Improving gap-fill performance of DRAM word lines

Abstract

A method for forming a memory device is described. A molybdenum silicide nucleation layer is formed and the substrate is immersed in a titanium precursor prior to a bulk molybdenum gap-fill process. In another embodiment, a molybdenum silicide film is formed in a first process cycle and a second process cycle is performed in which the substrate is exposed to a titanium precursor. In a further embodiment, a substrate having at least one feature thereon is exposed to a first titanium precursor and a nitrogen-containing reactant. The substrate is then immersed in a second titanium precursor and then exposed to a first molybdenum precursor, followed by exposure to silane to form a molybdenum silicide layer on the surface of the substrate.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to the field of semiconductor devices and semiconductor device fabrication. In particular, embodiments relate to methods used for dynamic random access memory (DRAM) word line processing. [Background technology]

[0002] Electronic devices, such as personal computers, workstations, computer servers, mainframes, and other computer-related equipment such as printers, scanners, and hard disk drives, use memory devices that provide ample data storage capacity with low power consumption. There are two main types of random access memory cells suitable for use in electronic devices: dynamic and static. Dynamic random access memory (DRAM) can be programmed to store a voltage representing one of two binary values, but requires periodic reprogramming or "refreshing" to maintain this voltage for more than a very short period of time. Static random access memory (SRAM) is so named because it does not require periodic refreshing.

[0003] DRAM memory circuits are fabricated by replicating millions of identical circuit elements, known as DRAM cells, on a single semiconductor wafer. Each DRAM cell is an addressable location that can store one bit of data (binary digit). In its most common form, a DRAM cell consists of two circuit components: a field-effect transistor (FET) and a capacitor.

[0004] Fabrication of a DRAM cell involves the fabrication of a transistor, a capacitor, and three contacts: one for each of the bit line, word line, and reference voltage. DRAM fabrication is a highly competitive business. There is constant pressure to reduce the size of individual cells and increase memory cell density, particularly to allow more memory to be packed onto a single memory chip for densities beyond 256 megabits. Limitations to cell size reduction include the routing of both the active and passive word lines through the cell, the size of the cell capacitor, and compatibility with array and non-array devices.

[0005] In fabrication, DRAM wordlines must be able to withstand the harsh thermal conditions often required for later circuit processing steps. However, due to poor adhesion between the metal and trench structures, void formation and delamination of the metal fill are often observed during high-temperature post-annealing processes.

[0006] Therefore, there is a need for a gapfill method that produces low resistance buried wordlines in DRAM cells that can withstand further processing conditions without delamination. Accordingly, there is a need for a method of fabricating DRAM devices that improves metal gapfill performance. Summary of the Invention

[0007] One or more embodiments of the present disclosure are directed to a method of forming a film. In one embodiment, the method includes forming a molybdenum silicide film in a process cycle including sequentially exposing a substrate to a molybdenum precursor, a purge gas, a silane precursor, and a purge gas, wherein the substrate has at least one feature thereon, and immersing the substrate in a titanium precursor, wherein the substrate is immersed prior to the process cycle or the substrate is immersed after the process cycle.

[0008] Another embodiment of the present disclosure is directed to a method of forming a film. In one or more embodiments, the method includes forming a molybdenum silicide film in a first process cycle including sequentially exposing a substrate to a molybdenum precursor, a purge gas, a silane reactant, and a purge gas, where the substrate has at least one feature thereon, and performing a second processing cycle including exposing the substrate to a titanium precursor and ammonia.

[0009] Further embodiments of the present disclosure are directed to a method of forming a film. In one or more embodiments, the method includes exposing a substrate having at least one feature thereon to a first titanium precursor and ammonia, immersing the substrate in a second titanium precursor, exposing the substrate to a first molybdenum precursor, and exposing the substrate to silane to form a molybdenum silicide layer on a surface of the substrate.

[0010] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above can be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure, since the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 illustrates a process flow diagram of a method according to one or more embodiments. [Figure 2] FIG. 1 illustrates a process flow diagram of a method according to one or more embodiments. [Figure 3] FIG. 1 illustrates a process flow diagram of a method according to one or more embodiments. [Figure 4]FIG. 1 illustrates a process flow diagram of a method according to one or more embodiments. [Figure 5] FIG. 1 illustrates a process flow diagram of a method according to one or more embodiments. [Figure 6] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. [Figure 7] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. [Figure 8] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. [Figure 9] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. [Figure 10] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. [Figure 11] FIG. 1 is a cross-sectional view of a device according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of example embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein, but may include deviations in shape that result, for example, from manufacturing.

[0013] Before describing several example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.

[0014] As used herein and in the appended claims, the term "substrate" refers to a surface, or portion of a surface, on which a process acts. Those skilled in the art will also understand that it may refer to only a portion of a substrate, unless the context clearly indicates otherwise. Additionally, references to depositing on a substrate can refer to both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0015] As used herein, "substrate" refers to a substrate or a material surface formed on a substrate on which a film treatment is performed during a manufacturing process. For example, substrate surfaces on which treatments can be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates can be exposed to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam cure, and / or bake the substrate surface. In addition to film treatments performed directly on the substrate surface itself, in the present disclosure, any of the disclosed film treatment steps can be performed on an underlayer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" is intended to include the underlayer as the context indicates.

[0016] According to one or more embodiments, the term "on" with respect to a film or layer of a film includes the film or layer being directly on a surface, e.g., a substrate surface, as well as having one or more underlying layers between the film or layer and the surface, e.g., a substrate surface. Thus, in one or more embodiments, the phrase "on the substrate surface" is intended to include one or more underlying layers. In other embodiments, the phrase "directly on" refers to a layer or film in contact with a surface, e.g., a substrate surface, without an intervening layer. Thus, the phrase "a layer directly on the substrate surface" refers to a layer in direct contact with the substrate surface, without an intervening layer.

[0017] As used herein and in the appended claims, the terms "precursor," "reactant," "reactive gas," and the like are used interchangeably to refer to any gas species capable of reacting with the substrate surface.

[0018] As used herein, "atomic layer deposition" or "cyclic deposition" refers to the sequential exposure of two or more reactive compounds to deposit a layer of material on a substrate surface. The substrate, or portions of the substrate, are separately exposed to two or more reactive compounds introduced into the reaction zone of a processing chamber. In a time-domain ALD process, exposure to each reactive compound is separated by a time delay to allow each compound to adhere to and / or react on the substrate surface and then be purged from the processing chamber. These reactive compounds are sequentially exposed to the substrate. In a spatial ALD process, different portions of the substrate surface or materials on the substrate surface are simultaneously exposed to two or more reactive compounds such that a given point on the substrate is not substantially exposed to more than one reactive compound at the same time. As used herein and in the appended claims, the term "substantially" used in this context means that, as understood by those skilled in the art, small portions of the substrate may be exposed to multiple reactive gases simultaneously due to diffusion, and simultaneous exposure is not intended.

[0019] In one aspect of a time-domain ALD process, a first reactive gas (i.e., a first precursor or compound A, e.g., an aluminum precursor) is pulsed into the reaction zone, followed by a first time delay. Then, a second precursor or compound B (e.g., an oxidizer) is pulsed into the reaction zone, followed by a second time delay. During each time delay, a purge gas, such as argon, is introduced into the processing chamber to purge the reaction zone or otherwise remove residual reactive compounds or reaction byproducts from the reaction zone. Alternatively, the purge gas can flow continuously throughout the deposition process, such that only the purge gas flows during the time delay between pulses of reactive compounds. The reactive compounds are alternately pulsed until a desired film or film thickness is formed on the substrate surface. In either scenario, the ALD process pulsing compound A, purge gas, compound B, and purge gas is a cycle. The cycle can start with either compound A or compound B and continue with each order of the cycle until a film with a predetermined thickness is achieved.

[0020] In an embodiment of a spatial ALD process, a first reactive gas and a second reactive gas (e.g., nitrogen gas) are simultaneously supplied to a reaction zone but separated by an inert gas curtain and / or a vacuum curtain, and the substrate is moved relative to the gas supply system so that a given point on the substrate is exposed to the first reactive gas and the second reactive gas.

[0021] As used herein, "chemical vapor deposition" refers to a process in which a substrate surface is exposed to precursors and / or co-reagents simultaneously or substantially simultaneously. As used herein, "substantially simultaneously" refers to either co-flow or where there is overlap for the majority of the precursor exposure.

[0022] As used herein throughout the specification, "substantially simultaneously" means that the majority of the duration of the first reactive compound exposure overlaps with the second reactive compound exposure.

[0023] As used herein, the term "purging" includes any suitable purge process that removes unreacted precursors, reaction products, and by-products from the process region. A suitable purge process includes moving the substrate through a gas curtain to a portion or sector of the processing region that contains no or substantially no reactants. In one or more embodiments, purging the processing chamber comprises applying a vacuum. In some embodiments, purging the processing region comprises flowing a purge gas over the substrate. In some embodiments, the purge process comprises flowing an inert gas. In one or more embodiments, the purge gas is selected from one or more of nitrogen (N), helium (He), and argon (Ar). In some embodiments, purging the substrate surface or reaction chamber may be carried out for a duration in the range of 0.2 seconds to 30 seconds, 0.2 seconds to 10 seconds, 0.2 seconds to 5 seconds, 0.5 seconds to 30 seconds, 0.5 seconds to 10 seconds, 0.5 seconds to 5 seconds, 1 second to 30 seconds, 1 second to 10 seconds, 1 second to 5 seconds, 5 seconds to 30 seconds, 5 seconds to 10 seconds, or 10 seconds to 30 seconds.

[0024] As used herein, the term "dynamic random access memory" or "DRAM" refers to a memory cell that stores data bits by storing packets of charge (i.e., binary 1) or no charge (i.e., binary 0) on a capacitor. The charge is gated onto the capacitor through an access transistor and sensed by turning on the same transistor and examining the voltage perturbation created by dumping the charge packet on an interconnect line on the transistor output. Thus, a single DRAM cell is made from one transistor and one capacitor. DRAM devices are formed from an array of DRAM cells. Rows of access transistors are connected by word lines, and transistor inputs / outputs are connected by bit lines. Historically, DRAM capacitors evolved from planar polysilicon-oxide-substrate plate capacitors to 3D structures, which branched into "stacked" capacitors with both plates above the substrate and "trench" capacitors that use an etched cavity in the substrate as the common plate.

[0025] Current DRAM buried wordline (bWL) processes involve a titanium nitride (TiN) and tungsten (W) stack. For further scaling of bWL dimensions, one focus is to remove the titanium nitride barrier from the stack to form a barrier-less metal fill in the trench structure. However, due to poor adhesion between the metal and trench structures, void formation and delamination of the metal fill are often observed during high-temperature post-annealing processes. Such voids and delamination are undesirable because they cause problems for subsequent planarization or etching processes. Voids and delamination also contribute to increased stack resistance. Therefore, embodiments of the present disclosure are directed to improving the gap-fill performance of DRAM buried wordlines (BWLs) so as to maintain good line-bending performance (i.e., line-bending less than 2 nm), reduce interface roughness, and lower film resistivity.

[0026] Traditionally, DRAM cells have buried high work function metal structures in a buried word line structure. In DRAM devices, bit lines are formed in a metal level located above the substrate, and word lines are formed in a polysilicon gate level at the surface of the substrate. In buried word line (bWL) devices, the word lines are buried below the surface of the semiconductor substrate using metal as the gate electrode.

[0027] The choice of metal to be used as the gate electrode can significantly affect device performance. While not intending to be bound by theory, it is believed that the use of low-melting-point metals with low resistivity advantageously provides bWL DRAMs with reduced resistance. However, when exposed to the thermal process requirements used in fabricating bWL DRAMs, these materials are often found to delaminate from the surface. Delamination can affect the final array resistance and cause reliability issues.

[0028] Some embodiments of the present disclosure advantageously form memory devices with good line bending performance (i.e., line bending less than 2 nm), reduced interface roughness, and high quality gap fill with lower film resistivity. In some embodiments, the buried word lines have a resistivity of 45 μΩ-cm @ 50 Å.

[0029] 1-5 illustrate process flow diagrams of methods according to one or more embodiments of the present disclosure.

[0030] 1, one or more embodiments of the present disclosure are directed to a method 100 of depositing a film. The method illustrated in FIG. 1 represents an atomic layer deposition (ALD) process in which a substrate or substrate surface is sequentially exposed to reactive gases in a manner that prevents or minimizes gas-phase reaction of the reactive gases. In some embodiments, the method comprises a chemical vapor deposition (CVD) process in which reactive gases are mixed in a processing chamber to enable gas-phase reaction of the reactive gases and deposition of a thin film.

[0031] In one or more embodiments, method 100 includes, in operation 102, immersing a substrate in a solution of a titanium precursor. In some embodiments, the titanium precursor may comprise a titanium halide selected from one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), and titanium bromide (TiBr). In some embodiments, the substrate may be immersed in the titanium precursor for a time period ranging from greater than 0 seconds to 60 seconds. In some embodiments, the substrate may be immersed in the titanium precursor at a pressure ranging from 3 Torr to 50 Torr and at a temperature ranging from 300° C. to 600° C., or from 400° C. to 550° C.

[0032] In operation 104, the substrate surface or the processing chamber can optionally be purged of titanium chloride.

[0033] As used in this manner, the term "processing chamber" also includes a portion of the processing chamber adjacent to the substrate surface that does not encompass the complete internal volume of the processing chamber. For example, in spatially separated processing chamber sectors, the portion of the processing chamber adjacent to the substrate surface is purged of molybdenum precursor by any suitable technique, including, but not limited to, moving the substrate through a gas curtain to a portion or sector of the processing chamber that contains no or substantially no molybdenum precursor. In one or more embodiments, purging the processing chamber comprises applying a vacuum. In some embodiments, purging the processing chamber comprises flowing a purge gas over the substrate. In some embodiments, the portion of the processing chamber refers to a micro-volume or small-volume process station within the processing chamber. The term "adjacent to" with respect to the substrate surface refers to the physical space next to the surface of the substrate that can provide sufficient space for surface reactions (e.g., precursor adsorption) to occur. In one or more embodiments, the purge gas is selected from one or more of nitrogen (N), helium (He), and argon (Ar).

[0034] In deposition 106, a process is performed to deposit a molybdenum-containing film on a substrate (or substrate surface). The deposition process can include one or more treatments to form a film on the substrate. In operation 108, the substrate (or substrate surface) is exposed to a molybdenum precursor, such as molybdenum dioxide dichloride (MoOCl), to deposit a film on the substrate (or substrate surface). The molybdenum precursor can be any suitable molybdenum-containing compound that can react with the substrate surface (in other words, adsorb or chemisorb onto the substrate surface) to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dioxide dichloride (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum.

[0035] Deposition 106 can be carried out at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the molybdenum precursor at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400°C to 550°C.

[0036] As used herein, "substrate surface" refers to any substrate surface upon which a layer may be formed. A substrate surface may have one or more features formed therein, one or more layers formed thereon, and combinations thereof. The substrate (or substrate surface) may be pretreated prior to deposition of a molybdenum-containing layer, for example, by polishing, etching, reducing, oxidizing, halogenating, hydroxylating, annealing, calcining, etc.

[0037] In operation 110, the processing chamber or the substrate surface is optionally purged to remove unreacted molybdenum precursor, reaction products, and by-products. Purging the processing chamber in operation 110 can be the same process as purging in operation 104 or can be a different process than purging in operation 104. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the areas adjacent to the substrate surface.

[0038] In process 112, the substrate (or substrate surface) is exposed to a silane reactant to form a molybdenum silicide film on the substrate. In some embodiments, the molybdenum silicide film is a nucleation film. The silane reactant may comprise any suitable silane reactant known to those skilled in the art. In some embodiments, the silane reactant is selected from the group consisting of silane, disilane, trisilane, tetrasilane, higher silanes, and substituted silanes. The silane reactant may react with molybdenum-containing species on the substrate surface to form a molybdenum silicide film. The exposure to the reactant in process 112 may be performed at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the silane reactant at a pressure ranging from 10 Torr to 50 Torr and at a temperature ranging from 400°C to 550°C.

[0039] In operation 114, the processing chamber is optionally purged after exposure to the reactants. Purging the processing chamber in operation 114 can be the same process as purging in operation 110 or can be a different process than purging in operation 110. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted silane reactants, reaction products, and by-products from the areas adjacent to the substrate surface.

[0040] In decision 116, the thickness of the deposited film or the number of cycles of the molybdenum precursor and the silane reactant is considered. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 100 proceeds to bulk molybdenum gap-fill process 118. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 100 returns to deposition 106 and continues by again exposing the substrate surface to the molybdenum precursor in process 108. Bulk molybdenum gap-fill process 118 may comprise any suitable gap-fill process known to those skilled in the art. In some embodiments, the gap-fill process comprises exposing the substrate to a molybdenum precursor, e.g., molybdenum dioxide dichloride (MoOCl), and a reactant, e.g., hydrogen (H), to form a bulk molybdenum film. The molybdenum precursor may be any suitable molybdenum-containing compound. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dioxide dichloride (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In some embodiments, the substrate (or substrate surface) is exposed to the molybdenum precursor at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400°C to 550°C.

[0041] In some embodiments, the gap filling process of operation 118 may be a bottom-up gap filling process, while in other embodiments, the gap filling process may be a traditional gap filling process.

[0042] In one or more embodiments, after the gap fill process, the substrate is annealed in operation 119. Annealing may comprise any suitable annealing process known to those skilled in the art. In one or more embodiments, annealing is performed in an atmosphere of argon (Ar) or hydrogen (H) gas at a temperature ranging from 600° C. to 1200° C.

[0043] 2, one or more alternative embodiments of the present disclosure are directed to a method 120 of depositing a film. The method illustrated in Figure 2 also represents an atomic layer deposition (ALD) process.

[0044] Method 120 begins with deposition 122, in which a process is performed to deposit a molybdenum-containing film on a substrate (or substrate surface). The deposition process can include one or more treatments to form a film on the substrate. In treatment 124, the substrate (or substrate surface) is exposed to a molybdenum precursor to deposit a film on the substrate (or substrate surface). The molybdenum precursor can be any suitable molybdenum-containing compound that can react with (in other words, adsorb or chemisorb onto) the substrate surface to leave molybdenum-containing species on the substrate surface. The molybdenum precursor can be any suitable molybdenum-containing compound that can react with (in other words, adsorb or chemisorb onto) the substrate surface to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dichloride dioxide (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In one or more embodiments, the molybdenum precursor comprises molybdenum dichloride dioxide (MoOCl2).

[0045] In operation 126, the processing chamber or the substrate surface is optionally purged to remove unreacted molybdenum precursor, reaction products, and by-products. Purging the processing chamber in operation 126 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0046] In process 128, the substrate (or substrate surface) is exposed to a silane reactant to form a molybdenum silicide film on the substrate. In some embodiments, the molybdenum silicide film is a nucleation film. The silane reactant may comprise any suitable silane reactant known to those skilled in the art. In some embodiments, the silane reactant is selected from the group consisting of silane, disilane, trisilane, tetrasilane, higher silanes, and substituted silanes. The silane reactant may react with molybdenum-containing species on the substrate surface to form a molybdenum silicide film. The exposure to the reactant in process 128 may be carried out at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the silane reactant at a pressure ranging from 10 Torr to 50 Torr and at a temperature ranging from 400°C to 550°C.

[0047] In process 130, the processing chamber is optionally purged after exposure to the reactants. Purging the processing chamber in process 130 can be the same process as the purging described in other embodiments or a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted silane reactants, reaction products, and by-products from the areas adjacent to the substrate surface.

[0048] The thickness of the deposited film or the number of cycles of the molybdenum precursor and the silane reactant is considered in decision 132. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 120 moves to operation 134. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 120 returns to deposition 122 and continues by again exposing the substrate surface to the molybdenum precursor in operation 124.

[0049] In one or more embodiments, after deposition 122 is completed, method 120 includes immersing the substrate in a solution of a titanium precursor in treatment 134. In some embodiments, the titanium precursor may comprise a titanium halide selected from one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), and titanium bromide (TiBr). In particular embodiments, the titanium precursor comprises titanium chloride (TiCl). In some embodiments, the substrate may be immersed in the titanium precursor for a time period ranging from greater than 0 seconds to 60 seconds. In some embodiments, the substrate may be immersed in the titanium precursor at a pressure ranging from 3 Torr to 50 Torr and at a temperature ranging from 300° C. to 500° C.

[0050] In operation 136, the substrate surface or processing chamber may optionally be purged of the titanium precursor. The purging may be the same as or different from the purging described in other embodiments.

[0051] After immersing the substrate in the titanium precursor (operation 134) and optionally purging the substrate surface (operation 136), the method 120 continues with a bulk molybdenum gap-fill operation 138. The bulk molybdenum gap-fill operation 138 may comprise any suitable gap-fill process known to those skilled in the art. In some embodiments, the gap-fill operation comprises exposing the substrate to a molybdenum precursor and a reactant, such as hydrogen (H), to form a bulk molybdenum film. In some embodiments, the molybdenum precursor may be the same molybdenum precursor used to form the nucleation layer. In other embodiments, the molybdenum precursor is different. The molybdenum precursor may be any suitable molybdenum-containing compound capable of reacting with (in other words, adsorbing or chemisorbing onto) the substrate surface to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl), molybdenum fluoride (MoF), molybdenum iodide (MoI), molybdenum bromide (MoBr), molybdenum hexacarbonyl (Mo(CO)), molybdenum dioxide dichloride (MoOCl), molybdenum oxytetrachloride (MoOCl), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In some embodiments, the gap filling process of operation 138 can be a bottom-up gap filling. In other embodiments, the gap filling process can be a traditional gap filling process.

[0052] In one or more embodiments, after the gap fill process, the substrate is annealed in operation 140. Annealing may comprise any suitable annealing process known to those skilled in the art. In one or more embodiments, annealing is performed in an atmosphere of nitrogen (N), helium (He), argon (Ar), or hydrogen (H) gas at a temperature ranging from 600° C. to 1200° C.

[0053] 3, one or more alternative embodiments of the present disclosure are directed to a method of depositing a film 150. The method illustrated in FIG. 3 also represents an atomic layer deposition (ALD) process.

[0054] Method 150 begins at deposition 152, in which a process is performed to deposit a molybdenum-containing film on a substrate (or substrate surface). The deposition process can include one or more treatments to form a film on the substrate. In treatment 154, the substrate (or substrate surface) is exposed to a molybdenum precursor to deposit a film on the substrate (or substrate surface). The molybdenum precursor can be any suitable molybdenum-containing compound that can react with (in other words, adsorb or chemisorb onto) the substrate surface to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dichloride dioxide (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In certain embodiments, the molybdenum precursor comprises molybdenum dichloride dioxide (MoOCl2).

[0055] In operation 156, the processing chamber or the substrate surface is optionally purged to remove unreacted molybdenum precursor, reaction products, and by-products. Purging the processing chamber in operation 156 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0056] In process 158, the substrate (or substrate surface) is exposed to a silane reactant to form a molybdenum silicide film on the substrate. In some embodiments, the molybdenum silicide film is a nucleation film. The silane reactant may comprise any suitable silane reactant known to those skilled in the art. In some embodiments, the silane reactant is selected from the group consisting of silane, disilane, trisilane, tetrasilane, higher silanes, and substituted silanes. The silane reactant can react with molybdenum-containing species on the substrate surface to form a molybdenum silicide film. Exposure to the reactant in process 158 may occur at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the silane reactant at a pressure ranging from 10 Torr to 50 Torr and at a temperature ranging from 400° C. to 550° C.

[0057] In operation 160, the processing chamber is optionally purged after exposure to the reactants. Purging the processing chamber in operation 160 can be the same process as the purging described in other embodiments or a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted silane reactants, reaction products, and by-products from the areas adjacent to the substrate surface.

[0058] In operation 162, the substrate is immersed in a solution of a titanium precursor. In some embodiments, the titanium precursor may comprise a titanium halide selected from one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), and titanium bromide (TiBr). In particular embodiments, the titanium precursor comprises titanium chloride (TiCl). In some embodiments, the substrate may be immersed in the titanium precursor for a time period ranging from greater than 0 seconds to 60 seconds. In some embodiments, the substrate may be immersed in the titanium precursor at a pressure ranging from 3 Torr to 50 Torr and at a temperature ranging from 300°C to 600°C, or from 400°C to 550°C.

[0059] In operation 164, the substrate surface or processing chamber may optionally be purged of titanium chloride. The purging may be the same as or different from the purging described in other embodiments.

[0060] The thickness of the deposited film or the number of cycles of immersion in the molybdenum precursor, silane reactant, and titanium precursor is considered in decision 166. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 150 moves to operation 168. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 150 returns to deposition 152 and continues by again exposing the substrate surface to the molybdenum precursor in operation 154.

[0061] When the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, the method 150 moves to a bulk molybdenum gap fill process 168. The bulk molybdenum gap fill process 168 may comprise any suitable gap fill process known to those skilled in the art. In some embodiments, the gap fill process may be a bottom-up gap fill. In other embodiments, the gap fill process may be a traditional gap fill process.

[0062] In one or more embodiments, after the gap fill process, the substrate is annealed in operation 170. Annealing may comprise any suitable annealing process known to those skilled in the art. In one or more embodiments, annealing is performed in an atmosphere of nitrogen (N), helium (He), argon (Ar), or hydrogen (H) gas at a temperature ranging from 600° C. to 1200° C.

[0063] 4 illustrates a process flow diagram of a method 200 according to one or more embodiments. In the embodiment illustrated in FIG. 4, a substrate may be processed in two atomic layer deposition cycles. In some embodiments, a substrate may be processed in a first deposition cycle 202 followed by a second deposition cycle 214. In other embodiments, a substrate may be processed in a second deposition cycle 214 followed by the first deposition cycle 202. In still further embodiments, a substrate may be processed in a super deposition cycle comprising the first deposition cycle 202 and the second deposition cycle 214.

[0064] The first deposition cycle 202 represents an atomic layer deposition (ALD) process, in which the process is performed to deposit a titanium-containing film on a substrate (or substrate surface). The deposition process can include one or more treatments to form a film on the substrate. In treatment 204, the substrate (or substrate surface) is exposed to a titanium precursor to form titanium species on the substrate (or substrate surface). The titanium precursor can comprise any suitable precursor known to those skilled in the art. In some embodiments, the titanium precursor can comprise one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), titanium bromide (TiBr), and tetrakis(dimethylamino)titanium (TDMAT). In certain embodiments, the titanium precursor comprises titanium chloride (TiCl). In some embodiments, the substrate is exposed to the titanium precursor at a temperature ranging from 200° C. to 600° C. or from 200° C. to 550° C.

[0065] In operation 206, the processing chamber or the substrate surface is optionally purged to remove unreacted titanium precursor, reaction products, and by-products. Purging the processing chamber in operation 206 can be the same process as the purging described in other embodiments or a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, the area adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0066] In operation 208, the substrate (or substrate surface) is exposed to a nitrogen-containing reactant to form a titanium nitride film on the substrate. The nitrogen-containing reactant can be any suitable nitrogen-containing reactant known to those skilled in the art. In one or more embodiments, the nitrogen-containing reactant is selected from one or more of ammonia (NH) or hydrazine (NH).

[0067] In process 210, the processing chamber or substrate surface is optionally purged to remove unreacted nitrogen-containing reactants, reaction products, and by-products. Purging the processing chamber in process 210 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0068] The thickness of the deposited titanium nitride film or the number of cycles of titanium precursor and nitrogen-containing reactant is considered in decision 212. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 200 moves to operation 226. If the deposited film thickness or number of process cycles has not reached a predetermined threshold, method 200 returns to deposition 202 and continues by again exposing the substrate surface to the titanium precursor in operation 204.

[0069] In some embodiments, at decision 212, the method 200 moves to a second deposition cycle 214.

[0070] The second deposition cycle 214 represents an atomic layer deposition (ALD) process, in which the process is performed to deposit a molybdenum-containing film on a substrate (or substrate surface). The deposition process can include one or more treatments to form a film on the substrate. In treatment 216, the substrate (or substrate surface) is exposed to a molybdenum precursor to deposit a film on the substrate (or substrate surface). The molybdenum precursor can be any suitable molybdenum-containing compound that can react with the substrate surface (in other words, adsorb or chemisorb onto the substrate surface) to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dioxide dichloride (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In some embodiments, the substrate (or substrate surface) is exposed to the molybdenum precursor at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400°C to 550°C.

[0071] In operation 218, the processing chamber or the substrate surface is optionally purged to remove unreacted molybdenum precursor, reaction products, and by-products. Purging the processing chamber in operation 218 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0072] In process 220, the substrate (or substrate surface) is exposed to a silane reactant to form a molybdenum silicide film on the substrate. In some embodiments, the molybdenum silicide film is a nucleation film. The silane reactant may comprise any suitable silane reactant known to those skilled in the art. In some embodiments, the silane reactant is selected from the group consisting of silane, disilane, trisilane, tetrasilane, higher silanes, and substituted silanes. The silane reactant may react with molybdenum-containing species on the substrate surface to form a molybdenum silicide film. Exposure to the silane reactant in process 220 may be performed at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the silane reactant at a pressure ranging from 10 Torr to 50 Torr and at a temperature ranging from 400°C to 550°C.

[0073] In operation 222, the processing chamber is optionally purged after exposure to the silane reactant. Purging the processing chamber in operation 222 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted silane reactant, reaction products, and by-products from the area adjacent to the substrate surface.

[0074] The thickness of the deposited film or the number of cycles of the molybdenum precursor and the silane reactant is considered in decision 224. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 200 proceeds to operation 226. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 200 returns to deposition 214 and continues by again exposing the substrate surface to the molybdenum precursor in operation 216.

[0075] In embodiments where the second deposition cycle 214 is performed first, the method 200 may move to the first deposition cycle 202 at decision 224. In one or more embodiments, after the desired thicknesses of the titanium nitride and molybdenum silicide films are obtained, the method 200 moves to a bulk molybdenum gap-fill process 226. The bulk molybdenum gap-fill process 226 may comprise any suitable gap-fill process known to those skilled in the art. In some embodiments, the gap-fill process comprises exposing the substrate to a molybdenum precursor and a reactant, such as hydrogen (H), to form a bulk molybdenum film. The molybdenum precursor may be any suitable molybdenum-containing compound capable of reacting with (in other words, adsorbing or chemisorbing onto) the substrate surface to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dioxide dichloride (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In some embodiments, the substrate (or substrate surface) is exposed to the molybdenum precursor at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400°C to 550°C.

[0076] In one or more embodiments, after the gap fill process, the substrate is annealed in operation 228. Annealing may comprise any suitable annealing process known to those skilled in the art. In one or more embodiments, annealing is performed in an atmosphere of nitrogen (N), helium (He), argon (Ar), or hydrogen (H) gas at a temperature ranging from 600° C. to 1200° C.

[0077] 5 illustrates a process flow diagram of a method 300 according to one or more embodiments. In the embodiment illustrated in FIG. 5, a substrate may be processed in two atomic layer deposition cycles. In some embodiments, a substrate may be processed in a first deposition cycle 302 followed by a second deposition cycle 318.

[0078] The first deposition cycle 302 represents an atomic layer deposition (ALD) process, where the process is performed to deposit a titanium-containing film on a substrate (or substrate surface). The deposition process may include one or more treatments to form a film on the substrate. In operation 304, the substrate (or substrate surface) is exposed to a titanium precursor to form titanium species on the substrate (or substrate surface). The titanium precursor may comprise any suitable precursor known to those skilled in the art. In some embodiments, the titanium precursor may comprise one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), titanium bromide (TiBr), and tetrakis(dimethylamino)titanium (TDMAT). In certain embodiments, the titanium precursor comprises titanium chloride (TiCl). In some embodiments, the substrate is exposed to the titanium precursor at a temperature within a range from 200° C. to 600° C. or from 200° C. to 550° C.

[0079] In operation 306, the processing chamber or substrate surface is optionally purged to remove unreacted titanium chloride, reaction products, and by-products. Purging the processing chamber in operation 306 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0080] In operation 308, the substrate (or substrate surface) is exposed to a nitrogen-containing reactant to form a titanium nitride film on the substrate. The nitrogen-containing reactant can be any suitable nitrogen-containing reactant known to those skilled in the art. In one or more embodiments, the nitrogen-containing reactant is selected from one or more of ammonia (NH) or hydrazine (NH).

[0081] In operation 310, the processing chamber or substrate surface is optionally purged to remove unreacted nitrogen-containing reactants, reaction products, and by-products. Purging the processing chamber in operation 210 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0082] The thickness of the deposited titanium nitride film or the number of cycles of titanium precursor and nitrogen-containing reactant is considered in decision 312. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 300 moves to operation 314. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 300 returns to deposition 302 and continues by again exposing the substrate surface to the titanium precursor in operation 304.

[0083] In operation 314, the substrate having the titanium nitride film thereon is immersed in a solution of a titanium precursor, for example, titanium chloride (TiCl). The titanium precursor may comprise any suitable titanium precursor known to those skilled in the art. In some embodiments, the titanium precursor may comprise a titanium halide selected from one or more of titanium chloride (TiCl), titanium fluoride (TiF), titanium iodide (TiI), and titanium bromide (TiBr). In certain embodiments, the titanium precursor comprises titanium chloride (TiCl). In some embodiments, the substrate may be immersed in the titanium precursor for a time period ranging from greater than 0 seconds to 60 seconds. In some embodiments, the substrate may be immersed in the titanium precursor at a pressure ranging from 3 Torr to 50 Torr and at a temperature ranging from 300°C to 600°C, or from 400°C to 550°C.

[0084] In operation 316, the substrate surface or processing chamber may optionally be purged of the titanium precursor. The purging may be the same as or different from the purging described in other embodiments.

[0085] In one or more embodiments, after the titanium precursor immersion in process 314, the method 300 moves to a second deposition cycle 318.

[0086] The second deposition cycle 318 represents an atomic layer deposition (ALD) process, in which the process is performed to deposit a molybdenum-containing film on a substrate (or substrate surface). The deposition process may include one or more treatments to form a film on the substrate. In operation 320, the substrate (or substrate surface) is exposed to a molybdenum precursor to deposit a film on the substrate (or substrate surface). The molybdenum precursor may be any suitable molybdenum-containing compound that can react with the substrate surface (in other words, adsorb or chemisorb onto the substrate surface) to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl5), molybdenum fluoride (MoF6), molybdenum iodide (MoI6), molybdenum bromide (MoBr3), molybdenum hexacarbonyl (Mo(CO)6), molybdenum dioxide dichloride (MoOCl2), molybdenum oxytetrachloride (MoOCl4), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. In some embodiments, the substrate (or substrate surface) is exposed to the molybdenum precursor at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400°C to 550°C.

[0087] In operation 322, the processing chamber or the substrate surface is optionally purged to remove unreacted molybdenum precursor, reaction products, and by-products. Purging the processing chamber in operation 322 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted reactants, reaction products, and by-products from the area adjacent to the substrate surface.

[0088] In operation 324, the substrate (or substrate surface) is exposed to a silane reactant to form a molybdenum silicide film on the substrate. In some embodiments, the molybdenum silicide film is a nucleation film. The silane reactant may comprise any suitable silane reactant known to those skilled in the art. In some embodiments, the silane reactant is selected from the group consisting of silane, disilane, trisilane, tetrasilane, higher silanes, and substituted silanes. The silane reactant can react with molybdenum-containing species on the substrate surface to form a molybdenum silicide film. The exposure to the silane reactant in operation 324 may be performed at any suitable temperature, pressure, and exposure duration known to those skilled in the art. In some embodiments, the substrate (or substrate surface) is exposed to the silane reactant at a pressure in the range of 10 Torr to 50 Torr and at a temperature in the range of 400° C. to 550° C.

[0089] In operation 326, the processing chamber is optionally purged after exposure to the silane reactant. Purging the processing chamber in operation 326 can be the same process as the purging described in other embodiments or can be a different process than the purging described in other embodiments. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes unreacted silane reactant, reaction products, and by-products from the area adjacent to the substrate surface.

[0090] The thickness of the deposited film or the number of cycles of the molybdenum precursor and the silane reactant is considered in decision 328. If the deposited film reaches a predetermined thickness or a predetermined number of process cycles have been performed, method 300 proceeds to operation 330. If the deposited film thickness or the number of process cycles has not reached a predetermined threshold, method 300 returns to deposition 318 and continues by again exposing the substrate surface to the molybdenum precursor in operation 320.

[0091] In one or more embodiments, after the desired thickness / number of cycles of the titanium nitride film, titanium precursor soak, and molybdenum silicide film are obtained, method 300 moves to bulk molybdenum gap-fill process 330. In process 330, the substrate (or substrate surface) is exposed to a molybdenum precursor, such as molybdenum dioxide dichloride (MoOCl), followed by exposure to a reactant, i.e., hydrogen (H), to deposit a film on the substrate (or substrate surface). The molybdenum precursor can be any suitable molybdenum-containing compound that can react with (in other words, adsorb or chemisorb onto) the substrate surface to leave molybdenum-containing species on the substrate surface. In one or more embodiments, the molybdenum precursor comprises one or more of molybdenum chloride (MoCl), molybdenum fluoride (MoF), molybdenum iodide (MoI), molybdenum bromide (MoBr), molybdenum hexacarbonyl (Mo(CO)), molybdenum dioxide dichloride (MoOCl), molybdenum oxytetrachloride (MoOCl), tetrakis(dimethylamino)molybdenum(IV), and bis(tert-butylimido)-bis(dimethylamido)molybdenum. The bulk molybdenum gap filling process 330 may comprise any suitable gap filling process known to those skilled in the art. In some embodiments, the gap filling process may be a bottom-up gap filling process. In other embodiments, the gap filling process may be a traditional gap filling process.

[0092] In one or more embodiments, after the gap fill process, the substrate is annealed in operation 332. Annealing may comprise any suitable annealing process known to those skilled in the art. In one or more embodiments, annealing is performed in an atmosphere of nitrogen (N), helium (He), argon (Ar), or hydrogen (H) gas at a temperature ranging from 600° C. to 1200° C.

[0093] 6-11 are cross-sectional views illustrating a memory device 600 at various stages in processing for forming buried word lines (bWLs) according to one or more embodiments.

[0094] Referring to FIG. 6 , a substrate 602 having a plurality of trenches 604 therein is provided. The trenches 604 form recessed channels. The trenches have a bottom 606 and at least one sidewall 608. The plurality of trenches 604 can be formed to have widths within a range of about 10 to about 100 nm, including, but not limited to, a range of about 10 nm to about 80 nm, about 10 nm to about 70 nm, about 10 nm to about 60 nm, about 10 nm to about 50 nm, or about 10 nm to about 40 nm. As will be appreciated by those skilled in the art, the width of the plurality of trenches 604 is defined by the distance W1 from one sidewall 608 to another sidewall 608. The plurality of trenches 604 may be formed to have a depth within a range of about 120 nm to about 250 nm, including, but not limited to, a range of about 120 nm to about 150 nm, about 150 nm to about 200 nm, about 200 nm to about 250 nm, about 120 nm to about 200 nm, or about 150 nm to about 250 nm. As will be appreciated by those skilled in the art, the depth of the plurality of trenches 604 is defined by the distance D1 from the substrate surface 603 to the bottom 606 of the plurality of trenches 604.

[0095] A buffer insulating layer (e.g., a silicon oxide layer, not shown) may be formed on the substrate surface 603, and / or a hard mask layer (e.g., a nitride layer, not shown) may be formed to form the plurality of trenches 604. Such techniques are well known to those skilled in the art and are therefore not shown.

[0096] 7, a gate oxide layer 610 is conformally deposited on the substrate 602, on the substrate surface 603, and along the sidewalls 608 and bottoms 606 of the plurality of trenches 604. In one or more embodiments, the gate oxide layer 610 comprises one or more of silicon oxynitride (SiON), silicon oxide, or a high-k dielectric material.

[0097] While the term "silicon oxide" may be used to describe gate oxide layer 610, those skilled in the art will recognize that the present disclosure is not limited to a particular stoichiometry. For example, the terms "silicon oxide" and "silicon dioxide" may both be used to describe a material having silicon atoms and oxygen atoms in any suitable stoichiometric ratio. The same applies to other materials listed in this disclosure, such as, for example, silicon nitride, silicon oxynitride, tungsten oxide, zirconium oxide, aluminum oxide, hafnium oxide, etc.

[0098] In one or more embodiments, the term "high-k dielectric" refers to a material having a high dielectric constant (e.g., compared to silicon dioxide). In one or more embodiments, the high-k dielectric material is selected from one or more of hafnium oxide (HfO), zirconium oxide (ZrO), vanadium oxide (VO), titanium oxide (TiO), tin oxide (SnO), aluminum oxide (AlO), zinc oxide (ZnO), hafnium silicon oxide (HfSiO), or zirconium silicon oxide (ZrSiO).

[0099] In one or more embodiments, the gate oxide layer 610 has a thickness in the range of about 1 nm to about 7 nm, including about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, or about 7 nm.

[0100] 8, in some embodiments, a work function metal layer 612 is formed on the gate oxide layer 610. As used herein, the term "work function" refers to the bulk chemical potential of a material (e.g., a metal) relative to a vacuum level. In one or more embodiments, the work function metal layer has a work function greater than or equal to 4.3 eV. In some embodiments, the work function metal layer 612 has a work function greater than or equal to 4.5 eV. In other embodiments, the work function metal layer 612 has a work function greater than or equal to 4.3 eV, including greater than or equal to 4.4 eV, greater than or equal to 4.5 eV, greater than or equal to 4.6 eV, greater than or equal to 4.7 eV, greater than or equal to 4.8 eV, greater than or equal to 4.8 eV, greater than or equal to 4.9 eV, greater than or equal to 5.0 eV, greater than or equal to 5.1 eV, or greater than or equal to 5.2 eV.

[0101] In one or more embodiments, the work function metal layer 612 comprises a metal nitride. In one or more embodiments, the work function metal layer 612 comprises one or more of titanium nitride (TiN), tungsten nitride (WN), tantalum nitride (TaN), molybdenum nitride (MoN), TaN / TiN, or WN / TiN. In one or more embodiments, the work function metal layer 612 is selected from the group consisting of titanium nitride (TiN), tungsten nitride (WN), tantalum nitride (TaN), molybdenum nitride (MoN), TaN / TiN, WN / TiN, and combinations thereof. In one or more embodiments, the work function metal layer 612 comprises titanium nitride.

[0102] In one or more embodiments, the work function metal layer 612 has a thickness in the range of about 1 nm to about 5 nm, including about 1 nm, about 2 nm, about 3 nm, about 4 nm, or about 5 nm.

[0103] 9, a metal layer 614 is formed over the gate oxide layer 610 and in the plurality of trenches 604. In one or more embodiments, the metal layer 614 is formed by depositing a molybdenum-containing nucleation layer 613 (e.g., molybdenum silicide) followed by a bulk molybdenum gap fill according to one or more embodiment methods illustrated in FIGS.

[0104] In some embodiments, the thickness T1 of the metal layer 614 is controlled. In some embodiments, the thickness T1 of the metal layer 614 is controlled relative to the depth D1 of the plurality of trenches 604. In some embodiments, the thickness T1 is greater than or equal to about 90% of the depth D1 of the plurality of trenches 604. Referring to FIG. 10 , in some embodiments, the thickness T1 of the metal layer 614 exceeds the depth D1 of the trenches 604, and an overburden of the metal layer 614 may be formed on the substrate.

[0105] In some embodiments, annealing of the substrate is performed. Without intending to be bound by theory, it is believed that forming the nucleation layer 613 by the method of one or more embodiments advantageously provides no line bending of the metal layer 614 in the plurality of trenches 604. Additionally, forming the nucleation layer 613 results in little delamination of the metal layer 614 upon annealing and substantially no void formation, particularly substantially no voids at the interface between the substrate and the metal layer 614. As used in this regard, a material that is substantially free of seams or voids has gaps, seams, or voids occupying less than 2%, less than 1%, or less than 0.5% of the volume of the stated material.

[0106] Referring to FIG. 11 , in some embodiments, the metal layer 614 is recessed (embedded) by chemical mechanical polishing (CMP) and etch-back so that the metal layer 614 and the work function metal layer 612 do not protrude beyond the substrate surface 603 (e.g., so that the metal layer 614 is fully embedded within the substrate 602).

[0107] In one or more embodiments, buried word lines 615 (i.e., recessed metal layer 614) may be formed. In some embodiments, as illustrated in Figure 11, the work function metal layer 612 is recessed to the same level as the buried word lines 615. The top surfaces 617 of the buried word lines 615 and work function metal layer 612 have a recess depth or distance D2 from the substrate surface 603 in the plurality of trenches 604.

[0108] After the formation of wordlines 615, processing of the substrate may continue to form memory devices. Such processes are known by those skilled in the art.

[0109] The present disclosure will now be described with reference to the following examples. Before describing several example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. [Example]

[0110] Example 1 A silicon substrate with a trench was placed in a processing chamber and immersed in a titanium chloride (TiCl4) solution for 600 seconds. The processing chamber was purged for 10 seconds. Molybdenum dichloride dioxide was flowed into the processing chamber in a nitrogen (N2) gas atmosphere over the immersed silicon substrate, leaving a molybdenum precursor-terminated surface. Unreacted precursors and by-products were then purged from the chamber. Next, silane was introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactants and by-products were removed from the chamber by purging. The molybdenum dichloride and silane process cycle was completed twice. The trench was then gap-filled with a bulk molybdenum film.

[0111] Example 2 A silicon substrate with a trench was placed in a processing chamber. Molybdenum dioxide dichloride was flowed onto the silicon substrate in a nitrogen (N2) gas atmosphere, leaving a molybdenum precursor-terminated surface. Unreacted precursors and by-products were then purged from the chamber. Next, silane was introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactants and by-products were removed from the chamber by purging. The process cycle was repeated twice. The substrate was then immersed in titanium chloride for 300 seconds. Excess titanium chloride was removed from the chamber by purging. The trench was then gap-filled with a bulk molybdenum film.

[0112] Example 3 A silicon substrate with a trench was placed in a processing chamber. Molybdenum dioxide dichloride was flowed onto the silicon substrate in a nitrogen (N2) gas atmosphere, leaving a molybdenum precursor-terminated surface. Unreacted precursors and by-products were then purged from the chamber. Next, silane was introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactants and by-products were removed from the chamber by purging. The substrate was then immersed in titanium chloride. Excess titanium chloride was removed from the chamber by purging. The super process cycle was repeated. The trench was then gap-filled with a bulk molybdenum film.

[0113] Example 4 A silicon substrate with a trench was placed in a processing chamber. Titanium chloride was flowed onto the silicon substrate in an argon (Ar) gas atmosphere. Unreacted titanium chloride was purged from the chamber. Ammonia (NH3) was then introduced into the chamber and reacted with the titanium species on the substrate to form a titanium nitride film. Excess ammonia and by-products were removed from the chamber by purging. Molybdenum dichloride dioxide was then flowed into the processing chamber in a nitrogen (N2) gas atmosphere onto the silicon substrate with the titanium nitride thereon, leaving a molybdenum precursor-terminated surface. Unreacted precursor and by-products were then purged from the chamber. Silane was then introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactant and by-products were removed from the chamber by purging. The molybdenum and silane cycle was repeated twice. The trench was then gap-filled with a bulk molybdenum film.

[0114] Example 5 A silicon substrate with a trench was placed in a processing chamber. Molybdenum dioxide dichloride was then flowed into the processing chamber in a nitrogen (N2) gas atmosphere onto the silicon substrate with the titanium nitride thereon, leaving a molybdenum precursor-terminated surface. Unreacted precursor and by-products were then purged from the chamber. Next, silane was introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactant and by-products were removed from the chamber by purging. The molybdenum and silane cycle was repeated twice. Titanium chloride was flowed onto the substrate in an argon (Ar) gas atmosphere into the processing chamber. Unreacted titanium chloride was purged from the chamber. Next, ammonia (NH3) was introduced into the chamber and reacted with the titanium species on the substrate to form a titanium nitride film. Excess ammonia and by-products were removed from the chamber by purging. The trench was then gap-filled with a bulk molybdenum film.

[0115] Example 6 A silicon substrate with a trench was placed in a processing chamber. Molybdenum dioxide dichloride was then flowed into the processing chamber in a nitrogen (N2) gas atmosphere onto the silicon substrate with the titanium nitride thereon, leaving a molybdenum precursor-terminated surface. Unreacted precursor and by-products were then purged from the chamber. Next, silane was introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactant and by-products were removed from the chamber by purging. Titanium chloride was flowed into the processing chamber in an argon (Ar) gas atmosphere onto the substrate. Unreacted titanium chloride was purged from the chamber. Next, ammonia (NH3) was introduced into the chamber and reacted with the titanium species on the substrate to form a titanium nitride film. Excess ammonia and by-products were removed from the chamber by purging. The super cycle was then repeated. The trench was then gap-filled with a bulk molybdenum film.

[0116] Example 7 A silicon substrate with a trench was placed in a processing chamber. Titanium chloride was flowed onto the silicon substrate in an argon (Ar) gas atmosphere. Unreacted titanium chloride was purged from the chamber. Ammonia (NH) was then introduced into the chamber and reacted with the titanium species on the substrate to form a titanium nitride film. Excess ammonia and by-products were removed from the chamber by purging. The substrate was then immersed in titanium chloride for 10 seconds. The titanium chloride was purged from the reaction chamber. Molybdenum dichloride dioxide was then flowed onto the substrate in a nitrogen (N) gas atmosphere, leaving a molybdenum precursor-terminated surface. Unreacted precursor and by-products were then purged from the chamber. Silane was then introduced into the chamber and reacted with the surface-bound molybdenum species to form a molybdenum silicide film. Again, excess co-reactant and by-products were removed from the chamber by purging. The molybdenum and silane cycle was repeated twice. The trench was then gap filled with a bulk molybdenum film.

[0117] Spatially relative terms, such as "beneath," "below," "lower," "above," and "upper," may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as depicted in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device during use or processing in addition to the orientation depicted in the figures. For example, if a device in the figures were turned over, elements described as "below" or "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an upper and lower orientation. A device may be oriented differently (rotated 90 degrees or at another orientation), and the spatially relative descriptors used herein may be interpreted accordingly.

[0118] The use of the terms "a," "an," and "the" and similar referents in the context of describing the materials and methods discussed herein (particularly in the context of the claims below) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples or illustrative language (e.g., "etc.") provided herein is intended merely to better clarify the materials and methods and does not impose a limitation on the scope unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0119] References throughout this specification to "one embodiment," "some embodiments," "one or more embodiments," or "embodiments" mean that a particular feature, structure, material, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of phrases such as "in one or more embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment of the present disclosure. In one or more embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner.

[0120] Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and apparatus without departing from the spirit and scope of the disclosure. It is hereby intended that the disclosure cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. 1. A method of forming a film, comprising: forming a molybdenum silicide film in a first process cycle comprising sequentially exposing a substrate to a molybdenum precursor, a purge gas, a silane precursor, and a purge gas, the substrate including a plurality of trenches having a gate oxide layer conformally deposited thereon, the molybdenum silicide film being formed on the gate oxide layer at the bottom of the plurality of trenches; forming an immersed substrate having titanium species thereon in a second process cycle, the second process cycle comprising immersing the substrate in a titanium precursor and purging unreacted titanium precursor from the immersed substrate, the immersed substrate being formed before the first process cycle or after the first process cycle; and exposing the substrate to a second molybdenum precursor and reactant after the first process cycle and the second process cycle to fill the plurality of trenches with a bulk molybdenum film; A method comprising:

2. The method of claim 1 , wherein purging comprises one or more of applying a vacuum or flowing a purge gas over the substrate.

3. 10. The method of claim 1, further comprising annealing the substrate, wherein the bulk molybdenum film has line bending of less than 2 nm, is free of delamination of the bulk molybdenum film, and is void-free.

4. 1. A method of forming a film, comprising: forming a titanium nitride film in a first process cycle, the first process cycle comprising exposing a substrate to a first titanium precursor and exposing the substrate to a nitrogen-containing reactant, the substrate including a plurality of trenches having a gate oxide film conformally deposited thereon; forming an immersed substrate having titanium species thereon in a second process cycle, the second process cycle comprising immersing the substrate in a first titanium precursor and purging unreacted first titanium precursor from the immersed substrate; forming a molybdenum silicide film in a third process cycle including sequentially exposing the substrate to a molybdenum precursor, a purge gas, a silane reactant, and a purge gas, the molybdenum silicide film being formed on the gate oxide at the bottom of the plurality of trenches, the first process cycle being performed first, followed by the second process cycle, followed by the third process cycle; and exposing the substrate to a second molybdenum precursor and reactant to fill the plurality of trenches with a bulk molybdenum film after the first process cycle, the second process cycle, and the third process cycle; A method comprising:

5. 5. The method of claim 4, further comprising repeating the third process cycle to fill the plurality of trenches.

6. 6. The method of claim 5, further comprising annealing the substrate, wherein the molybdenum silicide film is substantially void-free.

7. 1. A method of forming a memory device, comprising: Conformally depositing a gate oxide layer on a substrate having a plurality of trenches therein, each trench having a surface, at least one sidewall, and a bottom, the gate oxide layer being formed on the surface, along the at least one sidewall, and on the bottom of the trench; forming a work function metal layer comprising titanium nitride over the gate oxide layer by exposing the substrate to a first titanium precursor and a nitrogen-containing reactant; forming an immersed substrate having titanium species thereon in a process cycle, the process cycle comprising immersing the substrate in a second titanium precursor and purging unreacted second titanium precursor from the immersed substrate, the immersed substrate being formed after forming the work function metal layer; exposing the substrate to a first molybdenum precursor and a silane reactant to form a molybdenum silicide nucleation layer on the immersed substrate; exposing the substrate to a second molybdenum precursor and a reactant to fill the plurality of trenches with a bulk molybdenum film on the molybdenum silicide nucleation layer; annealing the substrate, wherein the bulk molybdenum film has line bending of less than 2 nm, is free of delamination of the bulk molybdenum film, and is void-free; and recessing the annealed bulk molybdenum film to form buried word lines; A method comprising:

8. The method of claim 7 , wherein the substrate is exposed sequentially to the first molybdenum precursor and the silane reactant.

9. 8. The method of claim 7, wherein the second titanium precursor is purged from the surface of the substrate prior to exposing the substrate to the first molybdenum precursor.

10. The method of claim 9 , wherein purging comprises one or more of applying a vacuum or flowing a purge gas over the substrate.

11. The purge gas is nitrogen (N ２ 11. The method of claim 10, wherein the gas comprises one or more of: helium (He), and argon (Ar).

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