Incorporation of non-metal in molybdenum on dielectric body surface

Abstract

To provide a low-resistance metallization stack structure for a three-dimensional NAND application, and a related manufacturing method.SOLUTION: A thin metal oxynitride nucleation layer 108 is deposited on a dielectric material 104, then a pure metal conductor 110 is deposited using a process condition of increasing a content of a non-molybdenum component element on an oxynitride-dielectric body boundary. In a specific embodiment, a resistivity is further reduced by converting less than all of the metal oxynitride nucleation layer to a pure metal layer.SELECTED DRAWING: Figure 4

Description

Incorporation by Reference

[0001] A PCT application is filed concurrently herewith as part of the present application. Each application identified in the concurrently filed PCT application to which this application claims benefit or priority is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002] The deposition of tungsten (W) films using chemical vapor deposition (CVD) techniques is an essential part of semiconductor manufacturing processes. For example, W films can be used as low-resistance electrical connections in the form of horizontal interconnects, vias between adjacent metal layers, and contacts between the first metal layer and devices on silicon substrates. Tungsten films can also be used in various memory applications, such as forming buried wordline (bWL) architectures for dynamic random access memory (DRAM), wordlines for 3D NAND, and logic applications. However, the ever-decreasing feature sizes and film thicknesses pose various challenges, such as high resistivity, for further thinning. Other metals, such as molybdenum (Mo), are being evaluated as low-resistivity W substitutes.

[0003] The background discussion provided herein is intended to provide a general background to the present disclosure. Work by the inventors named herein, to the extent described in this Background section, as well as aspects of the description that may not be considered prior art at the time of filing, are not admitted expressly or implicitly as prior art against the present disclosure. Summary of the Invention

[0004] Provided herein are methods and apparatus for processing a substrate. One embodiment includes a method for processing a substrate, the method comprising: providing a substrate having an oxide material thereon; exposing the oxide material to alternating pulses of a first oxygen-containing molybdenum precursor and a first reducing agent using a first set of process conditions to deposit at least a portion of an elemental molybdenum layer over the oxide material using a first atomic layer deposition (ALD) process; and adjusting the first set of process conditions to increase the non-molybdenum content when depositing the portion of the elemental molybdenum layer.

[0005] In various embodiments, the first set of process conditions includes using a first reducing agent at a flow rate of at least about 1000 sccm during the first ALD process.

[0006] In various embodiments, the first set of process conditions includes exposing the substrate to a first reducing agent for at least 1 second during one cycle of the first ALD process.

[0007] In various embodiments, the method also includes exposing the oxide material to a soak gas, such as a boron-containing gas, a tungsten-containing gas, a fluorine-containing gas, an oxygen-containing gas, a chlorine-containing gas, and combinations thereof, prior to depositing a portion of the elemental molybdenum layer.

[0008] In various embodiments, the method also includes exposing the oxide material to alternating pulses of a boron-containing gas and a tungsten-containing gas prior to depositing a portion of the elemental molybdenum layer, hi some embodiments, the boron-containing gas includes diborane and the tungsten-containing gas includes tungsten hexafluoride.

[0009] In various embodiments, the method also includes, prior to depositing a portion of the elemental molybdenum layer, depositing the first layer on the oxide material using a second ALD process under a second set of process conditions using a second oxygen-containing molybdenum precursor and a second reducing agent. In some embodiments, the second reducing agent is a nitrogen-containing gas, hydrogen, or a combination thereof.

[0010] In some embodiments, the second set of process conditions comprises depositing at least a portion of the elemental molybdenum layer at a substrate temperature of less than about 400° C. In some embodiments, at least one of the first oxygen-containing molybdenum precursor and the second oxygen-containing molybdenum precursor is a molybdenum oxyhalide. In some embodiments, the first oxygen-containing molybdenum precursor is a molybdenum oxyhalide, and the first set of process conditions comprises using a hydrogen to molybdenum oxyhalide precursor ratio of between about 100:1 and about 10,000:1.

[0011] In some embodiments, the second set of process conditions includes increasing the flow of a nitrogen-containing gas during the second ALD process.

[0012] In some embodiments, the method also includes flowing nitrogen during deposition of the first layer.

[0013] In some embodiments, the method also includes soaking the substrate having the oxide material thereon with a soak gas before depositing the first layer, which may be any one or more of oxygen, ammonia, or nitrogen.

[0014] In some embodiments, the method also includes soaking the substrate having the oxide material thereon with a soak gas after depositing the first layer.

[0015] In some embodiments, less than half of the first layer is converted to a converted elemental molybdenum layer during or before the first ALD process. The converted elemental molybdenum layer may contain more than 1 atomic percent impurities. The impurities may be oxygen, chlorine, nitrogen, or combinations thereof.

[0016] In various embodiments, the first layer is a crystalline layer.

[0017] In various embodiments, the first layer is an amorphous layer.

[0018] In various embodiments, the first ALD process and the second ALD process are performed in the same chamber without exposure to air.

[0019] In various embodiments, the first layer is a template for metal grain growth in the elemental molybdenum layer.

[0020] In various embodiments, the second ALD process is performed at a temperature less than 400° C. In some embodiments, the first ALD process is performed at the same temperature as the second ALD process. In some embodiments, the elemental molybdenum layer is a graded film such that at least a first set of cycles of the first ALD process are performed at a temperature less than about 400° C. and at least a last set of cycles of the first ALD process are performed at a temperature greater than 400° C.

[0021] In various embodiments, the deposition of the first layer and the deposition of the elemental molybdenum layer are performed in the same chamber, hi some embodiments, the deposition of the first layer and the deposition of the elemental molybdenum layer are performed in separate stations of the same chamber.

[0022] In various embodiments, deposition of the first layer is performed in a first chamber and deposition of the elemental molybdenum layer is performed in a second chamber.

[0023] In various embodiments, the method also includes exposing the first layer to air prior to deposition of the elemental molybdenum layer.

[0024] In various embodiments, the elemental molybdenum layer is crystalline.

[0025] In various embodiments, the elemental molybdenum layer contains less than 1 atomic percent impurities.

[0026] In various embodiments, the elemental molybdenum layer is elemental molybdenum.

[0027] Another aspect is an apparatus for processing substrates, the apparatus including a first process chamber and a second process chamber each configured to accommodate a substrate, a substrate support in each of the first process chamber and the second process chamber, a gas inlet configured to direct gases into each of the first process chamber and the second process chamber via one or more showerheads, a heater configured to heat the substrate support in each process chamber, and a controller, the controller causing: (a) while the substrate is accommodated in the first process chamber, an oxygen-containing molybdenum precursor and a nitrogen-containing gas to be sequentially injected into the first process chamber; (b) after (a), the substrate is transferred to the second process chamber; and (c) after (b), the substrate is transferred to the second process chamber. (d) executing one or more program instructions selected from the group consisting of: injecting nitrogen into the first process chamber when the substrate is contained in the first process chamber; subjecting the temperature of the substrate support in the second process chamber to two different temperatures while the substrate is contained in the second process chamber; delivering a soak gas to the first process chamber before or after sequentially injecting the oxygen-containing molybdenum precursor and the nitrogen-containing gas into the first process chamber; and reducing the flow of hydrogen into the second process chamber while the substrate is contained in the second process chamber.

[0028] In various embodiments, at least one of the one or more showerheads is a single plenum showerhead.

[0029] In various embodiments, at least one of the one or more showerheads is a dual plenum showerhead.

[0030] In various embodiments, the process chamber is a chamber in a multi-chamber apparatus.

[0031] Another aspect includes an apparatus for processing a substrate, the apparatus including: a process chamber configured to accommodate a substrate; a substrate support within the process chamber; a first gas box including a gas source for accommodating hydrogen gas; a second gas box including a gas source for accommodating a molybdenum-containing gas; a third gas box including a gas source for accommodating a boron-containing gas or a tungsten-containing gas; a gas inlet configured to direct gas from each of the first gas box, the second gas box, and the third gas box into the process chamber through one or more showerheads; and a heater configured to heat the substrate support within each process chamber.

[0032] In various embodiments, at least one of the one or more showerheads is a single plenum showerhead.

[0033] In various embodiments, at least one of the one or more showerheads is a dual plenum showerhead.

[0034] In various embodiments, the process chamber is a chamber in a multi-chamber apparatus.

[0035] These and other aspects are described below with reference to the drawings. [Brief explanation of the drawings]

[0036] [Figure 1A] FIG. 1A is a schematic example of a material stack including a nucleation layer as a template for metal growth. [Figure 1B] FIG. 1B is a schematic example of a material stack including a nucleation layer as a template for metal growth.

[0037] [Figure 2A] FIG. 2A illustrates an example of a structure in which a material stack may be employed according to various embodiments. [Figure 2B]FIG. 2B illustrates an example of a structure in which a material stack may be employed according to various embodiments.

[0038] [Figure 3A] FIG. 3A is a process flow diagram illustrating operations in a method for depositing a conductive material, according to various embodiments. [Figure 3B] FIG. 3B is a process flow diagram illustrating operations in a method for depositing a conductive material, according to various embodiments. [Figure 3C] FIG. 3C is a process flow diagram illustrating operations in a method for depositing a conductive material, according to various embodiments.

[0039] [Figure 4] FIG. 4 is an example of a material stack with a graded composition in the nucleation layer, according to various embodiments.

[0040] [Figure 5] FIG. 5 is a schematic diagram of an exemplary process chamber for practicing the disclosed embodiments.

[0041] [Figure 6] FIG. 6 is a schematic diagram of an exemplary gas flow diagram for an apparatus that may be used to practice certain disclosed embodiments. [Figure 7A] FIG. 7A is a schematic diagram of an exemplary gas flow diagram for an apparatus that may be used to practice certain disclosed embodiments. [Figure 7B] FIG. 7B is a schematic diagram of an exemplary gas flow diagram for an apparatus that may be used to practice certain disclosed embodiments. [Figure 7C] FIG. 7C is a schematic diagram of an exemplary gas flow diagram for an apparatus that may be used to practice certain disclosed embodiments.

[0042] [Figure 8] FIG. 8 is a block diagram of a processing system suitable for performing deposition processes in accordance with embodiments described herein.

[0043] [Figure 9] FIG. 9 is a graph of the atomic content of various elements in stacks deposited in accordance with certain disclosed embodiments. Detailed Description of the Invention

[0044] In the following description, numerous specific details are set forth to provide a thorough understanding of each presented embodiment. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that no limitation of the disclosed embodiments is intended.

[0045] Semiconductor manufacturing processes involve the formation of 3D NAND devices. Metallization of the gate contact of 3D NAND transistors involves the deposition of highly conductive, low-resistivity metals, especially in small features. Tungsten (W) is used for the metallization of 3D NAND devices. Deposition of W for the gate contact involves the formation of a titanium nitride (TiN) liner layer, followed by a W nucleation layer, and finally a W bulk layer. The TiN layer serves as both a barrier layer and an adhesion layer to promote efficient nucleation of the W nucleation layer and to promote the formation of high-quality bulk W. Nucleation layers often contain boron from the boron-containing reactants used to deposit the nucleation layer, which has a higher resistivity than bulk W. Because numerous layers are deposited, less space is available for the deposition of high-quality, low-resistivity bulk W, especially as devices continue to shrink.

[0046] Molybdenum (Mo) metallization is an alternative metallization option. During Mo metallization, a liner layer is deposited, followed by a bulk Mo layer. During the deposition of the bulk Mo layer, process conditions can be controlled to convert the liner layer almost completely to elemental Mo, allowing more of the space within the feature to be filled with elemental Mo, which has a lower resistivity than the unconverted liner layer plus bulk Mo. Overall, this places elemental Mo in contact with the gate oxide.

[0047] One of the features of a 3D-NAND device is its ability to retain data within the device. One advantage of using a 3D-NAND device is its non-volatility. After data is written to the transistors in a 3D-NAND device, it can be left without power for a period of time. When the 3D-NAND device is subsequently powered on, the data is still written to the transistors, and it is expected to function as a valid 3D-NAND device. The ability of the transistors to retain that data after a period of time is sometimes referred to as data retention (e.g., whether data can be validly retained within the device).

[0048] Data retention in 3D-NAND devices using Mo as the gate metal for memory cell transistors was not as effective as W-based 3D-NAND devices where the liner layer was converted completely to elemental Mo. The overall resistivity of the stack can be lower, but data retention may not be as effective.

[0049] Without being bound by any particular theory, it is believed that oxygen and other non-molybdenum constituent elements (such as aluminum) are flaked off from the gate oxide stack during gate metal deposition, creating vacancy defects and increasing leakage of nonvolatile trapped charge. This leakage of trapped charge results in reduced data retention, meaning data is lost more quickly. Without being bound by any particular theory, it is believed that quantum tunneling caused by defects in the dielectric film within the gate oxide stack at the dielectric-metal interface contributes to increased data loss. For example, when a defect in the dielectric film is close to an electron, the electron can overcome an energy barrier and escape from the dielectric. The more defects there are in the dielectric film, the easier it is for electrons originally trapped in the dielectric trap layer to escape from the dielectric, resulting in faster data loss. It is believed that oxygen within the stack is removed from the stack, creating defects that allow quantum tunneling, thereby contributing to increased data loss.

[0050] One potential method for reducing the loss of oxygen and non-molybdenum elements is to provide an excess of oxygen and non-molybdenum elements in the initial gate metal film or to fabricate the metal-dielectric interface to have a composition similar to the TiN·W incorporation scheme used in the gate oxide stack. This may reduce the driving force for oxygen and other non-molybdenum elements to be lost from the gate oxide stack. It is also believed that retaining oxygen or other elements in a nucleation layer can prevent oxygen and other elements from being removed from the dielectric. For example, when a metal layer is deposited on a nucleation layer, the process conditions for depositing the metal layer are believed to cause interaction between the nucleation layer and the dielectric layer, removing oxygen from the dielectric layer. However, if oxygen or other non-molybdenum impurities are retained in the nucleation layer, the rate of data loss is significantly reduced.

[0051] The electrical characteristics of memory devices also changed with the change in wordline metal from W to Mo. Traditionally, tungsten integration required barrier metals such as TiN, tungsten nitride (WN), or tungsten carbonitride (WCN). Deposition of the TiN barrier layer involved exposure to various chemicals, such as ammonia (NH), chlorine (Cl), and hydrochloric acid (HCl), at high temperatures; however, the overall process scheme accommodated these exposures to prevent trace amounts of these elements from substantially harming the control gate or capacitor dielectric. Deposition of the tungsten layer exposed the control gate and capacitor dielectric to various chemicals, such as diborane (BH), silane (SiH), hydrogen (H), tungsten hexafluoride (WF), and fluorine (F), as well as reaction by-products including, but not limited to, hydrofluoric acid (HF), boron trifluoride (BF), and silicon tetrafluoride (SiF). However, process schemes have been developed such that these exposures do not substantially harm the control gate or capacitor dielectric.

[0052] Semiconductor manufacturing processes have historically considered the use of TiN barrier layers and / or the deposition of tungsten-containing films, particularly those deposited using WF6 and B2H6 gases. The barrier metal layer may be a TiN layer deposited using a nitrogen-containing reactant such as NH3, a titanium-containing reactant such as titanium tetrachloride (TiCl4), and H2. Such depositions can introduce trace amounts of fluorine, boron, and other non-molybdenum constituent elements into the device. Some devices may operate optimally with these trace amounts remaining in the device, even when the metallization involves the deposition of Mo rather than W. However, while some Mo depositions may include a barrier layer, some integration schemes may be integrated without a barrier layer.

[0053] Without being bound by any particular theory, it is believed that the presence of trace amounts of non-molybdenum constituent elements at the dielectric-metal interface of a metallization stack can contribute to improved device performance when Mo is the metal used for metallization. Mo deposition can involve exposure to NH3, H2, and HCl, but these gases are not necessarily inherently harmful to the dielectric, as the process scheme for W deposition also involved such exposure. However, Mo deposition also produces reactive by-products such as Mo-containing precursors, water (HO) and nitric oxide (NO), oxides and suboxides of Mo, and molybdenum oxynitride (MoO). x N y ), which also includes exposure to the gases used in Mo deposition. Process schemes for W deposition typically do not involve exposure to these gases used in Mo deposition. To mitigate the potential adverse effects of such exposure, compounds to which the dielectric is exposed during W deposition can be used to tailor the dielectric-Mo interface and improve the electrical performance of the Mo gate oxide stack.

[0054] Certain disclosed embodiments address these issues in a variety of applications, including, but not limited to, 3D NAND fabrication of wordlines with barrier metal, 3D NAND fabrication of wordlines without barrier metal, DRAM embedded wordlines with barrier metal, DRAM embedded wordlines without barrier metal, and metal-oxide-semiconductor capacitor (MOSCAP) devices.

[0055] Although a dielectric-Mo interface is described herein as an example, it will be understood that the various disclosed embodiments are also suitable for preparing other dielectric-metal interfaces, including, but not limited to, aluminum oxide-molybdenum (Al2O3-Mo) interfaces, silicon oxide-molybdenum (SiO2-Mo) interfaces, zirconium oxide-molybdenum (ZrO2-Mo) interfaces, and other control gate dielectrics interfacing with metals such as Mo.

[0056] Provided herein are methods for forming Mo metallization stacks incorporating trace amounts of non-molybdenum constituent elements during the formation of the metallization stack. Such methods are particularly directed to modifying the dielectric-metal interface. The methods may be performed during any metal deposition operation, including, but not limited to, before deposition of any metal, before deposition of a metal nucleation layer such as a metal oxynitride, after deposition of some metals (including metal oxynitrides and bulk metals), after deposition of some of the metal nucleation layer, after deposition of the entire metal nucleation layer and before deposition of the bulk metal, throughout or during deposition of the metal nucleation layer, throughout or during deposition of the bulk metal, or after deposition of the bulk metal. When embodiments include a substrate having a barrier layer on a dielectric, the methods described herein may be performed on the dielectric before deposition of the barrier layer, after deposition of the barrier layer, or during deposition of the barrier layer. The methods described herein may incorporate one or more elements of oxygen, nitrogen, fluorine, boron, chlorine, and tungsten. In various embodiments, three-dimensional NAND gate transistors are fabricated using specific disclosed embodiments. Various disclosed embodiments involve plasma-free or plasma-less deposition. Various disclosed embodiments are thermal processes.

[0057] Certain disclosed embodiments maintain impurity contents of boron, fluorine, oxygen, nitrogen, chlorine, and other non-molybdenum constituent elements that may range from less than about 1 atomic % to about 50 atomic % per element type. In various embodiments, a graded composition may be formed in which the impurity content near the dielectric-metal interface is higher than in the bulk metal. The high impurity content may be from less than about 1 atomic % to about 50 atomic % in a range of less than about 1 Å to 30 Å of the Mo-containing material at the dielectric-Mo interface.

[0058] In some embodiments, the method includes one or more of the following operations: temperature and / or gas processing of a substrate (including a dielectric, a partial or full barrier layer, a partial or full metal nucleation layer, or a partial or full metal layer) with specific gases; and deposition in which at least one of the initial Mo layer deposition, processing of the interface between the liner layer and the bulk Mo layer, and deposition of the bulk Mo layer is modified to increase or preserve the content of oxygen and other elements in the liner layer. For example, deposition of the liner layer may include weakly reacting a Mo precursor to preserve oxygen in the metal film. The methods described herein are particularly advantageous for implementation in a multi-station apparatus for manufacturing semiconductor devices, such as a quad-station module available from Lam Research Corporation of Fremont, California. A quad-station module includes four stations, and at least one station may be used for molybdenum deposition according to certain disclosed embodiments. In one example, one station can be for liner deposition, another for optional starter layer deposition, yet another for bulk deposition, and yet another for overburden deposition to ensure complete feature fill. In some embodiments, a quad-station module allows liner deposition and bulk deposition to occur in two separate stations. Stations for liner and / or bulk deposition can be adjusted to lower deposition temperatures (or adjust or implement any other process conditions described herein for a particular disclosed embodiment), while other stations deposit at higher deposition temperatures or other process conditions that improve reaction rates, allowing for higher module throughput.

[0059] 1A and 1B are schematic examples of material stacks including a nucleation layer as a template for metal growth. FIGS. 1A and 1B illustrate the order of materials in a particular stack and may be used with any suitable architecture and application, as described below with respect to FIGS. 3 and 4. In the example of FIG. 1A, stack 100 includes substrate 102, which may be a silicon or other semiconductor wafer (e.g., a 200 mm, 300 mm, or 450 mm wafer) having one or more layers of material (such as a dielectric, conductive, or semiconductive material) deposited thereon. The method may also be applied to form metallization stack structures on other substrates, such as glass and plastic. In some embodiments, substrate 102 includes silicon.

[0060] The dielectric layer 104 is on the substrate 102. The dielectric layer 104 may be deposited directly on the semiconductor surface of the substrate 102, or any number of intervening layers may be present. Examples of dielectric layers include layers of doped and undoped silicon oxide (SiO), doped and undoped silicon carbide (SiC), silicon nitride (SiN), and aluminum oxide (AlO), with specific examples including doped or undoped layers of silicon oxide (SiO) and AlO. In another embodiment, as shown in FIG. 1B, the stack 100 includes a barrier layer 106 deposited between the nucleation layer 108 and the dielectric layer 104. The barrier layer 106 may be a diffusion barrier, an adhesion barrier, or both. Examples of barrier layers include TiN, Ti / TiN, WN, and WCN. In various embodiments, the thickness of the barrier layer 106 is between about 10 Å and about 40 Å, or between about 10 Å and about 20 Å. In FIG. 1A, a nucleation layer 108 is deposited on the dielectric layer 104, and a metal layer 110 is deposited on the nucleation layer 108. In FIG. 1B, the nucleation layer 108 is deposited on the barrier layer 106, and a metal layer 110 is deposited on the nucleation layer 108. FIGS. 1A and 1B show the dielectric-metal interfaces, i.e., 112a and 112b. Certain disclosed embodiments may include performing a processing operation before depositing the nucleation layer 108, performing a processing operation after depositing at least a portion of the nucleation layer 108, performing a processing operation after depositing all of the nucleation layer 108, adjusting deposition conditions for the nucleation layer 108, performing a processing operation before depositing the metal layer 110, performing processing during deposition of the metal layer 110, adjusting deposition conditions when depositing at least a portion of the metal layer 110, adjusting deposition conditions when depositing all of the metal layer 110, or combinations thereof. A metal layer 110 can be formed to contact the nucleation layer 108 at a dielectric-metal interface 112 .

[0061] The metal layer 110 deposited on the nucleation layer 108 is the main conductor (also called the bulk conductor or bulk layer) of the structure, with the nucleation layer 108 providing a template for metal growth.

[0062] As described below, the nucleation layer 108 may be deposited as an amorphous film. Because an amorphous film does not have a grain structure, it can serve as a template for metal growth, forming a low resistivity metal that does not have a grain structure and / or large grains (as opposed to small grains). An example of a metal layer is a Mo layer.

[0063] In the example of FIGS. 1A and 1B, the deposited nucleation layer 108 is MoO x N y The metal oxynitride layer may be a metal oxynitride layer, such as a metal oxynitride layer.

[0064] In certain disclosed embodiments, during subsequent processing, in certain embodiments, portions of the nucleation layer 108 are converted to pure metal, while portions of the nucleation layer 108, such as the region at the interface between the nucleation layer 108 and the dielectric layer 104, may retain impurities of non-molybdenum constituent elements, such as boron, fluorine, tungsten, oxygen, nitrogen, chlorine, etc., and portions of the nucleation layer 108 may not be converted to pure metal. Pure metal may be defined as having less than about 1% non-molybdenum constituent elements.

[0065] Non-molybdenum elemental impurities can be intentionally maintained in the nucleation layer 108 at or near the dielectric-metal interface to reduce the chance of oxide diffusion from the dielectric, which can cause data loss. Thus, according to various embodiments, the nucleation layer 108 may or may not have the same composition as the metal layer 110. In some embodiments, the nucleation layer 108 includes multiple layers, is a graded film, or is a single layer deposited by repeating at least one ALD cycle using the same precursor and reactant flows in each cycle. When depositing the metal layer 110, the nucleation layer 108 is modified, resulting in a gradient, multiple layers, a change in morphology, or a change in the impurity composition of the nucleation layer. In some embodiments, one or more of the multiple layers is a graded film. In some embodiments, the nucleation layer 108 is characterized by amorphousness, and the metal layer 110 is characterized by the absence of grain boundaries.

[0066] In some embodiments, the metal of the metal oxynitride layer is the same as the metal of the pure metal conductor, e.g., MoO x N y The layer may be deposited as a nucleation layer prior to the deposition of the Mo layer. In other embodiments, the metal oxynitride layer may have a metal different from that of the pure conductor, for example, a W layer may be deposited on a Mo-containing nucleation layer, or a Mo layer may be deposited on a W-containing nucleation layer.

[0067] 1A and 1B show examples of metallization stacks, the methods and resulting stacks are not so limited. For example, in some embodiments, a nucleation layer may be deposited directly on SiO2, silicon, or other semiconductor substrates as a template for metal growth. Furthermore, while the growth of W or Mo on a nucleation layer is described above, the nucleation layer may also serve as a template for the low-resistivity growth of other metals, such as cobalt (Co), ruthenium (Ru), nickel (Ni), and alloys containing these metals, such as MoW. Additionally, the nucleation layer may be formed of MoO x N y , Mo nitride, tungsten oxynitride, WN, nickel nitride, etc., may be a suitable metal oxynitride or metal nitride layer.

[0068] The material stacks described above and further below may be implemented in a variety of structures. FIGS. 2A and 2B illustrate examples of structures in which the stacks may be employed. FIG. 2A illustrates a schematic example of word lines 210 of a two-dimensional NAND structure 223. The word lines 210 are separated by oxide layers 211 as pillars with gaps 235 on a substrate 200. FIG. 2B illustrates a detail of the interface between the word lines 210 and the oxide layer 211, including an Al2O3 layer 204 and a nucleation layer 208. In some embodiments, the nucleation layer 208 may be deposited directly on the oxide layer 211 or on a TiN 204 or other barrier layer described herein. The nucleation layer may be, for example, between about 10 Å and 100 Å, or between 10 Å and 50 Å, for deposition of word lines 210 between about 10 nm and 100 nm thick, or about 5 nm thick or less.

[0069] FIG. 3A is a process flow diagram illustrating operations in a method for depositing a conductive material according to certain disclosed embodiments. In operation 301, a substrate having an oxide surface and / or a barrier layer surface (which may be on an oxide surface) is provided. Example process conditions and features of operation 301 are described below with respect to FIG. 3B. In operation 360, the oxide-metal interface is prepared to prevent oxide defects. Exemplary methods for performing operation 360 are described below with respect to FIGS. 3B and 3C. In operation 370, a metal layer is formed over the substrate, thereby contacting the metal with the oxide or barrier layer surface. Exemplary embodiments for performing operation 370 are described below with respect to FIGS. 3B and 3C.

[0070] 3A, operations 360 and 370 may be performed simultaneously, operation 360 may be performed first followed by operation 370, operation 370 may be performed first followed by operation 360, a combination of operations 360 and 370 may be performed together (e.g., alternating), some operations of operation 360 may be performed between operations 370, or some operations of operation 370 may be performed between operations 360. Operations 301, 360, and 370 may each be performed in the same chamber, a single chamber, one or more stations in the same chamber, or one or more stations in separate chambers.

[0071] Figure 3B is a process flow diagram illustrating operations in a method for depositing a conductive material. It will be understood that operations 301, 303a, 305, 307, and 309 may each be performed in the same chamber as one of the other operations in Figure 3B, in a separate chamber, or using a combination of the same chamber and separate chambers, and that operations 301, 303a, 305, 307, and 309 may each be performed in the same station within the same multi-station chamber as one of the other operations in Figure 3B, in a separate station, or using a combination of the same station and separate stations.

[0072] At least one of the operations marked as optional in Figure 3B is performed. Each optional operation may be used in combination with other optional operations in Figure 3B. For example, processing in operation 303a may be performed without adjusting the process conditions in operations 305 and 309 and without processing in operation 307.

[0073] In operation 301, a substrate having an oxide surface is provided. This may be the same as operation 301 in FIG. 3A. In various embodiments, the substrate has a dielectric layer including an oxide surface thereon. In various embodiments, the substrate is provided in a first process station of a multi-station chamber. The substrate may be a silicon wafer (e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer), including wafers having one or more layers of material (such as dielectric, conductive, or semiconductive materials) deposited thereon. Non-limiting examples of underlayers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers. In some embodiments, the substrate is the same as substrate 102 in FIG. 1A or 1B.

[0074] The substrate comprises an oxide surface. In some embodiments, the oxide surface is part of a dielectric layer, such as dielectric layer 104 in FIG. 1A. In some embodiments, the oxide surface is part of a barrier layer, such as barrier layer 106 in FIG. 1B. In some embodiments, the oxide surface comprises silicon oxide. In some embodiments, the oxide surface comprises aluminum oxide.

[0075] 3, in operation 303a, an optional soaking process is performed. The optional soaking process may be performed to prepare an oxide surface on the substrate prior to operation 305. The soaking may result in the deposition of material in operation 305 being deposited in a different manner or may result in a different composition on the oxide surface.

[0076] In various embodiments, operation 303a involves the introduction of a boron-containing gas, such as diborane (B2H6). Exposure to the boron-containing gas can make the dielectric process history more similar to previous process histories involving TiN incorporating tungsten.

[0077] In various embodiments, operation 303a involves the introduction of a tungsten- or fluorine-containing gas, such as a tungsten halide, including, but not limited to, tungsten hexachloride, tungsten pentachloride, tungsten pentafluoride, and tungsten hexafluoride (WF). Fluorine exposure can make the dielectric process history more similar to that of tungsten-incorporated TiN. However, exposure may be limited to avoid exposing the dielectric to too much fluorine, which could adversely affect device performance, although trace exposure may be advantageous for matching the device performance of W-incorporated TiN.

[0078] In various embodiments, operation 303a is performed with two or more time-separated pulses of gas processing. For example, in some embodiments, the exposure may be alternating between B2H6 and WF6, as is done when depositing a W nucleation layer by atomic layer deposition. This operation may be performed to more closely resemble the dielectric process history of W-incorporated TiN. The W nucleation layer that may be deposited by performing operation 303a is minimized (e.g., very few cycles, such as 1-5 or 1-10 cycles, are used) to avoid negatively affecting the resistivity of Mo or a subsequent metal conductor layer. In various embodiments, an ultrathin W nucleation layer deposited by ALD prior to Mo deposition may reduce Mo resistivity by providing a template for large-grain or amorphous Mo growth. In various embodiments, the boron-containing gas and W-containing or fluorine-containing gas exposures are performed simultaneously, as in a chemical vapor deposition (CVD)-based process. A combination of ALD and CVD processes may also be used.

[0079] Operation 303a may be performed as a separate operation before operation 305, or may be performed during operation 305, such as after several nucleation layers have been deposited, such that operations 303a and 305 may be performed in a time-alternating operation. In some embodiments, operation 303a is performed cyclically throughout the other operations performed in FIG. 3.

[0080] In some embodiments, the soaking process involves exposing the oxide surface to one or more gases, such as an oxygen-containing gas, a nitrogen-containing gas, or other suitable gases capable of altering the interface between the oxide surface and the subsequently deposited material and reducing oxide-to-oxide electron tunneling within the substrate, and combinations thereof. Examples of oxygen-containing gases include oxygen gas. Examples of nitrogen-containing gases include NH3 gas and nitrogen.

[0081] Operation 303a may be performed at any suitable temperature, non-limiting examples of which include up to about 650° C., or less than about 350° C., or from about 250° C. to about 350° C. Non-limiting examples of chamber pressures include up to about 90 Torr, or from about 5 Torr to about 50 Torr, or from about 5 Torr to about 15 Torr, or about 10 Torr.

[0082] The exposure time may vary depending on the flow rate. Non-limiting examples of exposure times range from about 0.1 seconds to about 10 seconds, or from about 0.1 seconds to about 20 seconds, for each gas. For alternating processing pulses, each pulse may have any of the above exposure times. The overall duration of operation 303a may range from about 0.1 seconds to about 20 seconds, or from about 0.1 seconds to about 15 seconds, or from about 0.1 seconds to about 10 seconds.

[0083] The exposure time of the B2H6 and hydrogen gas may be between about 0.1 seconds and about 10 seconds. For example, in some embodiments, B2H6 and hydrogen may be simultaneously flowed over the substrate for about 0.1 seconds to about 10 seconds.

[0084] The exposure time of the WF6 gas may be between about 0.1 seconds and about 1 second. For example, in some embodiments, WF6 may be flowed over the substrate for about 0.1 seconds to about 1 second.

[0085] When alternating pulses are performed, a purge operation may be performed between the alternating pulses. The purge may include flowing argon gas or other inert gas for a specified duration, such as between about 0.1 seconds and about 1 second.

[0086] In one example embodiment in which alternating pulses are performed in operation 303a, one cycle of pulses may include: (1) dispensing B2H6 and hydrogen for 0.1 seconds to 10 seconds; (2) purging with argon gas for 0.1 seconds to 1 second; (3) dispensing WF6 between 0.1 seconds and 1 second; and (4) purging with argon gas for 0.1 seconds to 1 second.

[0087] The flow rate of the gas(es) depends on the chemistry of the gas(es) selected, the oxide surface material, the duration of exposure, the mixture of gases if multiple gases are flowed, and the desired soaking effect for a given substrate. The duration of gas exposure depends on the gas flow rate, the type of gas, and the desired soaking effect.

[0088] Non-limiting examples of gas flow rates for flowing oxygen gas vary from about 100 sccm to about 10,000 sccm. Example durations of oxygen gas flow include between about 0.1 seconds and about 30 seconds.

[0089] Non-limiting examples of gas flow rates for flowing NH3 gas vary from about 100 sccm to about 10,0000 sccm. Example durations of NH3 gas flow include between about 0.1 seconds and about 30 seconds.

[0090] Non-limiting example gas flow rates for flowing nitrogen gas vary from about 100 sccm to about 10,000 sccm. Example durations for flowing nitrogen gas include from about 0.1 seconds to about 30 seconds.

[0091] In operation 305, a conformal nucleation layer is formed on the substrate by atomic layer deposition (ALD). In various embodiments, the conformal nucleation layer is deposited on the oxide surface of the substrate provided in operation 301. In some embodiments, operation 303a and operation 305 are performed in the same chamber, in separate chambers in the same tool, or without breaking vacuum. In some embodiments, an air break occurs after operation 303a and before operation 305, which is advantageous because exposed boron or fluorine atoms may be present on the surface after operation 303a and these atoms may oxidize and incorporate oxygen into the device before operation 305, thereby reducing the likelihood of oxide loss or diffusion of incorporated non-molybdenum constituent elements, thereby reducing the resistivity of the overall film stack and / or reducing data loss.

[0092] During operation 305, process conditions may be adjusted to modify the composition of the conformal nucleation layer. For example, process conditions may be adjusted to increase the non-molybdenum constituent element content of the conformal nucleation layer, such as the oxygen, chlorine, and / or nitrogen content. It will be understood that in some embodiments, process conditions may not be adjusted in operation 305 if an optional soak process is performed in operations 303a or 307 and / or if process conditions are adjusted in operation 309. Similarly, process conditions may be adjusted in operation 305 while also performing at least one of the soak processes of operations 303a and 307, and process conditions may be adjusted in operation 309, or any combination herein.

[0093] In an ALD process, the substrate may be cycled by first exposing the substrate to a pulse of an appropriate metal-containing precursor, optionally purging the precursor, then exposing the substrate to a pulse of a reducing agent, and then optionally purging the reducing agent, until a nucleation layer of the desired thickness is formed on the substrate. It will be appreciated that the order of precursor and reducing agent may be reversed, with the sequence beginning with the administration of the reducing agent followed by the administration of the metal-containing precursor. Purging may be performed by flowing an inert gas, such as argon. In some embodiments, the inert gas may also be used as a carrier gas to deliver one or more gases, including, but not limited to, a soak gas, a precursor gas, and a reactant gas, to the substrate.

[0094] ALD is a technique for depositing thin layers of materials using a sequence of self-limiting reactions. Typically, an ALD cycle involves delivering at least one reactant to a substrate surface, allowing it to adsorb, and then reacting the adsorbed reactant with one or more other reactants to form a partial layer of the film. As an example, MoO x N yA deposition cycle may include the following operations: (i) delivery / adsorption of a Mo-containing precursor; (ii) purging the Mo precursor from the chamber; (iii) delivery of a nitrogen-containing reactant or nitrogen-containing gas; and (iv) purging the nitrogen-containing reactant from the chamber.

[0095] Unlike chemical vapor deposition (CVD) techniques, ALD processes deposit films layer by layer using a surface-mediated deposition reaction. In one example of an ALD process, a substrate surface containing a population of surface-active sites is exposed to a gas-phase distribution of a dose of a first precursor (e.g., a Mo-containing precursor) provided to a chamber housing the substrate. Molecules of this first precursor are adsorbed onto the substrate surface, including chemisorbed and / or physisorbed molecules of the first precursor. As described herein, it should be understood that when a compound is adsorbed onto a substrate surface, the adsorbed layer may include derivatives of the compound in addition to the compound. For example, an adsorbed layer of a Mo-containing precursor may include derivatives of the Mo-containing precursor in addition to the Mo-containing precursor. After the first precursor is dispensed, the chamber is evacuated to remove most or all of the first precursor remaining in the gas phase, leaving most or only the adsorbed species. In some implementations, the chamber need not be completely evacuated. For example, the chamber may be evacuated so that the partial pressure of the first precursor in the gas phase is low enough to mitigate reaction. A second reactant, such as a nitrogen-containing reactant, is introduced into the chamber, and some of these molecules react with the first precursor adsorbed on the surface. In some processes, the second reactant reacts immediately with the adsorbed first precursor. The chamber may then be evacuated again to remove unbound second reactant molecules. As noted above, in some embodiments, the chamber may not be fully evacuated. Additional ALD cycles may be used to increase the film thickness.

[0096] In certain embodiments, the administration of the first precursor in an ALD process partially saturates the substrate surface. In some embodiments, the administration phase of an ALD cycle is terminated before the precursor contacts the substrate and uniformly saturates the surface. Typically, at this point, the precursor flow is stopped or diverted, and only the purge gas flows. By operating in this subsaturation regime, the ALD process reduces cycle time and increases throughput. However, because precursor adsorption is not limited to saturation, the concentration of adsorbed precursor may vary slightly across the substrate surface. An example of ALD process operation in the subsaturation regime is provided in U.S. Patent Application No. 14 / 061,587 (now U.S. Patent No. 9,355,839), filed October 23, 2013, entitled "Subsaturated Atomic Layer Deposition and Conformal Film Deposition," which is incorporated herein by reference in its entirety. While ALD is described herein as an example, it will be understood that films deposited by ALD herein may be deposited by CVD or other techniques.

[0097] The substrate temperature for nucleation layer deposition may range, for example, from 250°C to about 600°C, or from 300°C to 600°C, or from 250°C to about 550°C. In some embodiments, lower temperatures may be used. Such temperatures may be less than 500°C, less than 550°C, less than 450°C, less than 400°C, or less than 350°C. Low temperatures may be used to improve step coverage. Furthermore, low temperatures may increase the amount of impurities in the nucleation layer, increasing amorphousness and resulting in larger grain sizes in the subsequently deposited conductor. In various embodiments, it may be advantageous to deposit the nucleation layer at low temperatures. The chamber pressure may be between about 5 Torr and about 90 Torr, between about 5 Torr and about 50 Torr, between about 20 Torr and about 40 Torr, or about 30 Torr.

[0098] The surface on which the nucleation layer is deposited depends on the particular application. In some embodiments, the nucleation layer is deposited directly on a dielectric (e.g., silicon oxide, aluminum oxide, silicon nitride, etc.) surface. In some embodiments, the nucleation layer is deposited on a barrier layer. In some embodiments, the nucleation layer is deposited before depositing any other metal on the surface. In some embodiments, the nucleation layer is deposited on a processed dielectric. In some embodiments, the nucleation layer is deposited on a tungsten nucleation layer. In some embodiments, the nucleation layer is deposited on a raw dielectric. In some embodiments, the nucleation layer is deposited on a processed barrier layer. In some embodiments, the nucleation layer is deposited on a raw barrier layer. In some embodiments, the nucleation layer is deposited directly on TiN or other surfaces. In some embodiments, subsequent elemental metal deposition may be performed on any surface.

[0099] In various embodiments, the ALD process in operation 305 involves flowing an oxygen-containing Mo precursor and a reducing agent in successive alternating pulses or doses. In some embodiments, the reducing agent is ammonia (NH) or other nitrogen-containing gas, or a nitrogen-containing reducing agent such as hydrazine (NH). Ammonia chemisorption to the dielectric is preferable to hydrogen (H) chemisorption to the nucleation layer. In some embodiments, the reducing agent and precursor are selected so that the reducing agent reacts without dissociating. Ammonia reacts with metal oxychlorides and metal chlorides without dissociating. This is in contrast to ALD from metal oxychlorides, for example, which uses hydrogen as the reducing agent. Hydrogen dissociates at the surface to form adsorbed atomic hydrogen, resulting in very low concentrations of reactive species and low surface coverage during the initial nucleation of the metal on the dielectric surface. The use of NH and metal oxychloride or metal chloride precursors reduces or eliminates nucleation delay at deposition temperatures up to several hundred degrees lower than those used in hydrogen reduction of the same metal precursor.

[0100] In some embodiments, the reducing agent may be a boron- or silicon-containing reducing agent, such as B2H6 or SiH4. These reducing agents may be used with metal chloride precursors and metal oxychlorides. However, B2H6 and SiH4 react with water, which is formed as a by-product during the ALD process, to form solids, B2O3 and SiO2, which are insulating and remain in the film, increasing resistivity. The use of NH3 also provides better adhesion than B2H6 and SiH4 ALD processes on certain surfaces, including Al2O3.

[0101] Examples of metal oxychlorides and metal chloride precursors include molybdenum oxychlorides such as molybdenum pentachloride (MoCl5), dioxymolybdenum dichloride (MoO2Cl2), and molybdenum oxytetrachloride (MoOCl4), tungsten oxychlorides (WO3), such as tungsten pentachloride (WCl5), tungsten hexachloride (WCl6), tungsten tetrachloride (WCl4), tungsten dichloride (WCl2), and tungsten oxytetrachloride (WOCl4). x Cl y ) are mentioned.

[0102] Metal chlorides and metal oxychlorides can be useful in embodiments where fluorine incorporation is a concern. However, in some embodiments, fluorine-containing precursors such as nitrogen trifluoride (NF3) may be used. These include metal fluorides such as WF6, molybdenum hexafluoride (MoF6), and molybdenum pentafluoride (MoF5).

[0103] The resulting nucleation layer is generally not a pure elemental film, but rather a metal nitride or metal oxynitride film. In some embodiments, residual chlorine or fluorine from the deposition may be present, especially if the deposition is performed at low temperatures. In some embodiments, only trace amounts of residual chlorine or fluorine are present. In some embodiments, the nucleation layer is amorphous. Impurities in the film (e.g., oxygen, NH3, chlorine, or other halogens) promote the growth of an amorphous microstructure. In some embodiments, the deposited nucleation layer is an amorphous metal oxynitride layer or an amorphous metal nitride layer. The amorphous nature serves as a template for the growth of large grains in the subsequently deposited conductor. The surface energy of nitrides or oxynitrides relative to oxide surfaces is much more favorable than the surface energy of metals on oxide surfaces, facilitating the formation of continuous, smooth films on dielectrics. This allows for the formation of thin, continuous layers. Exemplary thicknesses of the nucleation layer range from 5 Å to 30 Å upon deposition. Depending on the temperature, this may be, for example, 5 to 50 ALD cycles.

[0104] During operation 305, deposition process conditions are optionally adjusted to increase or adjust the amount of non-molybdenum constituent elements or "impurities" in the film. One technique is to vary the exposure time and / or exposure flow during the deposition process. For example, in an ALD process, the substrate is first exposed to a pulse of an appropriate metal-containing precursor, followed by a pulse of a reducing agent. In various embodiments, the flow of the reducing agent is modified to retain more of the impurities from the metal-containing precursor in the resulting metal oxynitride film. Example flow rates for the reducing agent include about 100 sccm to about 40,000 sccm. The flow rate is used during the reducing agent pulse.

[0105] In some embodiments, one or more additive gases are flowed during at least one of the exposure to the precursor and the exposure to the reducing agent. The additive gas may include an oxygen-containing gas, a nitrogen-containing gas, or a combination thereof. An example of an oxygen-containing gas is oxygen. An example of a nitrogen-containing gas is nitrogen and NH3. The additive gas may be flowed continuously, together with the Mo precursor only, together with the reducing agent only, together with the purge gas only, or periodically without synchronization with any of the precursor dosage, reducing agent dosage, or purge gas operation.

[0106] Another technique that can be performed alone or in combination with the above techniques is to modify the process conditions. For example, the temperature or pressure can be adjusted to retain oxygen, nitrogen, and other constituent elements in the metal oxynitride layer. In various embodiments, operation 305 can be performed at temperatures up to about 650°C, or less than about 350°C, or between about 200°C and about 550°C, or between about 250°C and about 350°C to retain impurities in the film. In some embodiments, the chamber pressure can be between about 5 and about 90°C.

[0107] Another technique for preserving impurity content in the nucleation layer is to alter the film morphology. Amorphous films reduce the diffusion of impurities from the film, thereby reducing the chance of oxygen or other elements diffusing out of the dielectric, thereby reducing the chance of trapped charges escaping the dielectric and causing data loss. Morphology may be adjusted by reducing the substrate temperature during film deposition and bulk molybdenum deposition.

[0108] While certain disclosed embodiments may include conditioning the first few cycles of ALD in operation 305, some embodiments may condition most or all of the ALD cycles in operation 305. Any combination of conditioned ALD cycles may be performed to improve throughput, including alternating conditioned and unconditioned cycles, such as several cycles of low-temperature ALD followed by several cycles of high-temperature ALD, repeating sequentially.

[0109] The exposure time of the gases used to deposit the nucleation layer can vary depending on the flow rate. Non-limiting examples of exposure times range from about 0.1 seconds to about 10 seconds, or from about 0.1 seconds to about 20 seconds, for each gas. In alternating processing pulses, each pulse can have any of the above exposure times.

[0110] The exposure time of the NH3 and hydrogen gas depends on the particular application and can range widely. In some embodiments, the hydrogen gas exposure can be at least about 30 seconds or more. Non-limiting examples of exposure times include between about 0.1 seconds and about 60 seconds, between about 0.1 seconds and about 50 seconds, and at least about 30 seconds. For example, in some embodiments, NH3 and hydrogen can be flowed simultaneously to the substrate for at least about 30 seconds, or between about 0.1 seconds and about 50 seconds.

[0111] Oxygen-containing Mo precursor (formula MoO x Cl y For example, in some embodiments, an oxygen-containing Mo precursor may be flowed to the substrate for about 0.1 seconds to about 10 seconds.

[0112] If alternating pulses are performed, a purge operation may be performed between the alternating pulses. The purge may include flowing argon gas or other inert gas for a specified duration, such as between about 0.1 seconds and about 5 seconds.

[0113] In one example embodiment where alternating pulses are performed in operation 305, one cycle of pulses may include: (1) administering NH3 and hydrogen for 0.1 to 10 seconds; (2) purging with argon gas for 0.1 to 5 seconds; and (3) MoO. x Cl y for 0.1 seconds to 10 seconds; and (4) purging with argon gas for 0.1 seconds to 5 seconds.

[0114] 3B, a soak is optionally performed in operation 307. In some embodiments, this soak is performed in addition to or instead of operation 303, without adjusting process conditions in operation 305, or with adjusting process conditions in operation 305. In various embodiments, the soak performed can use any one or more of the techniques described above with respect to operation 303a.

[0115] Operation 307 may be performed as a separate operation after operation 305, or may be performed during operation 305, such as after several nucleation layers have been deposited, so that operations 307 and 305 are performed in a temporally alternating operation. In some embodiments, operation 307 is performed cyclically throughout the other operations performed in Figure 3B. Operation 307 may be performed after several main conductor layer materials have been deposited in operation 309, or may be performed before any main conductor layer materials are deposited in operation 309.

[0116] In operation 309, a main conductor layer is formed. In various embodiments, the main conductor layer is formed by ALD while adjusting process conditions. In various embodiments, deposition is performed over, on, or directly on a nucleation layer. The main conductor layer may be referred to as a bulk layer or a metal layer. In various embodiments, the main conductor layer is a Mo layer. In various embodiments, the main conductor layer is an elemental Mo layer. In various embodiments, the amount of impurities in the main conductor layer is less than about 1%.

[0117] The main conductor layer is deposited by ALD using alternating pulses of an oxygen-containing metal precursor (such as a metal oxyhalide) and a reducing agent. In some embodiments, the main conductor layer is deposited by ALD using an oxygen-containing Mo precursor and hydrogen as the reducing agent. In some embodiments, a purge gas may be used, and any of the purge gases described above with respect to operation 305 may be used in operation 309.

[0118] Operation 309 may use any of the Mo precursors described above with respect to operation 305. The Mo precursor may be a molybdenum oxyhalide. In some embodiments, the molybdenum oxyhalide is molybdenum oxychloride (MoO x Cl y Examples of metal oxychlorides and metal chloride precursors that can be employed in operations 305 and 309 include molybdenum oxychlorides such as molybdenum pentachloride (MoCl5) and molybdenum hexachloride (MoCl6), molybdenum dioxide dichloride (MoOCl2) and molybdenum oxytetrachloride (MoOCl4), tungsten oxychlorides (WOCl5), tungsten hexachloride (WCl6), tungsten tetrachloride (WCl4), tungsten dichloride (WCl2), tungsten oxytetrachloride (WOCl4), and the like. x Cl y ) are mentioned.

[0119] Without being bound by any particular theory, it is believed that impurities are removed from the nucleation layer during deposition of the main conductor layer. In embodiments in which the nucleation layer is deposited using oxygen- and chlorine-containing metal precursors and nitrogen-containing reactants, the impurities present may include oxygen, chlorine, and nitrogen. It is believed that chlorine tends to be removed first from the nucleation layer during deposition of the main conductor layer, such as when higher temperatures are used for deposition. Chlorine may be removed followed by oxygen and / or nitrogen. Without being bound by any particular theory, it is believed that slowing the rate of deposition of the main conductor layer reduces the amount of impurities that leave the nucleation layer.

[0120] Adjusting the process conditions in operation 309 helps preserve the impurity content of the nucleation layer deposited in operation 307 so that the nucleation layer is not completely or predominantly converted to metal during operation 309. Operation 309 is performed after operation 309 under process conditions such that the resulting nucleation layer composition after operation 309 has a metal to impurity atomic ratio of between about 100:1 and about 1:4, or a Mo to oxygen atomic ratio of between about 100:1 and about 1:4.

[0121] Adjusting the process conditions may be performed in various ways. One method is to perform two or more different sets of ALD cycles and keep the composition of the conductor layer unchanged during the first few deposition cycles, thereby preserving the impurities introduced during the deposition of the nucleation layer in operation 307. The first few cycles may refer to the first through tenth or first through twentieth ALD cycles in operation 309. The first few cycles refer to cycles sufficient to deposit up to 30% of the feature with the main conductor layer material. Conditions during these first few cycles may be adjusted to prevent impurities from escaping the nucleation layer. During the first set of ALD cycles, deposition is performed at a lower temperature to reduce the amount of impurities removed from the nucleation layer. Exemplary temperatures may be less than 500°C, less than 550°C, less than 450°C, less than 400°C, or less than 350°C. Lower temperatures may be used to reduce the amount of nucleation layer converted to an elemental film so that the amount of impurities or non-molybdenum constituent elements in the nucleation layer is maintained or is greater than about 1%, or at least greater than 0%. In this operation, the reducing agent may be hydrogen (H). The temperature may be the same as that used in operation 305 in some embodiments. The metal precursor may also be the same precursor employed in operation 305 or a different precursor. In some embodiments, the same precursor is used, and only the reducing agent is changed. According to various embodiments, operation 309 may or may not deposit a significant amount of a film of the main conductor. After the first few cycles, subsequent sets of ALD cycles may be performed at higher temperatures, such as between about 350°C and about 700°C. Higher temperatures can increase the deposition rate of the main conductor layer, particularly Mo, because some Mo precursors can be more efficient and reactive at higher temperatures.

[0122] Another technique is to adjust the flow of precursor and reducing agent to vary the rate of deposition of the main conductor layer. The precursor flow can be increased relative to the reducing agent flow so that there is insufficient reducing agent to convert the adsorbed precursor, or the reducing agent flow can be decreased while the precursor flow is held constant so that there is insufficient reducing agent to convert the adsorbed precursor to metal. When the precursor flow is increased, an example ratio of the precursor flow to the reducing agent flow can be between about 1:1000 and about 1:10,000. When the hydrogen reducing agent flow is decreased, an example ratio of the reducing agent flow to the precursor flow can be between about 1:10 and about 1:1000.

[0123] In some embodiments, graded films may be formed using certain disclosed embodiments, such that the metal-containing film has higher impurity levels near the dielectric or barrier layer, while the metal-containing film has lower impurity levels with increasing distance from the dielectric layer, resulting in fewer or no impurities in the last few cycles of metal deposited on the main conductor layer. Graded films may be deposited by using various different sets of ALD cycles during deposition.

[0124] In some embodiments, the ALD cycle is adjusted by varying the chamber pressure instead of, or in addition to, varying the temperature and / or precursor and / or reactant flows. For example, the chamber pressure may be reduced to slow the deposition rate of the main conductor layer and reduce the conversion of the nucleation layer to elemental metal. Examples of reduced pressures may be between about 5 and about 20 Torr, or at least about 30 to 80% lower than the pressure used to deposit the nucleation layer.

[0125] The exposure time for the gases used to deposit the main conductor layer can vary depending on the flow rate. Non-limiting examples of exposure times range from about 0.1 seconds to about 10 seconds, or from about 0.1 seconds to about 20 seconds, for each gas. In alternating processing pulses, each pulse can have any of the above exposure times.

[0126] The exposure time of the hydrogen gas may be between about 0.1 seconds and about 10 seconds. For example, in some embodiments, the hydrogen may be flowed over the substrate for between about 0.1 seconds and about 10 seconds.

[0127] Oxygen-containing Mo precursor (formula MoO x Cl y For example, in some embodiments, an oxygen-containing Mo precursor may be flowed to the substrate for about 0.1 to about 2 seconds.

[0128] If alternating pulses are performed, a purge operation may be performed between the alternating pulses. The purge may include flowing argon gas or other inert gas for a specified duration, such as between about 0.1 seconds and about 5 seconds.

[0129] In one example embodiment where alternating pulses are performed in operation 309, one cycle of pulses may include: (1) administering hydrogen for 0.1 to 10 seconds; (2) purging with argon gas for 0.1 to 5 seconds; and (3) MoO. x Cl y for 0.1 to 2 seconds; and (4) purging with argon gas for 0.1 to 5 seconds.

[0130] FIG. 3C is an exemplary process flow diagram for practicing certain disclosed embodiments. Operation 301 may be the same as operation 301 in FIGS. 3A and 3B. Operation 303b involves processing an oxide surface of a semiconductor substrate. This oxide surface may be aluminum oxide or silicon oxide, in some embodiments, and may be performed using any of the techniques described above with respect to operation 303a. In some embodiments, operation 303b includes exposing the oxide surface to B2H6 and WF6. In operation 305, a conformal nucleation layer of Mo is deposited by ALD on the processed oxide surface. This may be performed using any of the techniques described with respect to FIG. 3B. In some embodiments, operation 305 includes depositing MoO by ALD on the B2H6 and WF6 processed oxide surface.x N y In operation 319a, a partial main conductor layer is deposited by ALD at low temperature, which is the same temperature as the MoO film deposited in operation 305. x N y The low temperature may be below about 500°C. In operation 319b, the remainder of the main conductor layer is deposited by ALD at a high temperature. In some embodiments, operation 319b involves depositing bulk Mo metal at a temperature above 540°C using an oxygen-containing Mo precursor and hydrogen. In the exposures performed herein, the dosage of the boron-containing gas is about 1E16 atoms / cm of boron. 2 to approximately 1E21 atoms / cm 2 In the exposures performed herein, the dose of fluorine-containing gas is about 1E16 atoms / cm 2 to approximately 1E21 atoms / cm 2 In the exposures performed herein, the dose of W and / or Mo containing gas is about 1E16 atoms / cm 2 to approximately 1E21 atoms / cm 2 This can result in exposure to W or Mo, respectively, during the

[0131] 4 shows an example of an enlarged schematic view of a stack 400 having a substrate 102 (which may be the same as the substrate 102 of FIG. 1A) with a dielectric-metal interface 112 between the dielectric layer 104 and the Mo nucleation layer 108 after deposition of the metal layer 110. The dielectric-metal interface 112 is the same as the dielectric-metal interface 112 of FIG. 1A, the dielectric layer 104 may be the same as the dielectric layer 104 of FIGS. 1A and 1B, the Mo nucleation layer 108 may be the same as the nucleation layer 108 of FIGS. 1A and 1B, and the metal layer 110 may be the same as the metal layer 110 of FIGS. 1A and 1B. In this example, the Mo nucleation layer 108 includes a gradient such that a region 450 of the Mo nucleation layer 108 has an increased amount of "impurities" or non-molybdenum constituent elements such as boron, tungsten, fluorine, oxygen, nitrogen, or chlorine, while the remainder of the Mo nucleation layer 108 is converted to Mo metal when the metal layer 110 is deposited. Without being bound by theory, it is believed that having this region 450 prevents the formation of defects in the dielectric layer 104 that could cause quantum tunneling or data loss in Mo-based gate structures. Device

[0132] Any suitable chamber may be used to implement the disclosed embodiments. Examples of deposition equipment include various systems such as the ALTUS® and ALTUS® Max available from Lam Research Corporation of Fremont, California, or various other commercially available processing systems. The process can be performed in parallel on multiple deposition stations.

[0133] In some embodiments, the nucleation layer deposition process is performed in a first station, which is one of two, five, or more deposition stations located within a single deposition chamber. For example, nucleation layer deposition may be performed in the first station, followed by low-temperature hydrogen reduction of the metal precursor in the second station, and then high-temperature hydrogen reduction of the metal precursor in the third station. Each station may have independent temperature control. In some embodiments, various steps for the process are performed in two different stations of the deposition chamber. For example, using a separate gas supply system to create a local atmosphere at the substrate surface, the substrate may be exposed to NH3 in the first station, and then transferred to the second station for exposure to a metal halide, metal oxyhalide, metal chloride, metal fluoride, or metal oxychloride precursor to deposit the nucleation layer. In some embodiments, the substrate may then be returned to the first station for a second exposure to NH3. The substrate may then be transferred to the second station for exposure to a metal precursor. The substrate may be exposed to NH3 in another station after the initial deposition of the metal chloride or metal oxychloride. This can be repeated as necessary to complete the deposition of the nucleation layer, and then proceed to deposit the bulk layer at the same or a separate station.

[0134] In another example, the nucleation layer deposition process is performed in a first station and higher temperature processing is performed in a second station, so NH3 is piped to the second station for processing. A third station may be used for bulk deposition.

[0135] In some embodiments, multiple chambers are used to perform the methods described herein. For example, deposition of a nucleation layer is performed in a first chamber, and deposition of a bulk metal layer is performed in a second chamber. The two chambers may be connected to a common vacuum chamber, allowing the substrate to be transferred between the chambers without exposure. In alternative embodiments, the chambers are not connected under vacuum, and the substrate is exposed to air during transfer. Oxidation can be reduced in subsequent processing, as described above.

[0136] 5 is a schematic diagram of one embodiment of an atomic layer deposition (ALD) process station 500 having a process chamber body 502. Multiple process stations 500 may be included in a tool environment. For example, FIG. 6 shows one embodiment of a system 600. In some embodiments, one or more hardware parameters of the process station 500, including those discussed in detail below, may be programmatically adjusted by one or more computer controllers 550.

[0137] The process station 500 is in fluid communication with a reactant delivery system 501 for delivering process gases to a distribution showerhead 506. The reactant delivery system 501 includes a mixing vessel 504 for blending and / or conditioning process gases, such as oxygen-containing Mo precursor gases, or NH3 and / or nitrogen gases, for delivery to the distribution showerhead 506. One or more mixing vessel inlet valves 520 may control the introduction of process gases into the mixing vessel 504. The gases are delivered to the process chamber body 502 and reacted in the processing region 507.

[0138] As an example, the embodiment of FIG. 5 includes a vaporization point 503 for vaporizing a liquid reactant supplied to a mixing vessel 504 having a valve 505 directing the reactant from the mixing vessel 504 to the process chamber body 502. In some embodiments, the vaporization point 503 may be a heated vaporizer. Saturated reactant vapor produced from such a vaporizer may condense in downstream delivery piping. Exposure of incompatible gases to the condensed reactant may generate small particles. These small particles can clog piping, interfere with valve operation, contaminate substrates, and so on. Some methods for addressing these issues involve purging and / or evacuating the delivery piping to remove residual reactant. However, purging the delivery piping may increase process station cycle time and reduce process station throughput. Therefore, in some embodiments, the delivery piping downstream of the vaporization point 503 may be heat traced. In some examples, the mixing vessel 504 may also be heat traced. In one non-limiting example, the piping downstream of vaporization point 503 has an increasing temperature profile ranging from about 100° C. to about 150° C. at mixing vessel 504 .

[0139] In some embodiments, the liquid precursor or liquid reactant may be vaporized in a liquid injector. For example, the liquid injector may inject pulses of the liquid reactant into a carrier gas stream upstream of the mixing vessel. In one embodiment, the liquid injector may vaporize the reactant by forcing the liquid from a higher pressure to a lower pressure. In another example, the liquid injector may atomize the liquid into dispersed microdroplets, which are then vaporized in a heated delivery pipe. Smaller droplets vaporize faster than larger droplets, reducing the delay between liquid injection and complete vaporization. Faster vaporization may shorten the length of piping downstream from the vaporization point 503. In one scenario, the liquid injector may be attached directly to the mixing vessel 504. In another scenario, the liquid injector may be attached directly to the distribution showerhead 506.

[0140] In some embodiments, a liquid flow controller (LFC) upstream of the vaporization point 503 may be provided to control the mass flow rate of the liquid for vaporization and delivery to the process station 500. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC may then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, stabilizing the liquid flow through feedback control may take one second or more. This may increase the time required to dose the liquid reactant. Therefore, 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 accomplished by disabling the sense tubes of the LFC and the PID controller.

[0141] 5, the substrate 512 is located below the distribution showerhead 506 and is shown resting on a pedestal 508. The distribution showerhead 506 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to the substrate 512.

[0142] In some embodiments, the pedestal 508 may be raised or lowered to expose the substrate 512 to a volume between the substrate 512 and the distribution showerhead 506. It will be appreciated that the height of the pedestal may be programmatically adjusted by a suitable computer controller 550 in some embodiments.

[0143] In some embodiments, the pedestal 508 may be temperature controlled via a heater 510. In some embodiments, the pedestal 508 may be heated to a temperature between 50° C. and 700° C., depending on the chamber and its function in the overall deposition process. For example, some chambers may have the pedestal 508 set to a temperature between 250° C. and about 400° C., such as for deposition of a nucleation layer or an initial ALD cycle of a main conductor layer, and some chambers may have the pedestal 508 set to a temperature between about 350° C. and about 700° C., or above about 400° C., for deposition of a main conductor layer, particularly portions of the main conductor layer deposited using an oxygen-containing Mo precursor such as MoO2Cl2.

[0144] Additionally, in some embodiments, pressure control of the process station 500 may be provided by a butterfly valve 518. As shown in the embodiment of Figure 5, the butterfly valve 518 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of the process station 500 may be adjusted by varying the flow rate of one or more gases introduced to the process station 500.

[0145] In some embodiments, the position of the distribution showerhead 506 may be adjusted relative to the pedestal 508 to change the volume between the substrate 512 and the distribution showerhead 506. Furthermore, it will be understood that the vertical position of the pedestal 508 and / or the distribution showerhead 506 may be changed by any suitable mechanism within the scope of the present disclosure. In some embodiments, the pedestal 508 may include a rotation axis for rotating the orientation of the substrate 512. It will be understood that in some embodiments, one or more of these example adjustments may be implemented programmatically by one or more suitable computer controllers 550.

[0146] In some embodiments, instructions to the controller 550 may be provided through input / output control (IOC) sequence instructions. In one example, instructions for setting conditions for a process step may be included in the corresponding recipe step of the process recipe. In some cases, process recipe steps may be arranged sequentially so that all instructions for a process step are executed simultaneously with that process step. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe step. For example, a first recipe step may include instructions for setting the flow rates of an inert gas and / or NH3 and / or nitrogen reactant gas, instructions for setting the flow rate of a carrier gas (such as argon), instructions for igniting a plasma, and a time delay instruction for the first recipe step. A second recipe step may include instructions for setting the flow rates of an inert gas and / or a metal halide or metal oxyhalide precursor gas, instructions for setting the flow rate of a carrier gas (such as argon), and a time delay instruction for the second recipe step. A subsequent third recipe step may include instructions for adjusting or stopping the flow rates of the inert gas and / or reactant gas, instructions for adjusting the flow rate of the carrier gas or purge gas, and time delay instructions for the third recipe step. A fourth recipe step may include instructions for adjusting the flow rate of the reducing agent gas, instructions for adjusting the flow rate of the carrier gas or purge gas, and time delay instructions for the fourth recipe step. A subsequent fifth recipe step may include instructions for adjusting or stopping the flow rate of the inert gas and / or second metal halide or metal oxyhalide reactant gas, instructions for adjusting the flow rate of the carrier gas or purge gas, and time delay instructions for the fifth recipe step. It will be understood that these recipe steps may be further subdivided and / or repeated in any suitable manner within the scope of the disclosed embodiments. In some embodiments, the controller 550 may include any of the features related to the system controller 829 of FIG. 8 , described below.

[0147] 6 is a schematic diagram showing a diagram of the gas source and line configuration of a single station of an apparatus suitable for practicing certain disclosed embodiments. While only one station is shown, it will be understood that the apparatus may include one or more of these identical, similar, or different modules for processing substrates. A single station chamber may be used with a single station for processing only one substrate at a time per chamber. In some embodiments, the single station is a station within a multi-station chamber having two or more stations, such as four stations. While a single station is shown, in some embodiments, multiple stations may be used, with the gas source configured to allow a particular gas to enter some stations and not others.

[0148] 6, a process chamber 602 includes a showerhead 606 and a movable pedestal 608 for holding a substrate 612. Pressure control of the process chamber 602 may be provided by a butterfly valve 618 to maintain the process under vacuum. A microvolume 607 created between the showerhead 606 and the movable pedestal 608 may be adjusted by vertically moving the movable pedestal 608 to narrow or widen the space between the showerhead 606 and the movable pedestal 608, which may change the partial pressures of various gases within the microvolume 607.

[0149] The showerhead 606 may be a dual plenum showerhead, as indicated by the two arrows, which indicate that gas flows may enter and exit the showerhead using different lines, which may be done to reduce the possibility of gases interacting with each other within the lines. That is, in some embodiments, gases selected to be introduced into the same line may be selected so that they do not interact with each other and therefore do not form excessive by-products or deposition materials within the line that may contribute to the formation of defects on the substrate 612. In some embodiments, the showerhead 606 may be heated. In some embodiments, the showerhead 606 is both heated and a dual plenum showerhead.

[0150] Upstream of the showerhead 606 is a manifold 686, which can be used to collect gases before delivering them to the showerhead. In some embodiments, the manifold is configured so that gases from different lines do not interact with each other but can be delivered separately to the showerhead 606 and controlled using upstream and downstream valves (not shown). The showerhead 606 can be a single-plenum or multi-plenum showerhead. The multi-plenum showerhead can be a dual-plenum or triple-plenum showerhead. In a dual-plenum showerhead, one plenum can flow W- and / or fluorine-containing gas, Mo-containing precursor, and hydrogen, while the second plenum can flow boron-containing gas, hydrogen, NH3, and argon. Such an embodiment can be used to avoid upstream reactions between Mo- or W-containing precursors and NH3 and boron-containing gas. The manifold 686 can be configured close to the showerhead 606 to allow a high-pressure volume of gas to accumulate before valves are released to deliver the high-pressure gas to the microvolume 607.

[0151] 6 includes multiple gas sources and, for purposes of this example, will be referred to as relating to specific gases. However, it will be understood that the gas sources may include any suitable gases used as precursors or reactants for practicing certain disclosed embodiments, and the configuration may be selected so that delivery of gases to one line is less likely to interact with each other or cause film deposition than mixing with gas sources delivered to another line, and vice versa. Also, while three gas sources are illustrated as being delivered to a single line, and only two separate lines are shown, it will be understood that one or more gas sources may be delivered to a single line, or two or more separate lines may all be delivered to manifold 686 before being introduced to showerhead 606.

[0152] The argon gas source 621a, the WF6 gas source 631a, and the Mo-containing precursor gas source 641a are contained in a gas box 682 separate from the top plate 684. The argon gas source 621a, the WF6 gas source 631a, and the Mo-containing precursor gas source 641a are each routed through corresponding lines to line 690 and then to manifold 686.

[0153] Also provided within the gas box 682 are a diborane (B2H6) gas source 651a, an NH3 gas source 661a, and an argon gas source 671a. The B2H6 gas source 651a, the NH3 gas source 661a, and the argon gas source 671a are each fed via corresponding lines to line 695 and then to manifold 686.

[0154] The flow of argon from the argon gas source 621a is controlled by an argon control valve 620a before being delivered to the argon charge volume 621b, such that the argon accumulates in the argon charge volume 621b before being delivered to the showerhead 606. That is, the gas box 682 may be physically farther from the process chamber 602, but by having the argon charge volume 621b closer to the showerhead 606 and having an argon outlet valve 620b to control the flow of argon from the argon charge volume 621b, better control and increase the pressure of the argon that can be delivered to the showerhead 606 and therefore to the substrate 612.

[0155] Similarly, the flow of WF from the WF gas source 631a is controlled by a WF control valve 630a before being delivered to the WF charge volume 631b, such that tungsten accumulates in the WF charge volume 631b before being delivered to the showerhead 606. That is, the gas box 682 may be physically farther from the process chamber 602, but by having the WF charge volume 631b closer to the showerhead 606 and having a WF outlet valve 630b to control the flow of WF from the WF charge volume 631b, better control and increase the pressure of the WF that can be delivered to the showerhead 606 and therefore to the substrate 612.

[0156] The flow of the Mo-containing precursor from the Mo-containing precursor gas source 641a is controlled by a Mo-containing precursor control valve 640a before delivery. In some embodiments, the Mo-containing precursor can be passed through a generated plasma before being delivered to the process chamber 602. In some embodiments, the Mo-containing precursor is delivered from a remote source. The flow and pressure of the Mo-containing precursor introduced to the showerhead 606 may be adjusted using a molybdenum-containing precursor outlet valve 640b to control the flow of the Mo-containing precursor after it flows through the line toward the showerhead.

[0157] The flow of argon gas, WF, and Mo-containing precursor may be accumulated in manifold 686 via line 690, where it may be delivered to showerhead 606 separately from the gases delivered via line 695 to prevent interactions, for example, between WF and BH, which could form tungsten within the line.

[0158] The flow of B2H6 from the B2H6 gas source 651a is controlled by a B2H6 control valve 650a prior to delivery of B2H6 to the B2H6 charge volume 651b, such that the B2H6 accumulates in the B2H6 charge volume 651b before being delivered to the showerhead 606. The gas box 682 may be physically farther from the process chamber 602 than the manifold 686, but having the B2H6 charge volume 651b closer to the showerhead 606 and having a B2H6 outlet valve 650b to control the flow of B2H6 from the B2H6 charge volume 651b allows for better control and increased pressure of the B2H6 that can be delivered to the showerhead 606 via the manifold 686.

[0159] The flow of NH3 from the NH3 gas source 661a is controlled by an NH3 control valve 660a prior to the delivery of NH3 to the NH3 charge volume 661b so that NH3 can accumulate in the NH3 charge volume 661b before delivery to the showerhead 606. Although the gas box 682 may be physically farther from the process chamber 602 than the manifold 686, having the NH3 charge volume 661b closer to the showerhead 606 and having an NH3 outlet valve 660b to control the flow of NH3 from the NH3 charge volume 661b allows for better control and increased pressure of the NH3 that can be delivered to the showerhead 606 via the manifold 686.

[0160] The flow of argon from the argon gas source 671a is controlled by an argon control valve 670a before being delivered to the argon charge volume 671b, such that the argon accumulates in the argon charge volume 671b before being delivered to the showerhead 606. That is, the gas box 682 may be physically farther from the process chamber 602, but by having the argon charge volume 671b closer to the showerhead 606 and having an argon outlet valve 670b to control the flow of argon from the argon charge volume 671b, better control and increase the pressure of the argon that can be delivered to the showerhead 606 so that it can be delivered to the substrate 612.

[0161] Once the gas is accumulated and pressurized in the charge volume and controllably accessible via the outlet valve, the flow of gas into manifold 686 can be increased, thereby increasing the volume and pressure of gas introduced into microvolume 607. Such an embodiment may be particularly suitable for processing substrates to form three-dimensional NAND structures.

[0162] The apparatus disclosed herein may be set to a sub-atmospheric pressure, such as less than about 760 Torr or less than about 600 Torr, to keep the substrate under vacuum. For a 300 mm wafer, partial pressures of some gases may be delivered to the substrate up to about 1500 Torr.

[0163] The movable stage in combination with the charge volume, lines, and manifold configuration can collectively cause the introduction of gas into a microvolume having a partial pressure from less than about 1 Torr to greater than about 90 Torr. For example, the partial pressure can be between less than 1 Torr for a 3 Torr chamber with a dilute flow, or greater than 90 Torr for a 90 Torr chamber with a pure flow (no carrier gas).

[0164] FIG. 7A is a schematic diagram of a gas source and line configuration for a single station of an apparatus suitable for practicing certain disclosed embodiments. As used in the drawings herein, "CV" refers to charge volume. While only one station is shown, it will be understood that the apparatus may include one or more of these identical, similar, or different modules for processing substrates. A single station chamber may be used with a single station for processing only one substrate at a time per chamber. In some embodiments, the single station is a station within a multi-station chamber having two or more stations, such as four stations. While a single station is illustrated, in some embodiments, multiple stations may be used, with the gas source configured to allow a particular gas to enter some stations and not others.

[0165] 7A, a process chamber 702 includes a showerhead 706 and a movable pedestal 708 for holding a substrate 712. Pressure control of the process chamber 702 may be provided by a butterfly valve 718 to maintain the process under vacuum. A microvolume 707 created between the showerhead 706 and the movable pedestal 708 may be adjusted by vertically moving the movable pedestal 708 to narrow or widen the space between the showerhead 706 and the movable pedestal 708, which may change the partial pressures of various gases within the microvolume 707.

[0166] The showerhead 706 may be a dual plenum showerhead, as indicated by the two arrows, which indicate that gas flows may enter and exit the showerhead using different lines, which may be done to reduce the possibility of gases interacting with each other within the lines. That is, in some embodiments, gases selected to be introduced into the same line may be selected so that they do not interact with each other and therefore do not form excessive by-products or deposition materials within the line that may contribute to the formation of defects on the substrate 712. In some embodiments, the showerhead 706 may be heated. In some embodiments, the showerhead 706 is both heated and a dual plenum showerhead.

[0167] Upstream of the showerhead 706 is a manifold 786, which can be used to collect gases before delivering them to the showerhead. In some embodiments, the manifold is configured so that gases from different lines do not interact with each other but can be delivered separately to the showerhead 706 and controlled using upstream and downstream valves (not shown). The showerhead 706 can be a single-plenum or multi-plenum showerhead. A multi-plenum showerhead can be a dual-plenum or triple-plenum showerhead. A dual-plenum showerhead flows W- and / or fluorine-containing gas, Mo-containing precursor, and hydrogen in one plenum, while using a second plenum to flow boron-containing gas, hydrogen, NH3, and argon. Such an embodiment can be used to avoid upstream reactions between Mo- or W-containing precursors and NH3 and boron-containing gas. The manifold 786 can be configured close to the showerhead 706 to allow a high-pressure volume of gas to accumulate before valves are released to deliver the high-pressure gas to the microvolume 707.

[0168] 7 includes multiple gas sources and, for purposes of this example, will be referred to as relating to specific gases. However, it will be understood that the gas sources may include any suitable gases used as precursors or reactants for practicing certain disclosed embodiments, and the configuration may be selected so that delivery of gases to one line is less likely to interact with each other or cause film deposition than mixing with gas sources delivered to another line, and vice versa. Also, while three gas sources are illustrated as being delivered to a single line, and only two separate lines are shown, it will be understood that one or more gas sources may be delivered to a single line, or two or more separate lines may all be delivered to the manifold 786 before being introduced to the showerhead 706.

[0169] An argon gas source and an optional hydrogen gas source are contained in gas box 782a, which deliver argon gas and optionally hydrogen gas, respectively, to manifold 786 via corresponding lines.

[0170] A source of molybdenum precursor gas is contained in gas box 782b. The Mo-containing precursor gas is routed through corresponding lines to manifold 786.

[0171] The ammonia and argon gas sources are contained in gas box 782c, separate from gas boxes 782a and 782b. The ammonia and argon are flowed from these sources through corresponding lines to manifold 786.

[0172] In some embodiments, an argon gas source may be used by using a chamber purge top as shown in FIG. 7B.

[0173] The flows of argon gas, or optionally hydrogen, Mo-containing precursor, and NH3 are separated to reduce, for example, interactions between the Mo-containing precursor and hydrogen, which can form Mo in the lines.

[0174] Once the gas is accumulated and pressurized in the charge volume and controllably accessible via the outlet valve, the flow of gas into manifold 786 can be increased, thereby increasing the volume and pressure of gas introduced into microvolume 707. Such an embodiment may be particularly suitable for processing substrates to form three-dimensional NAND structures.

[0175] The apparatus disclosed herein may be set to a sub-atmospheric pressure, such as less than about 760 Torr or less than about 600 Torr, to keep the substrate under vacuum. For a 300 mm wafer, partial pressures of some gases may be delivered to the substrate up to about 1500 Torr.

[0176] The movable stage in combination with the charge volume, lines, and manifold configuration can collectively cause the introduction of gas into a microvolume having a partial pressure from less than about 1 Torr to greater than about 90 Torr. For example, the partial pressure can be between less than 1 Torr for a 3 Torr chamber with a dilute flow, or greater than 90 Torr for a 90 Torr chamber with a pure flow (no carrier gas).

[0177] 7C is an exemplary schematic diagram of a gas source and line configuration diagram for a single station of an apparatus suitable for practicing certain disclosed embodiments. "Stn2," "Stn3," and "Stn4" refer to stations, which may be stations such as process chamber body 502 of FIG. 5, process chamber 602 of FIG. 6, and process chamber 702 of FIG. 7A. Gas box 792a contains argon and hydrogen gas sources, and gas box 792b contains a Mo-containing gas source, each routed to different charge volumes and manifolds of the corresponding stations, allowing different stations to perform different operations, each configured under different process conditions.

[0178] The hardware described above is MoO x N yThese exemplary chambers and systems can be used to achieve processing of memory device wordline dielectric surfaces for boron, fluorine, tungsten-containing species, and other non-molybdenum constituent element sources prior to deposition of a nucleation layer such as BH, fluorine-containing species, and / or a main conductor layer of elemental Mo. These exemplary chambers and systems can be used to deliver BH, hydrogen, and argon to a semiconductor substrate in ALD or CVD modes. In some embodiments, a gas charge volume(s) is used to deliver pulses of a gas mixture having BH, hydrogen, argon, nitrogen, and combinations thereof to a semiconductor wafer in ALD mode. This may expose the wafer surface to BH, hydrogen, and nitrogen, and may also provide boron hydride (BH) to the wafer surface. x ) can be adsorbed. x can diffuse directly into the substrate or react further.

[0179] In various embodiments, hardware such as that described above can be used to deliver WF-argon (WF-Ar) to a semiconductor substrate in ALD or CVD modes. In some embodiments, a gas charge volume(s) is used to deliver pulses of a WF-Ar gas mixture to a semiconductor wafer in ALD mode (W and F exposure). Tungsten hexafluoride exposure results in the formation of tungsten fluoride (WF x ) can be adsorbed onto the wafer surface. x can diffuse directly to the substrate or react further.

[0180] In various embodiments, the hardware is configured to deliver one or more ALD pulses of a (B2H6-H2-Ar-N2) gas mixture alternating with pulses of (WF6-Ar). In some embodiments, this is in combination with W metal, tungsten boride (WB x ), W.F. x H2, B2H6, or BH, which can result in the formation of subfluorides and adsorbed F, HF, and adsorbed hydrogen. x After the WF6 reaction with B2H6 / H2, W metal, WB x , W.F. x, F, and HF are available at the semiconductor surface and can diffuse into the substrate.

[0181] As noted above, although a multi-station chamber is described herein, certain disclosed embodiments can be implemented in a single-chamber apparatus. For example, in a single-chamber apparatus, gas delivery hardware can be used to expose a semiconductor surface to pulses of WF / Ar and BH / H / NH through separate WF-Ar, BH / H / N / Ar, and NH / H / Ar gas charge volumes that deliver the gas to a showerhead above the wafer. In various embodiments, a single plenum showerhead is used. In various embodiments, a dual plenum showerhead is used. For example, a dual plenum showerhead can have WF / Ar+MoO in one plenum and a BH / H / N / Ar gas charge volume in the other. x Cl y +H2, and the other plenum may contain B2H6 / H2 / NH3 / Ar, which may be used to avoid upstream reactions of Mo or W precursors with NH3 and B2H6. In various embodiments, the gas charge volume can be used with a continuous trickle purge cleanout control valve outlet.

[0182] In various embodiments, the WF / Ar, BH / H / Ar / N, and NH / H / Ar gas delivery hardware can be used in single-wafer or multi-station volumetric chambers. In various embodiments, the WF / Ar, BH / H / Ar / N, and NH / H / Ar gas delivery hardware can be used in the first deposition station in a multi-station deposition chamber.

[0183] Various disclosed embodiments may be implemented in a multi-chamber apparatus. For example, one or more chambers may be configured to generate WFB exposure on a semiconductor substrate. The one or more chambers may include a nucleation layer, MoO, on the semiconductor substrate. x N y , or MoO xN y The one or more chambers may be configured to cause deposition of Mo metal on a semiconductor substrate. The one or more chambers may be configured to cause deposition of MoO x N y and may be configured to cause deposition of metallic Mo.

[0184] FIG. 8 is a block diagram of a processing system suitable for performing deposition processes in accordance with embodiments described herein. System 800 includes a transfer module 803. Transfer module 803 provides a clean, pressurized environment to minimize the risk of contamination of the substrate being processed as it moves between various reactor modules. Mounted on transfer module 803 is a multi-station reactor 809 capable of performing the ALD deposition described herein. Multi-station reactor 809 may include multiple stations 811, 813, 815, and 817 that sequentially perform these operations. For example, multi-station reactor 809 may be configured such that stations 811 and 813 perform nucleation layer deposition, and stations 813 and 815 perform bulk layer deposition. Each deposition station may include a heated wafer pedestal and a showerhead, distribution plate, or other gas inlet.

[0185] The transfer module 803 may also include one or more single- or multi-station modules 807 capable of performing plasma or chemical (non-plasma) pre-cleaning. This module may also be used for various other processes, such as reducing agent soaks. The system 800 also includes one or more (in this case, two) wafer source modules 801 where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 819 first removes wafers from the source modules 801 to a load lock 821. A wafer transport device (typically a robot arm unit) in the transfer module 803 moves wafers from the load lock 821 to between modules mounted on the transfer module 803.

[0186] In some embodiments, a high temperature showerhead is employed.

[0187] This allows the use of a single-plenum showerhead rather than a dual one. By maintaining the wetted surfaces inside the showerhead at temperatures above 150°C or 200°C, NH3 and metal oxychloride or metal chloride precursors can be used in a single-plenum showerhead without condensing ammonium chloride (NH4Cl). Alternatively, a dual-plenum showerhead can be used, where NH3 can be delivered from one plenum and the metal chloride or oxychloride precursor from the other plenum.

[0188] As mentioned above, in some embodiments, deposition of both metal (nitride) nucleation and pure metal in a single process chamber reduces the amount of H, metal (oxychloride), and their by-products (HCl, OCl). x , metal-Cl x The deposited metal + O x +NH x +Cl xThis facilitates the conversion of the nucleation film to pure metal. This may be done in a multi-station reactor at a lower temperature in the first deposition station and at lower or higher temperatures in subsequent deposition stations, as described above. In some embodiments, each deposition station in a multi-station deposition reactor can be isolated from one another by shaping the showerhead and pedestal so that, in the pedestal-raised process position, the two assemblies form a small process volume above the wafer and a very narrow gap isolating the process volume from the main chamber. The narrow gap at the edge of the process volume can be augmented with an inert gas purge barrier to make it difficult for gases to diffuse from the main chamber into the process volume. The narrow gap at the edge of the process volume can incorporate a localized pumping plenum to prevent process gases from entering the main chamber, eliminating the risk of deposition or particle generation within the main chamber. The narrow edge gap itself can eliminate the risk of gases from the main chamber diffusing back into the wafer processing volume, thereby eliminating crosstalk between stations.

[0189] As mentioned above, in certain embodiments, the system includes two different deposition chambers. For example, referring to FIG. 8, two deposition chambers may be mounted on transfer module 803. In such embodiments, each deposition chamber may be a single or multi-station chamber. Furthermore, two deposition chambers that are not under a common vacuum may be employed.

[0190] In certain embodiments, a system controller 829 is employed to control process conditions during deposition. The controller will typically include one or more memory devices and one or more processors. The processor may include a central processing unit (CPU) or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0191] The controller may control all activity of the deposition apparatus. The system controller executes system control software containing sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels (if used), wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory devices associated with the controller may also be employed in some embodiments.

[0192] Typically, there will be a user interface associated with the controller, which may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0193] System control logic may be configured in any suitable manner. Generally, logic can be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry may be hard-coded or provided as software. Instructions may be provided by "programming." Such programming is understood to include any form of logic, including hard-coded logic in digital signal processors, application-specific integrated circuits, and other devices in which specific algorithms are implemented as hardware. Programming is also understood to include software or firmware instructions that can be executed on a general-purpose processor. System control software may be coded in any suitable computer-readable programming language. Alternatively, control logic may be hard-coded into the controller. For these purposes, application-specific integrated circuits, programmable logic devices (e.g., field-programmable gate arrays, or FPGAs), etc. may be used. In the following discussion, where "software" or "code" is used, functionally comparable hard-coded logic may be used instead.

[0194] Computer program code for controlling deposition and other processes in a process sequence can be written in any conventional computer-readable programming language, such as assembly language, C, C++, Pascal, Fortran, etc. The compiled object code or script is executed by a processor to perform the tasks specified in the program.

[0195] The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, and chamber wall temperature, etc. These parameters may be provided to the user in the form of a recipe and entered using a user interface.

[0196] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller, and signals for controlling the process are output to analog and digital output connections of the deposition device.

[0197] The system software may be designed or configured in a variety of ways. For example, various chamber component subroutines or control objects may be written to control the operation of the chamber components necessary to carry out the deposition processes described herein. Examples of programs or portions of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0198] In some implementations, the controller 829 is part of a system that may be part of the examples described above. Such systems may include semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of semiconductor wafers or substrates. This electronics may be referred to as a “controller,” which may control various components or subcomponents of one or more systems. Depending on the processing requirements and / or type of system, the controller 829 may be programmed to control any of the processes disclosed herein, such as delivery of process 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, position and operation settings, wafer loading and unloading into and out of the tool, and wafer loading and unloading into and out of other transfer tools and / or load locks connected or interfaced to the particular system.

[0199] Broadly speaking, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that, for example, receive instructions, issue instructions, control operations, enable cleaning operations, and enable endpoint metrology. 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 (e.g., software) that execute the program instructions. Program instructions may be instructions communicated to the controller in the form of various personalizations (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer types.

[0200] In some implementations, the controller 829 may be part of or coupled to a computer that is integrated into, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller 829 may be all or part of a host computer system in the “cloud” or at a fab that allows remote access to wafer processing. This computer may provide remote access to the system to monitor the current progress of manufacturing operations, review the history of past manufacturing operations, and review trends or performance metrics from multiple manufacturing operations to modify parameters of a current process, set up processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows input 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 defining parameters for each processing step performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed or the type of tool the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by including one or more separate controllers networked together and working toward a common purpose, such as the processes and controls described herein. An example of a distributed controller for such a purpose includes one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., at the platform level or as part of a remote computer) combined to control the processes on the chamber.

[0201] Without limitation, exemplary 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 physical vapor deposition (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 system that may be associated with or used in the fabrication and / or production of semiconductor wafers.

[0202] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, other controllers, or tools used in material transport to bring containers of wafers into and out of tool locations and / or load ports within a semiconductor production factory.

[0203] The controller 829 may include a variety of programs. A substrate positioning program may include program code for controlling chamber components used to load the substrate onto a pedestal or chuck and control spacing between the substrate and other chamber components, such as gas inlets and / or targets. A process gas control program may include code for controlling gas composition and flow rates, and optionally for flowing gas into the chamber prior to deposition to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber, for example, by adjusting a throttle valve in the chamber's exhaust system. A heater control program may include code for controlling current to a heating unit used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas, such as helium, to the wafer chuck.

[0204] Examples of chamber sensors that may be monitored during deposition include mass flow controllers located in the pedestal or chuck, pressure sensors (such as pressure gauges), thermocouples, etc. Appropriately programmed feedback and control algorithms may be used in conjunction with data from these sensors to maintain desired process conditions.

[0205] The above describes the implementation of embodiments of the present disclosure in single or multi-chamber semiconductor processing tools.

[0206] The foregoing is a description of the implementation of the disclosed embodiments in single or multi-chamber semiconductor processing tools. The apparatus and processes described herein may be used in combination with lithographic patterning tools or processes, for example, for the manufacture or production of semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, but not necessarily, such apparatus / processes are used or performed together in a common manufacturing facility. Lithographic patterning of films typically involves some or all of the following steps, each with several possible tools: (1) application of photoresist onto a workpiece (i.e., substrate) using a spin-on or spray-on tool; (2) curing of the photoresist using a hotplate, furnace, or UV curing tool; (3) exposure of the photoresist to visible, ultraviolet, or X-ray light using a tool such as a wafer stepper; (4) patterning of the resist by growing it to selectively remove it using a tool such as a wet bench; (5) transfer of the resist pattern to the underlying film or workpiece using a dry etching tool or a plasma-assisted etching tool; and (6) removal of the resist using a tool such as an RF or microwave plasma resist stripper.

[0207] In the above description and claims, numerical ranges include the endpoints of the range. For example, "a thickness between 1 and 5 nm" includes 1 nm and 5 nm. Similarly, ranges expressed with a prime include the endpoints of the range. experiment

[0208] Different Mo and MoO x N y The atomic composition of three different substrates with stacks was evaluated. Figure 9 shows the MoO x N y The graph shows the results of the evaluation of the Mo-oxide interface between the MoO x N y The closeness of the interface between the nucleation layer and the dielectric oxide on the right is shown.

[0209] In 910, the main conductor layer Mo was converted to MoO by the administration of oxygen-containing Mo precursor and reduced hydrogen. x N y It was deposited on a nucleation layer, resulting in a low oxygen content at the Mo-oxide interface.

[0210] In 920, the main conductor layer Mo was converted to MoO by the administration of oxygen-containing Mo precursor and further reduced (13% less than in 910) hydrogen. x N y Arrows 922 indicate that the oxide content at the interface is higher than 910.

[0211] In 930, the dosing of oxygen-containing Mo precursor and more reduced (26% less than in 910) hydrogen converted the main conductor layer Mo to MoO x N y Arrow 931 indicates that the oxygen content in the main conductor layer Mo is even higher than in 910 or 920. Similarly, arrow 932 indicates that there is more chlorine at the interface (although still in small amounts).

[0212] These results indicate that hydrogen dosage (e.g., flow rate and / or exposure duration) can affect the composition of the film at the Mo oxide interface. conclusion

[0213] Although the foregoing embodiments have been described in some detail for 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 considered to be illustrative and not restrictive, and the present embodiments are not limited to the details set forth herein.

Claims

1. A film deposition method, A substrate having an oxide material formed on the top is provided. At least one of a liner layer and a nucleation layer is formed on the oxide material. The method involves supplying a molybdenum-containing gas and a reducing gas to the substrate having the liner layer or nucleation layer formed on top of the liner layer or nucleation layer, in order to form a molybdenum film on the liner layer or nucleation layer. A film deposition method comprising a molybdenum film consisting of a first layer and a second layer, wherein the first layer is deposited at a temperature lower than the temperature of the second layer.

2. A film deposition method according to claim 1, A film deposition method comprising soaking before forming at least one of the liner layer and the nucleation layer.

3. A film deposition method according to claim 1, A film deposition method wherein at least one of the liner layer and the nucleation layer is deposited at a temperature lower than the deposition temperature used to form the molybdenum film.

4. A film deposition method according to claim 1, A film deposition method comprising depositing the first layer on the liner layer or nucleation layer, and depositing the second layer on the first layer.

5. A film deposition method according to claim 1, A film deposition method wherein the liner layer or nucleation layer has a metal-to-impurity atomic ratio between approximately 100:1 and 1:4 after the deposition of the molybdenum film.

6. A film deposition method according to claim 1, A film deposition method wherein the liner layer or nucleation layer is a molybdenum-containing layer.

7. A film deposition method according to claim 1, The first layer is deposited at a temperature of less than 500°C in a film deposition method.

8. A film deposition method according to claim 1, The second layer is deposited at a temperature exceeding 540°C in a film deposition method.

9. A film deposition method according to claim 1, The molybdenum film is crystalline, and the film deposition method is described above.

10. A film deposition method according to claim 1, The molybdenum film is deposited using a film deposition method that includes less than 1 (atomic)% of non-molybdenum impurities.

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