Molybdenum liners for tungsten metallization

Abstract

A method including providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a liner layer disposed between the conductive fill material and the dielectric layer to line the feature; and replacing at least some of the liner layer with molybdenum while leaving the conductive fill material substantially intact.

Description

Atorney Docket No. LAM1P096WO-12193-1WO MOLYBDENUM LINERS FOR TUNGSTEN METALLIZATION INCORPORATION BY REFERENCE

[0001] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority7to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.BACKGROUND

[0002] Various structures in semiconductor devices employ stacks including tungsten (W) on a titanium nitride (TiN) layer. Examples include interconnects in back-end-of-line (BEOL) fabrication. The TiN layer is typically a thin liner layer with tungsten forming the bulk conductive material of the structure.

[0003] The background description provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] One aspect of the disclosure relates to a method including providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a liner layer disposed between the conductive fill material and the dielectric layer to line the feature; and replacing at least some of the liner layer with molybdenum while leaving the conductive fill material substantially intact.

[0005] In some embodiments, replacing at least some of the liner layer with molybdenum includes exposing the liner layer to a molybdenum-containing etchant to selectively etch the liner layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material. In some such embodiments, wherein replacing at least some of the liner layer with molybdenum includes exposing the substrate to a molybdenum-containing precursor to deposit molybdenum in the void. In some such embodiments, the molybdenum-containing etchant and the molybdenum-containing precursor are same molybdenum-containing compound or are generated from the same molybdenum-containing compound.

[0006] In some embodiments, the molybdenum-containing etchant is molybdenum pentachloride (MoCh).

[0007] In some embodiments, at least some of the selectively etching and depositing operations overlap.

[0008] In some embodiments, the conductive fill material is tungsten and the liner layer isAtorney Docket No. LAM1P096WO-12193-1WO titanium nitride.

[0009] In some embodiments, replacing at least some of the liner layer with molybdenum includes exposing the liner layer to a MoCh to selectively etch the liner layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material.

[0010] In some embodiments, replacing at least some of the liner layer with molybdenum includes exposing the liner layer to an etchant to selectively etch the liner layer wi th respect to the conductive fill material.

[0011] In some such embodiments, the etchant is one of or is a plasma generated from one of: chlorine (Cb), chlorine dioxide (CIO2), boron trichloride (BCh), carbon tetrachloride (CCU), thionyl chloride (SOCh), sulfur hexafluoride (SFs), trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum hexafluoride (MoFe), or molybdenum oxytetrachloride (MoOCU).

[0012] Another aspect of the disclosure relates to a method including: providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a titanium nitride liner layer disposed between the conductive fill material and the dielectric layer to line the feature; and exposing the substrate to molybdenum pentachloride (M0CI5) to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact.

[0013] In some embodiments, exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact includes a first phase in which the substrate is exposed to multiple cycles of alternating molybdenum pentachloride and purge gas without exposure to hydrogen during or between the multiple cycles. In some embodiments, exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact includes a second phase in which the substrate is exposed to molybdenum pentachloride and hydrogen.BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 shows an example of a stack of layers including a barrier layer.

[0015] Figure 2 shows an example of multiple filled features formed in dielectric layer.

[0016] Figure 3 shows operations in a method of replacing the TiN liner with Mo.

[0017] Figures 4A-4C shows examples of features at various stages of a process according to Figure 3.

[0018] Figure 5 shows an example schematic illustration of a side view of a back-end-of-line (BEOL) structure including a conductive tungsten fill layer and a molybdenum liner.Atorney Docket No. LAM1P096WO-12193-1WO

[0019] Figures 6-8 show timing schematic illustrations for example deposition processes.

[0020] Figure 9 shows a timing schematic illustrations for example etch processes.

[0021] Figure 10 depicts a pressure time graph of a pulse operation using a single charge volume.

[0022] Figure 11 depicts a pressure time graph of a pulse operation using multiple charge volumes.

[0023] Figure 12A illustrates a deposition apparatus suitable for depositing molybdenum-containing films using provided methods.

[0024] Figure 12B illustrates a station including multiple charge volumes.

[0025] Figures 13A and 13B show examples of processing systems.DETAILED DESCRIPTION

[0026] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0027] Semiconductor fabrication processes involve formation of metal-containing features having particular a particular structure. Metal fill, such as tungsten (W) fill, of features is often used in semiconductor device fabrication to form electrical contacts. There are various challenges in tungsten fill as devices scale to smaller technology nodes and more complex patterning structures are used. One challenge is reducing the fluorine concentration or content in the deposited tungsten film. A certain fluorine concentration in a tungsten film affects device performance more substantially as tungsten feature size decreases. For example, the smaller the feature, the thinner the films that are deposited within the feature. As a result, fluorine in the deposited tungsten film is more likely to diffuse through the thinner films, thereby potentially causing device failure.

[0028] One method of preventing fluorine diffusion includes depositing one or more barrier layers prior to depositing tungsten. The barrier layers prevent fluorine from diffusing from tungsten to other layers of the substrate such as an oxide or other dielectric layer.

[0029] Figure 1 shows an example of a stack of layers including a barrier layer. The layers include a dielectric layer 104, a titanium nitride layer 106, and tungsten layer 108. Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped layers of silicon nitride (SiN), silicon dioxide (SiCh), and aluminum oxide (AI2O3). Underlying the dielectric layer is a stack 102 including a semiconductor wafer having one or more layers of material, such as dielectric,Atorney Docket No. LAM1P096WO-12193-1WO conducting, or semi-conducting material deposited thereon. The semiconductor wafer may a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, for example, and may be or include silicon (Si) or silicon germanium (SiGe). The methods may also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like. The titanium nitride layer 106 is disposed between the dielectric layer 104 and tungsten layer 108. As described above, the titanium nitride layer 106 can prevent the diffusion of fluorine during formation of the tungsten layer 108.

[0030] Another challenge is reducing resistance in the deposited tungsten films. Thinner films tend to have higher resistance than thicker films. As features become smaller, the tungsten contact or line resistance increases due to scattering effects in the thinner tungsten films. Low resistivity tungsten films minimize power losses and overheating in integrated circuit designs. Tungsten nucleation layers can be deposited to facilitate tungsten bulk growth but typically have higher electrical resistivities than the overlying bulk layers. Barrier layers deposited in contacts, vias, and other features, may also have high resistivities. Further, thin barrier and tungsten nucleation films occupy a larger percentage of smaller features, increasing the overall resistance in the feature. Resistivity of a tungsten film depends on the thickness of the film deposited, such that resistivity increases as thickness decreases due to boundary effects.

[0031] According to various embodiments, the methods described herein include replacing titanium nitride with molybdenum in metallization stacks that include titanium nitride and tungsten. The titanium nitride is present for tungsten deposition and replaced after tungsten is deposited. In some embodiments, replacing titanium nitride with molybdenum involves a two-stage exposure to molybdenum hexachloride to selectively etch titanium nitride with respect to tungsten and then, by reaction with H2 or other reducing agent, deposit molybdenum.

[0032] The methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon or other semiconductor wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fill any feature with molybdenum. Figure 1 above is provided to illustrate an example of the order of materials in a particular stack and may be used with any appropriate architecture and application, with examples described further below.

[0033] Substrates may have features such as vias or contact holes, which may be characterized by one or more narrow and / or re-entrant openings, constrictions within the feature, and high aspect ratios. A feature may be formed in one or more of the above-described stacks or layers within a stack. For example, the feature may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 5:1, at least about 10: 1, at least about 25: 1, or higher. One example of a feature is a hole orAtorney Docket No. LAM1P096WO-12193-1WO via in a semiconductor substrate or a layer on the substrate.

[0034] Figure 2 shows an example of multiple filled features 210 formed in dielectric layer 204. The dielectric layer may be a low-k dielectric in some embodiments. Each feature is filled with a titanium nitride liner 206 that conformally lines the dielectric sidewalls and bottom of the feature and a tungsten fill layer 208. The architecture in Figure 2 is an example of a metallization stack as shown in Figure 1. In some embodiments, for example, the filled features may be used as contact plugs to connect the M0 layer to underlying devices. The methods may be performed with other structures and applications, including, e.g., laterally-oriented features for memory' applications. Examples of thicknesses for the titanium nitride layer include 3-50 nm. While some of the TiN is covered by W, the TiN is partially exposed, allowing exposure to an etchant. In the example of Figure 2, the TiN is exposed at the top 212 of the TiN liner 206. In some embodiments, a titanium layer may underlie the TiN layer.

[0035] Figure 3 shows operations in a method of replacing the TiN liner with Mo. The method begins with providing a structure including a TiN / W stack in an operation 302. The structure is formed on a wafer or other substrate and may be provided to a processing chamber. In some embodiments, operation 302 may involve maintaining a substrate in a processing chamber after previous processing. The structure generally includes one or more features filled with tungsten and having a titanium nitride liner as discussed above with respect to Figure 2.

[0036] Next, an operation 304, the structure is exposed to molybdenum hexachloride (MoCh) to selectively etch the TiN with respect to the W of the TiN / W stack. Selective etching as used herein refers to etching the TiN at a higher etch rate than the W and may be characterized in terms of etch selectivity. Etch selectivity of TiN with respect to W may range from 25: 1 to 90:1 for MoCh. This means that the TiN is etched between 25 and 90 times faster than the W film.

[0037] To facilitate diffusion of the MoCh into the TiN liner, it may be pulsed into the chamber using one or more charge volumes. A charge volume is a container capable of storing a pressurized volume of process gas. In some embodiments, operation 304 involves multiple cycles of MoCh / purge pulses, in which each cycle includes a MoCh pulse followed by an purge pulse. Argon (Ar) or other inert gas may be used as a purge. Further discussion of gas delivery is provided below.

[0038] At an operation 306, the structure is exposed to MoCh and H2, which react to form metallic (elemental) molybdenum. Molybdenum deposits in the void space where the TiN liner is removed in operation 304, replacing the TiN liner with a Mo liner. Operation 306 can be an atomic layer deposition (ALD) or chemical vapor deposition (CVD) process. In some embodiments, a pulsed CVD process is employed. Pulsed CVD processes are described further below. In some embodiments, operation 306 may also etch TiN that is present deeper within theAtorney Docket No. LAM1P096WO-12193-1WO feature. Molybdenum may also deposit on top of the tungsten surface.

[0039] In Figure 3, operation 304 is a selective etch operation and operation 306 is a deposition operation. According to various embodiments, these may be distinct operations, overlap, or be the same operation. In many embodiments, operation 304 involves exposing the structure to MoCh without H2 or other co-reactant. In this manner, operation 304 is a pure selective etch operation without a deposition component. In such embodiments, operation 304 may be performed until all or only a portion of the TiN liner is etched. In some embodiments, at least some TiN may be left for structural integrity, throughput, and / or other considerations. According to various embodiments, operation 304 may involve etching between 75% and 100% of the total volume of the TiN liner, between 50% and 75% of the total volume of the liner, between 25% and 50% of the total volume of the liner, or between 10% and 25% of the total volume of the liner.

[0040] If during operation 304, only a portion of the TiN liner is selectively etched, some or all the remaining TiN liner may be selectively etched during operation 306. That is, the deposition operation may also selectively etch the TiN. Etching during operation 306 can be modulated by controlling the concentration of the reactants in the feature. Higher Mods flux deeper within the feature can facilitate etching. Charge volumes may be used to deliver pressurized flow of MoCh to increase MoCh concentration and etching deeper into the feature. MoCh may then react with H2 to deposit Mo. According to various embodiments, at the end of operation 306, etching between 90% and 100% of the total volume of the TiN liner, between 75% and 90% of the total volume of the liner, between 50% and 75% of the total volume of the liner, between 25% and 50% of the total volume of the liner, or about 10% to 25% of the total volume of the liner may be replaced with molybdenum.

[0041] During either or both of operations 304 and 306, operating conditions may be adjusted. For example, in some embodiments, in operation 304, in operation 306, or in a combined operation 304 and 306, a MoCh:H2 ratio increased stepwise or continuously increased. The result can be to move from net etch to net deposition, to decrease the etching during a deposition operation, or to increase the deposition during an etching operation.

[0042] Figures 4A-4C shows examples of features at various stages of a process according to Figure 3. Each of Figures 4A-4C shows a structure as shown in Figure 2, including filled features 210 including TiN liners 206. Figure 4A shows a partial selective etch leaving void space 214 between dielectric layer 204 and tungsten fill layer 208. This void space is filled by molybdenum liner 216 after deposition. The result is a liner that is partially TiN and partially Mo, with the Mo liner extending from the top of the filled feature into a fraction of the depth, and the TiN line the bottom and a portion of the sidewalls extending from the bottom of the feature. In Figure 4B, the selective etch is performed to remove almost all the TiN, leaving the TiN liner 206 only at theAtorney Docket No. LAM1P096WO-12193-1WO botom portion of each feature. The remainder of the TiN liner is then removed in the subsequent selective depth and molybdenum liner deposition. The result is a Mo liner 216 in each feature that lines the entire feature, including botom and sidewalls up to the feature top, completely replacing the TiN in the filled features. Figure 4C shows a selective etch and deposition operation that removes a portion of the TiN and replaces it with Mo. In the example of Figure 4C, the void space is continuously formed and filled during the operation.

[0043] The methods described herein are not limited to features filled with tungsten conductive fill layers and titanium nitride liners but may be modified to replace any liner with another material using an etch that is selective to the liner with respect to the conductive fill layer. Examples of etchants can include plasma etchants (e.g., plasma generated from chlorine (Ch)), chlorine dioxide (CIO2), boron trichloride (BCh), carbon tetrachloride (CCh), thionyl chloride (SOCh), sulfur hexafluoride (SFr>). trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PFs), molybdenum pentachloride (MoCb), molybdenum hexafluoride (MoFe), and molybdenum oxytetrachloride (M0OCI4). Other metal halides may be used.

[0044] With TiN / W stacks or other liner / fill combinations, the replacement liner is not limited to molybdenum, but may be any appropriate material, including tungsten. In some embodiments, a molybdenum-containing film (e.g. , molybdenum carbide) is deposited. Similarly, another metalcontaining film (e.g., tungsten nitride) is deposited. Further, in some embodiments, the deposition operation may be modified to change the identities and / or amounts of one or more reactants such that two or more different materials are deposited. For example, more conductive material may be deposited on the feature botom and a less conductive material on the sidewalls of the feature. In depositing molybdenum or a molybdenum-containing liner, MoCb may be used as described above. However, other molybdenum precursors may be used for deposition, including those that do not etch. Deposition of molybdenum and other material is described further below.

[0045] In some embodiments, molybdenum is deposited on the tungsten conductive fill layer in a subsequent operation. Figure 5 shows an example schematic illustration of a side view of a back-end-of-line (BEOL) structure including a conductive tungsten fill layer 508 and molybdenum liner 516 formed as described above. In the example of Figure 5, dielectric material, including silicon oxide and low-k dielectric, as well as etch stop layers (ESE) that were used to form each layer. The botom layer of the feature includes the conductive tungsten fill layer 508 and the molybdenum liner 516.. The M0 layer includes molybdenum. The V0 layer includes copper lined with a diffusion barrier (such as tantalum nitride) and an electromigration barrier layer (such as cobalt, cobalt-ruthenium alloy, ruthenium, or cobalt-doped ruthenium). The Ml layer includes copper lined with a diffusion barrier (such as tantalum nitride) and an electromigration barrier layer (such as cobalt, cobalt-ruthenium alloy, ruthenium, or cobalt-doped ruthenium). In some embodiments,Atorney Docket No. LAM1P096WO-12193-1WO a small amount of molybdenum may be deposited on the tungsten surface during liner layer replacement. The MO layer may incorporate that small amount of molybdenum.

[0046] Pulsed chemical vapor deposition may be used for depositing molybdenum on the conductive fill layer in some embodiments. Examples are provided below with respect to Figures 6-8. Each exposure in an "on” or "‘high” condition may be referred to as a "‘pulse.” For example, pulsing a molybdenum precursor may be depicted as the bolded line for the molybdenum precursor gas being in a lower then a higher horizontal line in temporally alternating pulses. It will be understood that pulsing may involve repetitions of periods, each of which may last a duration T (time). The duration T includes the duration for pulse ON time (the duration for which the gas is in an ON state) and the duration for OFF time (the duration from which the gas is in an OFF state) during a given period. In Figures 6-8, a pulse may be in the “ON’ state when the horizontal line is positioned higher on the y-axis of each row, and a pulse may be in the “OFF” state when the horizontal line is on the x-axis of each row. The pulse frequency will be understood as 1 / T. For example, for a pulsing period T = 100 ps, frequency is 1 / T = l / 100ps, or 10 kHz. The duty cycle or duty ratio is the fraction or percentage in a period T during which the gas is in the ON state such that duty cycle or duty ratio is pulse ON time divided by T. For example, for a pulsing period T = 100 ps, if a pulse ON time is 70 ps (such that the duration for which the gas is in an ON state in a period is 70 ps) and a pulse OFF time is 30 ps (such that the duration for which the gas is in an OFF state in a period is 30 ps), the duty cycle is 70%.

[0047] Figure 6 shows a timing schematic illustration that shows various operations that may be performed in accordance with certain disclosed embodiments. Process 601 includes two deposition cycles 610A and 610B but it will be understood that only one cycle or more than two cycles may be performed in accordance with certain disclosed embodiments. In this example, deposition cycles 610A and 610B include the same operations repeated in each cycle but it will be understood that in some embodiments, various operations, or a variety of operations such as those later described with respect to Figures 7 and 8 may be combined with cycles described here with respect to Figure 6. In the examples in Figures 6-8, during certain phases, gas flow may be pulsed in the “ON” state. In some instances, a phase may correspond to a pulse. The x-axis in each row represents time. Where a gas flow is in the “ON” state, it may be referred to as a “pulse.” Pulses may be temporally separated in that over time, the gas flow will sometimes be in the “ON” state and sometimes in the “OFF” state. When a gas flow is being pulsed in temporally separated pulses, it may also be referred to as being “periodically pulsed” in that in various periods, the gas flow is pulsed. In some cases, a gas flow is pulsed sequentially such that the gas flow is first in the “ON” state then in the “OFF” state then in the “ON” state then in the “OFF” state in that order, which may be repeated. Gas flows may be pulsed in temporally sequential pulses where the sequentialAtorney Docket No. LAM1P096WO-12193-1WO pulses refer to two “ON” states being performed one after another.

[0048] Figure 6 shows various process conditions during each phase - four process conditions are depicted here but it will be understood that other gases, plasma, temperature, pressure, or other conditions may also be present and may vary or be the same across different phases and across different cycles. The process conditions shown in this example include a first hydrogen-containing gas source (which may be a first source of hydrogen gas (H2), a second hydrogen-containing gas source (which may be a second source of hydrogen gas (H2), argon (which may act as a purge gas, carrier gas, inert gas, or any combination thereof), and molybdenum-containing precursor gas.

[0049] In this example, deposition cycle 610A includes four phases - first phase 620A, first purge phase 640 A, second phase 650A, and second purge phase 680A. During first phase 620 A, the first hydrogen source gas is turned on, the second hydrogen gas source is turned on, the argon source is turned off, and the molybdenum precursor gas source is turned off. During this operation only hydrogen-containing gas sources may be flowed.

[0050] During first purge phase 640 A. the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may be turned off or turned down (e.g., low ered flow rate), argon gas source may be turned on, and molybdenum precursor gas source is still turned off.

[0051] During second phase 650A, the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may continue to be off (or on the lower flow rate), argon gas source may be turned off (or have reduced flow rate), and molybdenum precursor gas source is turned on.

[0052] During second purge phase 680A, the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may be still turned off or turned down (e.g., lowered flow rate), argon gas source may be turned on, and molybdenum precursor gas source is turned off.

[0053] While this process flow shows second hydrogen source turned on followed by molybdenum precursor gas turned on, it will be understood that the alternate may be used instead (e.g., molybdenum precursor gas on, then purge, then second hydrogen source on, then purge).

[0054] Deposition cycle 610A is then repeated in deposition cycle 610B. Deposition cycle 610B includes four phases - first phase 620B, first purge phase 640B, second phase 650B, and second purge phase 680B. First phase 620B may be the same as or may be different from first phase 620 A. In this example, first phase 620B is the same as first phase 620A. During first phase 620B, the first hydrogen source gas is still on, the second hydrogen gas source is turned on, the argon source is turned off, and the molybdenum precursor gas source is turned off. During this operation only hydrogen-containing gas sources may be flowed.Atorney Docket No. LAM1P096WO-12193-1WO

[0055] During first purge phase 640B. the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may be turned off or turned down (e.g., lowered flow rate), argon gas source may be turned on, and molybdenum precursor gas source is still turned off.

[0056] During second phase 650B, the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may continue to be off (or on the lower flow rate), argon gas source may be turned off (or have reduced flow rate), and molybdenum precursor gas source is turned on.

[0057] During second purge phase 680B, the first hydrogen source gas may continue to be on (and may continue to be flowed at the same flow rate), the second hydrogen gas source may be still turned off or turned down (e.g., lowered flow rate), argon gas source may be turned on, and molybdenum precursor gas source is turned off.

[0058] Figure 7 shows an alternative deposition cycle scheme that may be used in some embodiments. Figure 7 shows a timing schematic illustration that shows various operations that may be performed in accordance with certain disclosed embodiments. Process 700 includes two deposition cycles 710A and 710B but it will be understood that only one cycle or more than two cycles may be performed in accordance with certain disclosed embodiments. In this example, deposition cycles 710A and 710B include the same operations repeated in each cycle but it will be understood that in some embodiments, various operations, or a variety of operations such as those described with respect to Figures 6 and 8 may be combined with cycles described here with respect to Figure 7.

[0059] Figure 7 shows various process conditions during each phase - three process conditions are depicted here but it will be understood that other gases, plasma, temperature, pressure, or other conditions may also be present and may vary or be the same across different phases and across different cycles. The process conditions shown in this example include a molybdenum-containing precursor gas, a hydrogen-containing gas source (which may be a source of hydrogen gas (H2), and argon (which may act as a purge gas. carrier gas. inert gas, or any combination thereof). In this example, the molybdenum precursor gas source may be continuously flowed.

[0060] In this example, deposition cycle 710A includes four phases - first phase 720A, first purge phase 740 A, second phase 750A, and second purge phase 780A. During first phase 720A, the molybdenum precursor gas is turned on. the hydrogen gas source is turned on, and the argon source is turned off.

[0061] During first purge phase 740A, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned off (or have reduced flow rate), and the argon gas is turned on.Atorney Docket No. LAM1P096WO-12193-1WO

[0062] During second phase 750A, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned on, and the argon gas is turned off (or have reduced flow rate).

[0063] During second purge phase 780 A, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned off (or have reduced flow rate), and the argon gas is turned on.

[0064] While this process flow shows the hydrogen source turned on followed by argon gas turned on, it will be understood that the alternate may be used instead (e.g., purge, then hydrogen source on, then purge, then hydrogen source on).

[0065] Deposition cycle 710A is then repeated in deposition cycle 71 OB. Deposition cycle 71 OB includes four phases - first phase 720B, first purge phase 740B, second phase 750B, and second purge phase 780B. First phase 720B may be the same as or may be different from first phase 720A. In this example, first phase 720B is the same as first phase 720 A. During first phase 720B, the molybdenum precursor gas is turned on. the hydrogen gas source is turned on. and the argon source is turned off.

[0066] During first purge phase 740B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned off (or have reduced flow rate), and the argon gas is turned on.

[0067] During second phase 750B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned on, and the argon gas is turned off (or have reduced flow rate).

[0068] During second purge phase 780B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas may be turned off (or have reduced flow rate), and the argon gas is turned on.

[0069] Figure 8 shows yet another alternative deposition cycle scheme that may be used in some embodiments. Figure 8 shows a timing schematic illustration that shows various operations that may be performed in accordance with certain disclosed embodiments. Process 800 includes two deposition cycles 810A and 81 OB but it will be understood that only one cycle or more than two cycles may be performed in accordance with certain disclosed embodiments. In this example, deposition cycles 810A and 81 OB include the same operations repeated in each cycle but it will be understood that in some embodiments, various operations, or a variety’ of operations such as those described with respect to Figures 6 and 7 may be combined with cycles described here with respect to Figure 8.

[0070] Figure 8 shows various process conditions during each phase - three process conditions are depicted here but it will be understood that other gases, plasma, temperature, pressure, or otherAtorney Docket No. LAM1P096WO-12193-1WO conditions may also be present and may vary or be the same across different phases and across different cycles. The process conditions shown in this example include a hydrogen-containing gas source (which may be a source of hydrogen gas (H2), a molybdenum-containing precursor gas, and argon (which may act as a purge gas, carrier gas, inert gas, or any combination thereof). In this example, the molybdenum precursor gas source may be continuously flowed. In this example, the hydrogen-containing gas source may be continuously flowed.

[0071] In this example, deposition cycle 810A includes four phases - first phase 820A, first purge phase 840 A, second phase 850A, and second purge phase 880A. During first phase 820 A, the molybdenum precursor gas is turned on. the hydrogen gas source is turned on, and the argon source is turned off.

[0072] During first purge phase 840A, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas is still on (and may continue to be flowed at the same flow rate), and the argon gas is turned on.

[0073] During second phase 850A, the molybdenum precursor gas source is still on (and may continue to be 11 owed at the same flow rate), the hydrogen source gas is still on (and may continue to be flowed at the same flow rate), and the argon gas is turned off (or have reduced flow7rate).

[0074] During second purge phase 840A, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas is still on (and may continue to be flow ed at the same flow7rate), and the argon gas is turned on.

[0075] Deposition cycle 810A is then repeated in deposition cycle 81 OB. Deposition cycle 81 OB includes four phases - first phase 820B, first purge phase 840B, second phase 850B, and second purge phase 880B. First phase 820B may be the same as or may be different from first phase 820 A. In this example, first phase 820B is the same as first phase 820A. During first phase 820B, the molybdenum precursor gas is turned on, the hydrogen gas source is turned on, and the argon source is turned off.

[0076] During first purge phase 840B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas is still on (and may continue to be flowed at the same flow rate), and the argon gas is turned on.

[0077] During second phase 850B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas is still on (and may continue to be flowed at the same flow rate), and the argon gas is turned off (or have reduced flow rate).

[0078] During second purge phase 840B, the molybdenum precursor gas source is still on (and may continue to be flowed at the same flow rate), the hydrogen source gas is still on (and may continue to be flowed at the same flow rate), and the argon gas is turned on.

[0079] The molybdenum-containing precursor used to deposit the molybdenum is often M0CI5,Atorney Docket No. LAM1P096WO-12193-1WO but may be any suitable precursor, such as those listed below. The first and / or second hydrogencontaining source gas in various embodiments may be hydrogen gas. Hydrogen gas may continue to flow so as to prevent damage to the substrate when the substrate is exposed to the molybdenum-containing precursor.

[0080] While the Figures 6-8 give examples of pulsed CVD processes that may be employed, in alternate embodiments, other CVD or atomic layer deposition (ALD) cycles may be used.

[0081] Figure 9 shows a timing schematic illustration that shows various operations that may be performed to selectively etch a TiN liner in accordance with certain disclosed embodiments. Process 900 includes four etch cycles 910A-9104 but it will be understood that any number of cycles may be performed in accordance with certain disclosed embodiments. For a selective etch, the number of cycles may be at least 20, 30, 50, 70, or 100, for example, depending on the feature and desired etch depth.

[0082] In this example, etch cycle 910A includes two phases - phase 920A first and purge phase 940A. During phase 920A, MoCls gas is turned on and the argon source is turned off. During purge phase 940A, the molybdenum precursor gas source is off and the argon gas is turned on. Similarly, etch cycles 910B, 910C, and 910D have etch phases 920B, 920C, and 920D, respectively and purge phases 940B, 940C, and 940D, respectively. In the example of Figure 9, the etch phase and purge phase are the same from cycle-to-cycle. According to various embodiments, the etch cycle conditions may be change from cycle-to-cycle as the etch proceeds. Other implementations of the etch may include inert gas and / or etchant flowing continuously. In some embodiments, an etchant soak may be employed without pulsing. These approaches may be used for less aggressive etching than the pulsing.

[0083] In some embodiments, transitioning from an etch cycle to a deposition cycle includes turning on a flow of hydrogen.

[0084] In any one of the above examples with respect to Figures 6-9, the molybdenum precursor gas “on” conditions may involve flowing a molybdenum-containing precursor gas at a flow rate of about 10 seem to about 5000 seem, or about 10 seem to about 1000 seem. In any one of the above examples with respect to Figures 6-8, the first hydrogen gas “on” conditions may involve flowing a hydrogen gas at a flow rate of about 100 seem to about 20000 seem. In any one of the above examples with respect to Figures 6-9, the argon gas “on” conditions may involve flowing an argon gas at a flow rate of about 100 seem to about 10000 seem. The “off” conditions may involve turning flow off (e.g., 0 seem).

[0085] During any one or more etch cycles for etching a liner or one or more deposition cycles for forming molybdenum, the temperature that a pedestal holding the substrate upon which molybdenum is deposited may be set to about 300°C to about 450°C. or about 300°C to aboutAtorney Docket No. LAM1P096WO-12193-1WO 400°C, or less than about 400°C, or less than about 350°C. In some embodiments, the temperature that the pedestal is set at is referred to as a pedestal temperature or a substrate temperature. During any one or more deposition cycles for forming molybdenum, the pressure of a chamber housing the substrate upon which molybdenum is deposited may be about 10 Torr to about 150 Torr.

[0086] In various embodiments, deposition of molybdenum is performed in plasma-free conditions. In some embodiments, deposition of molybdenum is performed without a plasma. In other embodiments, plasma-enhanced processes (e.g., plasma-enhanced ALD) may be used for form molybdenum. A remote or in-situ plasma may be used to generate hydrogen radical species, for example, during the H2 on phases described above.

[0087] Each of the purge operations may be performed for the same duration or different duration. A single deposition cycle may include purge phases of the same duration. A single deposition cycle may include purge phases of different duration. In some embodiments, purging is optional. For example, in some embodiments, throughput may be increased by reducing or eliminating purging, which may not be used depending on the composition of the surface of the substrate. For example, if eliminating purging but performing the overall deposition using the molybdenum-containing precursor still does not damage the substrate, purging can be eliminated to increase throughput.

[0088] In various embodiments, an air break may be incorporated during the process. For example, in some embodiments, prior to depositing molybdenum, a degas operation and hydrogencontaining plasma preclean may be performed. Degas may be used to form an inner ambient having a particular thermal condition to allow moisture to be removed from the substrate and to thereby vaporize gas in the chamber to prepare it for deposition. During degas, the pedestal temperature may be set to about 300°C, and the process chamber pressure may be set to about 7 Torr. During degas, a mixture of argon and helium may be introduced for a duration of about 30 seconds to about 300 seconds. A hydrogen plasma preclean may be performed prior to molybdenum deposition to reduce any formation of oxide that may have formed on an exposed surface.

[0089] Hydrogen plasma preclean may be performed at a temperature of about 150°C to about 300°C. Hydrogen plasma preclean may be performed at a chamber pressure of about 0.01 Torr to about 10 Torr. Hydrogen plasma preclean may be performed using a flow rate of hydrogen gas of about 25 seem to about 5000 seem. Hydrogen plasma preclean may be performed for a duration of about 10 seconds to about 120 seconds. Hydrogen plasma preclean may be performed before everj^ deposition cycle or before any deposition cycles or before certain deposition cycles. Plasma conditions during preclean may be as follows: single or dual frequency plasma, plasma power of about 100W to about 3000W, and plasma frequency of about 13 MHz to about 27 MHz. In someAtorney Docket No. LAM1P096WO-12193-1WO embodiments, plasma preclean may be pulsed, such as with a duty cycle of about 10% to about 50%.

[0090] In various embodiments, soaking with a molybdenum-containing precursor gas may be performed prior to depositing molybdenum so as to decompose molybdenum thermally on a surface of the feature. Such embodiments may help increase nucleation and reduce nucleation delay of molybdenum when it is deposited subsequently using pulsed chemical vapor deposition techniques such as described herein. Soaking may be performed at a temperature of about 100°C to about 350°C. Soaking may be performed at a chamber pressure of about 0.5 Torr to about 150 Torr. Soaking may be performed using a flow rate of about 10 seem to about 5000 seem. Soaking may be performed for a duration of about 1 second to about 300 seconds. Soaking may be performed before every deposition cycle or before any deposition cycles or before certain deposition cycles.

[0091] According to various embodiments, any of the pulses described above may be delivered with a charge volume. In some embodiments, multiple charge volumes may be used for a pulse. Figure 10 depicts a pressure time graph of a pulse operation using a single charge volume (also referred to as an accumulator). Figure 11 depicts a pressure time graph of a pulse operation using multiple charge volumes. In Figure 10, a charge volume is used to build a pressurized volume of purge gas, which is then flowed into the process chamber. The charge volume has an initial pressure, baseline pressure 1002, which acts as a baseline pressure of the charge volume. Slope 1004 shows the increase in pressure of the volume in the charge volume as the gas is pressurized. In Figure 11 the charge volume reaches a maximum pressure of about 550 Torr before the gas is flowed to the chamber, but the pressure in the charge volume may vary from about 400 Torr to about 1 00 Torr. Then, at time 1006 the gas is flowed into the chamber, and the pressure rapidly decreases as gas flows out of the charge volume. The decrease in pressure of the charge volume corresponds with an increased flow of gas into the chamber. As the gas volume is flowed into the chamber, the pressure in the charge volume returns to baseline pressure 1002. The charge may then increase pressure and flow gas into the chamber for a pulse in another cycle (not shown).

[0092] Figure 11 represents a rapid pulse operation. A first charge volume and a second charge volume are used to flow gas into the chamber. Similar to Figure 11, both charge volumes have a baseline pressure 1012. Then, the first charge volume is pressurized as shown by slope 1014. At time 1016 the gas from the first charge volume is flowed into the chamber, resulting in a rapid decrease in pressure in the first charge volume. The decrease in pressure of the charge volume corresponds with an increased mass flow of gas into the chamber. As the pressure in the first charge volume decreases, the mass flow of gas into the chamber will also decrease. Then, at time 1017, the second charge volume flows gas into the chamber. The second flow of pressurized gas againAtorney Docket No. LAM1P096WO-12193-1WO increases the mass flow of gas into the chamber. By using two charge volumes, the average mass flow into the chamber is increased. For purge operations, for example, this can increase the rate of removal of reactant gases, and decreasing the total time required to purge the chamber.Molybdenum Deposition

[0093] Deposition of molybdenum as described herein involves reacting a Mo-containing precursor, also referred to as a molybdenum precursor. As described above, MoCh may be used for selective etch in some embodiments. In other embodiments, other metal halides or other etchants may be used.

[0094] In embodiments in which MoCh is used to etch, it is often used to deposit molybdenum as the transition from etch to deposition is relatively easy. However, for other etchants and / or for other reasons, other precursors may be used. The deposition techniques described below may be used for deposition of a Mo layer above the filled feature after liner deposition.

[0095] In some embodiments, a Mo precursor is a molybdenum chloride (MoClx) compound also referred to as a molybdenum chloride precursor or MoClx precursor. Molybdenum chloride precursors are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (MoCh), molybdenum trichloride (MoCh), molybdenum tetrachloride (MoCfi), molybdenum pentachloride (MoCh), and molybdenum hexachloride (Mode). In some embodiments, MoCh or MoCh are used. While the description chiefly refers to MoClx precursors, in other embodiments, other molybdenum halide precursors may be used. Molybdenum halide precursors are given by the formula MoXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and z is 2, 3, 4, 5, or 6. Examples of MoXzprecursors include molybdenum fluoride (MoFe). In some embodiments, a non-fluorine-containing MoXz precursor is used to prevent fluorine etch or incorporation. In some embodiments, anon-bromine-containing and / or a non-iodine-containing MoXz precursor is used to prevent etch or bromine or iodine incorporation.

[0096] In some embodiments, the feature may be filled using a molybdenum oxyhalide precursor. Molybdenum oxyhalide precursors are given by the formula MoOyXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0 such that MoOyXzforms a stable compound. Examples of molybdenum oxyhalides include molybdenum dichloride dioxide (MOO2CI2), molybdenum tetrachloride oxide (MoOCh), molybdenum tetrafluoride oxide (M00F4), molybdenum dibromide dioxide (MoChBn), and the molybdenum iodides MOO2I, and MO4O11I. It should be understood that as used herein the term molybdenum oxyhalide precursor may refer to a molybdenum oxyhalide precursor as described above or a molybdenum-containing oxyhalide precursor that includes molybdenum, oxygen, a halide and one or more other elements. In some embodiments, molybdenum oxyhalide orAtorney Docket No. LAM1P096WO-12193-1WO molybdenum-containing oxyhalides may include multiple different halogens (e.g., F and Cl and / or I and / or Br, etc.). A feature may be filled with molybdenum using a MoXxprecursor, MoOyXzprecursor, or a combination thereof.

[0097] A molybdenum precursor may be provided in a carrier gas, e.g., Ar in some embodiments. As an example, MOO2CI2 may be provide as 10%(vol) in a process gas with the balance being argon. Reference to partial pressure of the precursor in this document refer to the precursor only, and not the carrier gas.

[0098] For deposition of molybdenum into the feature, the molybdenum precursor may be reacted with a co-reactant. Examples of co-reactants include hydrogen (H2), silane (SiFU), diborane (B2H6), germane (GeH-i). ammonia (NH3), and hydrazine (N2H4). Ammonia and hydrazine may be used to deposit molybdenum nitrides or molybdenum oxynitrides.

[0099] In some embodiments, deposition of molybdenum may use a plasma-based process. Gas may be fed into a remote or in-situ plasma generator to generate plasma species. Examples of gas that may be used to generate plasma may be a hydrogen-containing gas, such as H2. nitrogencontaining gas, such as nitrogen (N2) and other gases, such as Ar and NFL. The plasma species may be inert or react with the molybdenum precursor to form a film.

[0100] A feature may be filled with molybdenum by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma enhanced ALD (PEALD) may be used. Similarly, thermal CVD or plasma enhanced CVD (PECVD) may be used.

[0101] ALD is a surface-mediated deposition technique in which doses of a precursor and a reactant are sequentially introduced into a deposition chamber. One or more cycles of sequential doses of a molybdenum precursor and reactant may be used to deposit Mo. For example, in the deposition of an initial molybdenum layer, M0CI5 may be used as a precursor and H2 as a reducing agent. Doses of M0CI5 and H2 are sequentially introduced into the deposition chamber with a purge gas, such as argon, flowed between. For ALD, the temperature of the substrate and the pressure of the chamber may be controlled. For example, the substrate may be heated between 200°C and 800°C, e.g., between 250°C and 550°C or between 300°C and 500°C between 350°C and 450°C. In some embodiments, the chamber may be pressurized between 10 Torr and 200 Torr, e.g., between 50 Torr and 90 Torr. In some embodiments, the temperature and / or pressure may be used to control the rate of reactions. In some embodiments, the temperature and / or pressure may be used to control selectivity.

[0102] In some embodiments, the Mo precursor is a molybdenum fluoride (MoFx) compound, also referred to as a molybdenum fluoride precursor or MoFxprecursor. Molybdenum fluoride precursors are given by the formula MoFx, where x is 4, 5, or 6, and include molybdenum tetrafluoride (M0F4), molybdenum pentafluoride (M0F5), and molybdenum hexafluoride (MoFs).Atorney Docket No. LAM1P096WO-12193-1WO

[0103] MoFe can be advantageous as it has a boiling point of 34°C. Being a gas at standard pressure and 35°C allows MoFe to be delivered through a mass flow controller (MFC) at room temperature, without heating and without condensing and forming particles. However MoFe is an aggressive etchant and exposure to MoFe during a process can result in etching instead of or in addition to Mo deposition. In some embodiments, deposition using MoFe involves providing a flow of MoFe in a process gas with the MoFe at a molar concentration of 0.01% or less. Concentration may be significantly lower in some embodiments, for example, 0.008% or less, 0.005% or less, or 0.004% or less. These values can also be expressed as parts per million (ppm) of a gas: 100 ppm (100 MoFe molecules per 1 million gas particles (atoms, molecules)) or less, 80 ppm or less, or 40 ppm or less. At temperatures between 200°C and 650°C, for example, a molar concentration at or below 0.004% results in CVD deposition when flowed with H2 and argon. Higher temperatures may be used to favor the deposition reaction and allow higher concentrations of M0F6, e.g., up to 0.01%. In some embodiments, concentrations may be 0.0039% or .0035% or less. In some embodiments, the MoFe concentration is at least 0.00004% or at least 0.0001%. Concentration may be very low with an exposed metal surface to grow on, for example.

[0104] Deposition using MoFe with H2 as reducing agent occurs only at unusually low concentration. As an example, for 0.5 seem of MoFe, a total flow rate of 13,500 seem may be used, for a MoFe concentration of 0.0037%. Deposition using metal halides and hydrogen generally involves much higher concentrations. For example, deposition of molybdenum using molybdenum hexachloride and hydrogen can be performed using concentrations 5 to 10 times higher than those used for MoFe.

[0105] In some embodiments, MoFe may be used at higher concentrations and lower temperatures with a reducing agent that is stronger than that of hydrogen. Lower temperatures can reduce or prevent etching with MoFe; however, at low temperatures H2 may not result in deposition. Stronger reducing agents such silane, disilane, polysilanes and diborane may be used for deposition at lower temperatures (e g., below 200°C). The resulting films may not be pure molybdenum and in some cases are more resistive than those deposited using H2 as the reducing agent. For these reasons they may not be appropriate for some applications.

[0106] In some embodiments, molybdenum fill may involve CVD. In a CVD process, the molybdenum precursor and reactant are in vapor phase together in the deposition chamber. Generally speaking, a CVD process fills a feature faster than an ALD process. In one example, the precursor may be a molybdenum oxychlonde, such as MOO2CI2, and is flowed into the chamber with a reactant, such as H2. In this example, the wafer is simultaneously exposed to the precursor and reactant, which react and fill features with Mo. In one example, MoFe is flowed into the chamber with a reactant, such as H2. In this example, the wafer is simultaneously exposed to theAtorney Docket No. LAM1P096WO-12193-1WO precursor and reactant, which react and fill features with Mo.

[0107] In still some other embodiments, a feature may be filled using a pulsed CVD process. The pulsed CVD process continuously flows a reactant into a chamber while pulses of a precursor flow into the chamber. For example, H2 gas may be flowed into the chamber and is continuously flowing into the chamber while the molybdenum-containing precursor is intermittently flowing into the chamber. The temperature of the substrate and pressure in the chamber may be controlled during a CVD operation.

[0108] Plasma-enhanced CVD may be used in which a plasma is ignited during the deposition. In a pulsed CVD process, a plasma may be ignited during deposition cycle or during, e.g., pulses of the hydrogen reactant. In some embodiments, a remote plasma may be used. The plasma may be remotely-generated or direct. Further it may be generated by any appropriate plasma generator including a capacitively-coupled plasma generator or an inductively -coupled plasma generator. A microwave plasma generator may be used.

[0109] In addition to the molybdenum halides and molybdenum oxyhalides described herein, the molybdenum films may be deposited using organometallic and / or sulfur-containing precursors. Organometallic molybdenum-containing compounds and / or sulfur-containing molybdenum-containing compounds may be used as molybdenum precursors in some embodiments. Examples of these are given in PCT publication W02023250500, incorporated by reference herein.APPARATUS

[0110] The methods described herein can be carried out in a variety of apparatuses. A suitable apparatus includes a processing chamber having one or more inlets for introduction of reactants, a substrate holder in the process chamber configured to hold the substrate in place during deposition, and, optionally, a plasma generating mechanism configured for generating a plasma in a process gas. The apparatus may include a controller having program instructions for causing any of the method steps described herein. The deposition methods described herein may be carried out in corresponding atomic layer deposition (ALD) and chemical vapor deposition (CVD) apparatuses.[OlH] For example, in some embodiments the apparatus includes a controller having program instructions that include instructions for: causing an introduction of a molybdenum-containing precursor to the processing chamber causing selective etch of TiN. It may further have instructions for: causing a reaction between the molybdenum-containing precursor and hydrogen-containing gas to form a layer of molybdenum-containing material on a substrate. The controller may include program instructions for causing any of the methods described herein.

[0112] An example of a deposition apparatus suitable for depositing molybdenum-containing films using provided methods is shown in Figure 12A which schematically illustrates anAtorney Docket No. LAM1P096WO-12193-1WO embodiment of a process station 1200 that may be used to deposit material using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), either of which may be plasma enhanced. In various embodiments, process station 1200 is used for pulsed chemical vapor deposition (pCVD). Process station 1200 may also be used for selective etch. For simplicity, the process station 1200 is depicted as a standalone process station having a process chamber body 1202 for maintaining a low-pressure environment. However, it will be appreciated that a plurality of process stations 1200 may be included in a common process tool environment. Further, it will be appreciated that, in some embodiments, one or more hardware parameters of process station 1200. including those discussed in detail below, may be adjusted programmatically by one or more computer controllers.

[0113] Figure 12A depicts a schematic illustration of an embodiment of an ALD process station 1200 having a process chamber body 1202 for maintaining a low-pressure environment. In some embodiments, a plurality of ALD process stations may be included in a common low-pressure process tool environment. For example. Figures 13A and 13B (described below) depict embodiments of a system 1300 that includes a multi-station and / or multi-chamber processing tool. In some embodiments, one or more hardware parameters of ALD process station 1200, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 1250. In some other embodiments, a process chamber may be a single station chamber.

[0114] ALD process station 1200 fluidly communicates with reactant deliver}' system 1201a for delivering process gases to a distribution showerhead 1206. Reactant delivery system 1201a includes a mixing vessel 1204 for blending and / or conditioning process gases, such as a Mo precursor-containing gas, a hydrogen-containing gas, an argon or other carrier gas, or other reactant-containing gas, for delivery to showerhead 1206. One or more mixing vessel inlet valves 1220 may control introduction of process gases to mixing vessel 1204. In various embodiments, etch of TiN occurs in process station 1200 and in some embodiments, other operations such as deposition of Mo to replace the TiN liner may be performed in the same or another station of a multi-station processing tool as further described below with respect to Figure 13 A.

[0115] As an example, the embodiment of Figure 12A includes a vaporization point 1203 for vaporizing liquid reactant to be supplied to the mixing vessel 1204. In some embodiments, vaporization point 1203 may be a heated vaporizer. In some embodiments, a liquid precursor or liquid reactant may be vaporized at a liquid injector (not shown). For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel 1204. In one embodiment, a liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. SmallerAtorney Docket No. LAM1P096WO-12193-1WO droplets may vaporize faster than larger droplets, reducing a delay between liquid injection and complete vaporization. Faster vaporization may reduce the length of piping downstream from vaporization point 1203. In one scenario, a liquid injector may be mounted directly to mixing vessel 1204. In another scenario, a liquid injector may be mounted directly to showerhead 1206.

[0116] Reactant delivery system 1201a may also include one or more solid precursor delivery components including one or more on-board ampoules 1213 and / or bulk delivery components 1215.

[0117] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 1203 may be provided for controlling a mass flow of liquid for vaporization and delivery to process chamber body 1202. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. How ever, it may take one second or more to stabilize liquid flow using feedback control. This may extend a time for dosing a liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, this may be performed by disabling a sense tube of the LFC and the PID controller.

[0118] Showerhead 1206 distributes process gases toward substrate 1212. In the embodiment shown in Figure 12A, the substrate 1212 is located beneath showerhead 1206 and is shown resting on a pedestal 1208. Showerhead 1206 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to substrate 1212.

[0119] In some embodiments, pedestal 1208 may be raised or lowered to expose substrate 1212 to a volume between the substrate 1212 and the showerhead 1206. In some embodiments, pedestal 1208 may be temperature controlled via heater 1210. Pedestal 1208 may be set to any suitable temperature, such as between about 200°C and about 800°C during operations for performing various disclosed embodiments. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller 1250. At the conclusion of a process phase, pedestal 1208 may be lowered during another substrate transfer phase to allow removal of substrate 1212 from pedestal 1208.

[0120] In some embodiments, a position of showerhead 1206 may be adjusted relative to pedestal 1208 to vary a volume between the substrate 1212 and the showerhead 1206. Further, it will be appreciated that a vertical position of pedestal 1208 and / or showerhead 1206 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1208 may include a rotational axis for rotating an orientation of substrate 1212. It will be appreciated that, in some embodiments, one or more of these example adjustments may beAtorney Docket No. LAM1P096WO-12193-1WO performed programmatically by one or more suitable computer controllers 1250.

[0121] In some embodiments where plasma may be used as discussed above, showerhead 1206 and pedestal 1208 electrically communicate with a radio frequency (RF) power supply 1214 and matching network 1216 for powering a plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example, RF power supply 1214 and matching network 1216 may be operated at any suitable power to form a plasma having a desired composition of ionic and / or radical species. Likewise, RF power supply 1214 may provide RF power of any suitable frequency. In some embodiments, RF power supply 1214 may be configured to control high- and low-frequency RF power sources independently of one another. Example low-frequency RF frequencies may include, but are not limited to, frequencies between 0 kHz and 900 kHz. Example high-frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz, or greater than about 13.56 MHz, or greater than 27 MHz. or greater than 80 MHz. or greater than 60 MHz. It will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for the surface reactions. In some embodiments, the showerhead is powered and the pedestal is grounded. In some embodiments, the pedestal is powered.

[0122] In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0123] In some embodiments, instructions for a controller 1250 may be provided via input / output control (IOC) sequencing instructions. In one example, the instructions for setting conditions for a process phase may be included in a corresponding recipe phase of a process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe phase. For example, a first recipe phase may include instructions for setting a flow rate of a molybdenum precursor (e.g., MoCh) and a carrier gas and time delay instructions for the first recipe phase. AAtorney Docket No. LAM1P096WO-12193-1WO second, subsequent recipe phase may include instructions for modulating or stopping a flow rate of these gases, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the second recipe phase. . It will be appreciated that these recipe phases may be further subdivided and / or iterated in any suitable way within the scope of the present disclosure.

[0124] Further, in some embodiments, pressure control for process station 1200 may be provided by butterfly valve 1218. As shown in the embodiment of Figure 12A, butterfly valve 1218 throttles a vacuum provided by a downstream vacuum pump (not shown). How ever, in some embodiments, pressure control of process station 1200 may also be adjusted by varying a flow7rate of one or more gases introduced to the process station 1200.

[0125] Any of the stations described herein may include charge volumes. An example apparatus is shown in Figure 12B, in which 3 gas sources (Mods, H2, and purge gases) are connected to charge volumes.

[0126] Figures 13 A and 13B show examples of processing systems. Figure 13A shows an example of a processing system including multiple chambers. The system 1300 includes a transfer module 1303. The transfer module 1303 provides a clean, vacuum environment to minimize risk of contamination of substrates being processed as they are moved between various modules. Mounted on the transfer module 1303 is a multi-station chamber 1309 capable of performing ALD processes described above.

[0127] Also mounted on the transfer module 1303 are one or more single station modules 1307a and 1307b. In some embodiments, an optional preclean is performed in a module 1307a with the selective etched performed in module 1307b. Deposition of molybdenum may be performed in chamber 1309. In some embodiments, multiple stations 1311, 1313, 1315, and 1317 that may sequentially perform operations in accordance with disclosed embodiments. The multi-station chamber 1309 may also be operated in static mode such that the same deposition occurs in parallel on different substrates. In another example, both selective etch and subsequent deposition are performed in multi-station chamber 1309.

[0128] Two or more stations may be included in a multi-station chamber, e.g.. 2-6, with the operations appropriately distributed. For example, a two-station chamber may be configured to perform pCVD of the Mo liner replacement layer in a first station followed by ALD of bulk metal in a second station. Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0129] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0130] The system 1300 also includes one or more wafer source modules 1301, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmosphericAtorney Docket No. LAM1P096WO-12193-1WO transfer chamber 1319 may first remove wafers from the source modules 1301 to loadlocks 1321. A wafer transfer device (generally a robot arm unit) in the transfer module 1303 moves the wafers from loadlocks 1321 to and among the modules mounted on the transfer module 1303.

[0131] Chamber 1309 may have one or more of the following features:Individually addressable plasma power generators associated with each station;Individually addressable reactant inputs associated with each station;Multi-plenum showerheads on each station;Dual solid precursor delivery systems.

[0132] Solid precursor delivery systems may include bulk delivery systems and / or on-board ampoules.

[0133] Figure 13B is an embodiment of a system 1300. The system 1300 in Figure 13B has wafer source modules 1301, a transfer module 1303, atmospheric transfer chamber 1319. and loadlocks 1321, as described above with reference to Figure 13A. The system in Figure 13B has three single station modules 1357a-1375c. The system 1300 may be configured to sequentially perform operations in accordance with the disclosed embodiments. For example, the single station modules 1357a-1357c may be configured so that a first module 1357a does a selective etch, a second module 1357b does a surface treatment, and module 1357c performs deposits molybdenum. In accordance with the embodiments disclosed above, any of the modules in Figures 13 A and 13B may be configured to perform etch.

[0134] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate as described above with reference to Figure 12A.

[0135] Returning to Figure 13A and 13B, in various embodiments, a system controller 1329 is employed to control process conditions during deposition. The controller 1329 will typically include one or more memory' devices and one or more processors. A processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. Such a system controller may be employed in control of any of the processes and apparatus described herein.

[0136] The controller 1329 may control all the activities of the apparatus. The system controller 1329 executes system control software, including sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory devices associated with the controller 1329 may be employed in some embodiments.

[0137] Typically, there will be a user interface associated with the controller 1329. The userAtorney Docket No. LAM1P096WO-12193-1WO interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0138] System control logic may be configured in any suitable way. In general, the logic can be designed or configured in hardware and / or software. The instructions for controlling the drive circuitry may be hard coded or provided as software. The instructions may be provided by “programming.” Such programming is understood to include logic of any form, including hard coded logic in digital signal processors, application-specific integrated circuits, and other devices which have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general-purpose processor. System control software may be coded in any suitable computer readable programming language.

[0139] The computer program code for controlling the Mo precursor pulses, hydrogen pulses, and argon flow, and other processes in a process sequence can be written in any conventional computer readable programming language: for example, assembly language, C. C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program. Also as indicated, the program code may be hard coded.

[0140] The controller parameters relate to process conditions, such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe and may be entered utilizing the user interface.

[0141] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1329. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

[0142] The system software may be designed or configured in many w ays. For example, various chamber component subroutines or control objects may be written to control operation of the chamber components necessary to carry out the deposition processes in accordance with the disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0143] In some implementations, a controller 1329 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as theAtorney Docket No. LAM1P096WO-12193-1WO “controller ’ which may control various components or subparts of the system or systems. The controller 1329, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0144] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for cartying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0145] The controller 1329, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller 1329 may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. The parameters may be specific to the type of process to be performed and the ty pe of tool that the controller is configured to interface with or control. Thus, as described above, the controller mayAtorney Docket No. LAM1P096WO-12193-1WO be distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0146] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a PVD chamber or module, a CVD chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0147] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0148] The controller 1329 may include various programs. A substrate positioning program may include program code for controlling chamber components that are used to load the substrate onto a pedestal or chuck and to control the spacing between the substrate and other parts of the chamber such as a gas inlet. A substrate tilt and rotation program may include code for tilt and rotation. A process gas control program may include code for controlling gas composition, flow rates, pulse times, and optionally for flowing gas into the chamber prior to deposition in order to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber by regulating, e.g., a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating unit that is used to heat the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas such as helium to the wafer chuck.

[0149] Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as manometers, and thermocouples located in the pedestal or chuck. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain desired process conditions.

[0150] The foregoing describes implementation of disclosed embodiments in a single or multichamber semiconductor processing tool. The apparatus and process described herein may be usedAtorney Docket No. LAM1P096WO-12193-1WO in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels, and the like. Typically, though not necessarily, such tools / processes will be used or conducted together in a common fabrication faci 1 i ty. Lithographic patterning of a film typically includes some or all of the following steps, each step provided with a number of possible tools: (1) application of photoresist on a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curing of photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern into an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.Implementations

[0151] Implementation 1. A method comprising: providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a liner layer disposed between the conductive fill material and the dielectric layer to line the feature; and replacing at least some of the liner layer with molybdenum while leaving the conductive fill material substantially intact.

[0152] Implementation 2. The method of implementation 1, wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to a molybdenum-containing etchant to selectively etch the liner layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material.

[0153] Implementation 3. The method of implementation 2, wherein replacing at least some of the liner layer with molybdenum comprises exposing the substrate to a molybdenum-containing precursor to deposit molybdenum in the void.

[0154] Implementation 4. The method of implementation 3, wherein the molybdenum-containing etchant and the molybdenum-containing precursor are same molybdenum-containing compound or are generated from the same molybdenum-containing compound.

[0155] Implementation 5. The method of implementation 2, wherein the molybdenum-containing etchant is molybdenum pentachloride (MoC15).

[0156] Implementation 6. The method of implementation 3, wherein depositing molybdenum in the void at least partially overlaps selectively etching the liner layer.

[0157] Implementation 7. The method of implementation 1, wherein the conductive fill material is tungsten and the liner layer is titanium nitride.

[0158] Implementation 8. The method of implementation 7, wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to a MoC15 to selectively etchAtorney Docket No. LAM1P096WO-12193-1WO the liner layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material.

[0159] Implementation 9. The method of implementation 1, wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to an etchant to selectively etch the liner layer with respect to the conductive fill material.

[0160] Implementation 10. The method of implementation 9, wherein the etchant is one of or is a plasma generated from one of: chlorine (C12), chlorine dioxide (C1O2), boron trichloride (BC13), carbon tetrachloride (CC14), thionyl chloride (SOC12), sulfur hexafluoride (SF6), trifluorochloride (C1F3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum hexafluoride (MoF6), or molybdenum oxytetrachloride (MoOC14).

[0161] Implementation 11. A method comprising: providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a titanium nitride liner layer disposed between the conductive fill material and the dielectric layer to line the feature; and exposing the substrate to molybdenum pentachloride (MoC15) to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact.

[0162] Implementation 12. The method of implementation 11, wherein exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact comprises a first phase in which the substrate is exposed to multiple cycles of alternating molybdenum pentachloride and purge gas without exposure to hydrogen during or between the multiple cycles.

[0163] Implementation 13. The method of implementation 12, wherein exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact comprises a second phase in which the substrate is exposed to molybdenum pentachloride and hydrogen.CONCLUSION

[0164] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

Atorney Docket No. LAM1P096WO-12193-1WO CLAIMSWhat is claimed is:

1. A method comprising:providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a liner layer disposed between the conductive fill material and the dielectric layer to line the feature; andreplacing at least some of the liner layer with molybdenum while leaving the conductive fill material substantially intact.

2. The method of claim 1, wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to a molybdenum-containing etchant to selectively etch the liner layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material.

3. The method of claim 2, wherein replacing at least some of the liner layer with molybdenum comprises exposing the substrate to a molybdenum-containing precursor to deposit molybdenum in the void.

4. The method of claim 3. wherein the molybdenum-containing etchant and the molybdenum-containing precursor are same molybdenum-containing compound or are generated from the same molybdenum-containing compound.

5. The method of claim 2. wherein the molybdenum-containing etchant is molybdenum pentachloride (M0CI5).

6. The method of claim 3. wherein depositing molybdenum in the void at least partially overlaps selectively etching the liner layer.

7. The method of claim 1. wherein the conductive fdl material is tungsten and the liner layer is titanium nitride.

8. The method of claim 7, wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to a MoCls to selectively etch the linerAtorney Docket No. LAM1P096WO-12193-1WO layer with respect to the conductive fill material, thereby leaving a void between the dielectric layer and the conductive fill material.

9. The method of claim 1. wherein replacing at least some of the liner layer with molybdenum comprises exposing the liner layer to an etchant to selectively etch the liner layer with respect to the conductive fill material.

10. The method of claim 9, wherein the etchant is one of or is a plasma generated from one of: chlorine (Ch), chlorine dioxide (CIO2), boron trichloride (BCh), carbon tetrachloride (CCI4), thionyl chloride (SOCh), sulfur hexafluoride (SFe), trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum hexafluoride (MoFs). or molybdenum oxytetrachloride (MoOCh).

11. A method comprising:providing a substrate having a feature formed in a dielectric layer, wherein the feature is filled with a conductive fill material and a titanium nitride liner layer disposed between the conductive fill material and the dielectric layer to line the feature; andexposing the substrate to molybdenum pentachloride (MoCb) to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact.

12. The method of claim 11, wherein exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact comprises a first phase in which the substrate is exposed to multiple cycles of alternating molybdenum pentachloride and purge gas without exposure to hydrogen during or between the multiple cycles.

13. The method of claim 12, wherein exposing the substrate to molybdenum pentachloride to replace at least some of the titanium nitride liner layer with molybdenum while leaving the conductive fill material substantially intact comprises a second phase in which the substrate is exposed to molybdenum pentachloride and hydrogen.

Images