic inch of the deposition chamber volume, based on the flow rate per chamber volume. Example flows may be in the range of 0.1 to 100 micromoles per minute, e.g., 1 to 50 or 2 to 20 micromoles per minute, based on the amount of precursor flowing to the deposition chamber.

According to non-limiting examples of certain methods that have been determined to be useful, the flow rate of the co-reactant gas (e.g., hydrogen), which may be continuous during the pulse cycle, may be in the range of 10 or 20 to 1000sccm, which is useful for deposition chambers that support a single 300mm wafer and operate at internal pressures in the range of 0.1 to 500 torr; a larger chamber will require a correspondingly larger flow rate.

The internal pressure of the deposition chamber may be an internal pressure effective to deposit the metal layer. Typically, deposition chambers used for chemical vapor deposition are operated at a pressure no greater than approximately ambient pressure (commonly understood to be about 760 torr). Typically, the deposition chamber will operate at a pressure substantially below atmospheric pressure, such as an internal pressure in the range of 0.1 to 300, 400, or 500 torr, such as in the range of 1, 5, or 10 torr to 100 torr.

During deposition, the substrate may be maintained at any temperature effective to deposit molybdenum or tungsten onto the substrate according to the present invention. The use of organometallic precursors for tungsten or molybdenum should be understood to allow for lower substrate temperatures during deposition than are required to deposit tungsten or molybdenum onto a substrate using other halogenated precursors (e.g., fluorinated, chlorinated, brominated, iodinated) and oxyhalogenated precursors. For the method of the present invention, the substrate may be maintained at an elevated temperature of no more than 400 ℃ during the deposition step, for example, the temperature may be in the range of 100 ℃ to 350 ℃, or in the range of 150 ℃ to 300 ℃.

The method may be performed by a deposition step that includes process parameters, including those described herein (alone or in combination), that will result in one or a desired combination of various desired physical properties of the processed substrate. The desired physical properties include a desired degree of uniformity of a metal layer on a horizontal or non-planar surface of a substrate or to create interconnects, contacts, electrodes, or the like; a degree of desired conformality of a metal layer on a three-dimensionally processed substrate; the desired composition of the deposited metal layer, such as low impurity (e.g., carbon or other non-metallic material) content; the resistivity of the deposited metal layer is low; or one or more of a combination of these properties.

The vapor deposition step may be carried out in any suitable manner as variously described herein, preferably using process parameters including a combination of pulsed flow of the oxidant and values of other process parameters (including optional pulsed flow of other gaseous fluids) that will result in a deposited layer of molybdenum or tungsten that exhibits desirable physical properties, such as high purity and low resistivity. Molybdenum or tungsten may be deposited onto any desired substrate surface, such as the surface of a semiconductor or microelectronic device substrate, and may be suitable as part of a device for performing any useful function or facilitating processing of the device. Examples of functions of deposited molybdenum or tungsten include: as a conductive layer (e.g., as a via, channel, or contact) of a microelectronic logic or memory device. The deposited molybdenum may have a thickness effective to perform the desired function and may be continuous.

The substrate and surface on which the molybdenum or tungsten is deposited may comprise any two-dimensional or three-dimensional structure, a specific example of a microelectronic device substrate being a memory device (such as a DRAM device or a 3D NAND device) or a "logic" device. The logic device may be a microelectronic device including a microprocessor. Examples include Programmable Logic Devices (PLDs) having configurable logic and flip-flops coupled together with programmable interconnects. The or another logic device may provide microprocessor or other electronic functions such as device-to-device interfacing, data communication, signal processing, data display, timing and control operations, and the like. Other specific examples include those referred to as: a Programmable Logic Array (PLA); programmable Array Logic (PAL) (e.g., logic devices having fixed OR arrays AND programmable AND arrays), AND continuous programmable logic devices (including flip-flops AND AND-OR arrays within IC chips).

The particular chemical composition of the surface of the memory or logic type substrate on which the metal layer is to be deposited may be any chemical composition that can be used in the device to provide a deposited layer of molybdenum or tungsten. In general, the metal layer may be deposited on the dielectric layer or the nucleation layer. Non-limiting examples of materials that can deposit the substrate surface of molybdenum or tungsten include: silicon, silicon dioxide, silicon nitride, other silicon-based materials, titanium nitride (TiN), molybdenum (metal), molybdenum carbide (MoC), boron (B), tungsten (W), and tungsten carbon nitride (WCN).

Advantageously, the relatively lower deposition temperatures used to deposit tungsten or molybdenum may allow the deposition temperatures to not degrade the temperature sensitive features of the logic device and also provide a metal layer with a reduced content of carbon contaminants relative to other precursors or methods, while using a combination of organometallic precursors (e.g., carbonyl-type precursors or amide-imide precursors, aryl or substituted aryl precursors) and an oxidizing agent to remove carbon from the deposited thin film or metal layer.

An example vapor deposition series according to the present invention includes the following:

example 1 (pulse CVD)

At low temperatures and lead to Mo₂C other conditions of deposition, but with good step coverage, continuous CVD with pulsed oxygen was used. See alsoFig. 2 and tables 1 to 4.

The series is as follows:

(EtBz)₂Mo+H₂ /(EtBz)₂Mo+O₂:H₂<50％

example 2(ALD)

The series is as follows:

(EtBz)2Mo + Inactive/Inactive purge/(O)₂/H₂) Inert purification

The temperature and pressure are controlled to result in self-limiting deposition with respect to precursor dose time.

Oxygen (O)₂) The dose is limited by surface oxidation of Mo.

Hydrogen (H)₂) The dose is sufficient to remove substantially all of the oxygen from the surface.

Example 3(ALD)

The series is as follows:

mo imide amide/inert purge/(H)₂O+H₂) Optionally H₂Inert purification

The temperature and pressure are controlled to result in self-limiting deposition with respect to precursor dose time.

Results of example 1

Tables 1-4 contain data for an evaluation of various processing conditions and parameters of the method of the present invention using a pulsed CVD process generally as described in example 1. In the table, the thickness of the deposited film (e.g., XRF Mo) or the carbon content of the deposited film (XRF C) was measured by x-ray fluorescence (XRF).

Tables 1-4 show that using a pulsed flow of an oxidizing agent during the formation of a metal layer, which can result in a reduction in the concentration of carbon in the metal layer, a method performed according to example 1 and the general procedure of fig. 2.

O₂Influence on the carbon content

200 ℃, 30 torr, 10. mu. mol/min, 400sccm H₂，3.5sccm O₂

O₂The addition of (2) reduces the carbon content of the MoC film

TABLE 1

O₂Influence of pulses on carbon content

200 ℃, 20 torr, 10. mu. mol/min, 400sccm H₂，3.5sccm O₂Pulse of light

O₂By addition of (2) reducing the carbon content

TABLE 2

O₂Effect of Co-reactants on Mo deposition

200 ℃, 15 torr, 10. mu. mol/min, 400sccm H₂，3.5sccm O₂Pulse of light

O₂By addition of (2) reducing the carbon content

TABLE 3

O₂Effect of Co-reactants on Mo deposition

175 deg.C, 30 Torr, 10. mu. mol/min, 400sccm H₂，3.5sccm O₂Pulse of light

O₂The addition of (2) reduces the carbon content of the deposited MoC film

TABLE 4