Method for processing a titanium nitride film

Abstract

Various embodiments herein relate to methods of forming a titanium nitride film suitable as an overall fill material for electrically conductive features, such as capacitor electrodes and / or buried word lines in a dynamic random access memory (DRAM) device. In one embodiment, a method of forming an electrically conductive feature in a semiconductor device is provided. The method includes thermally treating at least a portion of a substrate surface comprising a titanium nitride layer in the presence of hydrogen radicals. Thermally treating the substrate includes positioning the substrate in a processing volume of a processing chamber, heating the substrate to a processing temperature greater than about 250 °C, generating hydrogen radicals using a remote plasma source fluidly coupled to the processing volume, and maintaining the substrate at the processing temperature while exposing at least a portion of the titanium nitride layer to the generated hydrogen radicals. Here, the substrate includes a field surface having a plurality of openings formed therein, and the at least a portion of the titanium nitride layer is disposed in the plurality of openings.

Description

[0001] background

[0002] field

[0003] The various embodiments described herein generally relate to the manufacture of electronic devices, and more particularly to methods for forming titanium nitride filler materials for use as conductive feature structures in semiconductor devices, such as embedded word lines in dynamic random access memory devices.

[0004] Related technical descriptions

[0005] Tungsten (W) is commonly used as a filler material to form many of the conductive features of semiconductor devices. For example, tungsten is frequently used to form low-resistivity electrical connections within dielectric layers, namely, horizontally arranged metal interconnects, vertical through-vias connecting horizontally arranged metal interconnects between adjacent dielectric layers, and contacts between metal layers and devices formed on or within a substrate beneath the metal layers. Due to its low resistivity, tungsten is also commonly used to form bit lines and word lines, which are used to address individual memory cells in the memory cell array of a dynamic random-access memory (DRAM) device.

[0006] Typically, tungsten conductive feature structures are formed by etching openings (e.g., holes or trenches) in a material layer, lining the openings with a conductive barrier material, and depositing a tungsten layer to fill the lining openings and form the conductive feature structure. Titanium nitride (TiN) is commonly used as a conductive barrier material or "barrier metal" to lining openings due to its ability to prevent the diffusion of tungsten filler material into the surrounding material layer and to promote adhesion between the tungsten filler material and the walls of the lining opening.

[0007] Unfortunately, the reliable production of tungsten feature structures has become increasingly problematic as circuit density increases and device feature structures continue to shrink to meet the demands of next-generation semiconductor devices. Issues such as poor step coverage of titanium nitride layers in openings and voids within deposited tungsten filler materials are amplified as feature structure sizes decrease and can adversely affect device performance or reliability and / or render the device inoperable.

[0008] Therefore, there is a need in the art for improved monolithic filler materials and methods for forming monolithic filler materials for forming conductive feature structures in semiconductor devices. Summary of the Invention

[0009] Several embodiments of this document relate to methods for forming titanium nitride films as integral filler materials suitable for use as conductive feature structures in semiconductor devices, such as capacitor electrodes and / or embedded word lines in dynamic random access memory (DRAM) devices.

[0010] In one embodiment, a method for forming a conductive feature structure in an electronic device is provided. The method includes heat-treating a substrate surface comprising at least a portion of a titanium nitride layer in the presence of hydrogen radicals. The heat-treating of the substrate includes: positioning the substrate in a processing space of a processing chamber; heating the substrate to a processing temperature greater than about 250°C; generating hydrogen radicals using a remote plasma source fluidly coupled to the processing space; and maintaining the substrate at the processing temperature while exposing at least a portion of the titanium nitride layer to the generated hydrogen radicals. Here, the substrate includes a field surface in which a plurality of openings are formed, and at least a portion of the titanium nitride layer is disposed in the plurality of openings.

[0011] In another embodiment, a method of forming a memory device includes heat-treating a titanium nitride layer in the presence of hydrogen radicals. The heat-treating of the titanium nitride layer includes: positioning a substrate in a processing space of a first processing chamber; heating the substrate to a processing temperature greater than about 250°C; generating hydrogen radicals using a remote plasma source fluidly coupled to the processing space; and maintaining the substrate at the processing temperature while exposing the titanium nitride layer to the generated hydrogen radicals. The substrate is characterized by a field surface in which a plurality of openings are formed, and at least a portion of the titanium nitride layer is disposed in the plurality of openings. Here, at least a portion of the titanium nitride layer disposed in the plurality of openings forms embedded word lines of the memory device.

[0012] In another embodiment, a method for forming embedded word lines in a memory device is provided. The method includes (a) positioning a substrate in a first processing space of a first processing chamber, wherein the substrate may include a field surface having a plurality of openings formed therein; (b) depositing a titanium nitride layer on the field surface of the substrate to at least partially fill the plurality of openings; (c) positioning the substrate in a second processing space of a second processing chamber connected to the first processing chamber; (d) heating the substrate to a processing temperature greater than about 250°C; and (e) exposing the titanium nitride layer to hydrogen radicals generated using a remote plasma source fluidly coupled to the second processing space. Attached Figure Description

[0013] To gain a more detailed understanding of the features and structures described above in this disclosure, a more specific description of the disclosure, which has been briefly summarized above, can be obtained by referring to several embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate several typical embodiments of this disclosure and are not intended to limit the scope of this disclosure, as this disclosure allows for several other equivalent embodiments.

[0014] Figure 1A and Figure 1B This is a schematic cross-sectional view of an exemplary processing chamber that can be used to perform the methods described herein.

[0015] Figure 2 This is a schematic plan view of a multi-chamber processing system that can be used to perform the methods described in this paper.

[0016] Figure 3 This is a diagram illustrating a method for forming a conductive feature structure of an electronic device according to one embodiment.

[0017] Figures 4A to 4F It is shown Figure 3 A schematic cross-sectional view of a semiconductor substrate for the method.

[0018] Figures 5A to 5C , Figures 6A to 6D , Figures 7A to 7D ,and Figure 8 The various material properties of titanium nitride (TiN) layers formed using the methods described herein are illustrated graphically.

[0019] For ease of understanding, the same reference numerals have been used to identify common elements in the figures where possible. It is contemplated that elements and features of one embodiment may be advantageously incorporated into several other embodiments without further description. Detailed Implementation

[0020] Several embodiments of this document relate to methods for forming titanium nitride films suitable as integral filler materials for use as conductive feature structures in semiconductor devices, such as capacitor electrodes and / or embedded word lines in dynamic random access memory (DRAM) devices. Titanium nitride is a ceramic material with sufficient conductivity to provide low-ohmic contacts between metallic feature structures and / or metal-semiconductor junctions, and serves as a barrier material to prevent reactions and interdiffusion between the corresponding materials of the metallic feature structures and / or metal-semiconductor junctions. Therefore, titanium nitride is considered a “barrier metal” when used as a relatively thin barrier layer or liner for conductive metals.

[0021] Typically, although relatively thin titanium nitride layers exhibit metallic electrical behavior, the resistivity of conventionally formed titanium nitride layers is excessively high for materials used as bulk-fill conductive materials in most semiconductor device applications. Therefore, several embodiments of this paper provide hydrogen radical-assisted thermal treatment of titanium nitride films to desirously reduce the resistivity of the titanium nitride layers. Advantageously, in addition to reducing the resistivity of the deposited titanium nitride layers, the methods of this paper remove undesirable impurities from the titanium nitride layers, resulting in increased device performance and improved device reliability and yield.

[0022] Figure 1A An exemplary heat treatment system for use in performing aspects of the methods described herein is schematically illustrated in a processing chamber 100. Here, the processing chamber 100 is characterized by: a chamber body 102 defining a processing space 104; a substrate support assembly 106 disposed within the processing space 104; a remote plasma source (RPS) 108 fluidly coupled to the processing space 104; and a system controller 110. The processing space 104 is fluidly coupled to a vacuum source, such as one or more dedicated vacuum pumps, which maintains the processing space 104 at sub-atmospheric conditions and evacuates processing and other gases from the processing space 104. The substrate support assembly 106 includes a substrate support 107 disposed on a support shaft 112, which extends hermetically through a base of the chamber body 102, surrounded, for example, by a bellows (not shown) in a region above or below the chamber base. In this document, the substrate support 107 includes a heater 114, such as a resistance heating element, which is used to heat the substrate support 107 and the substrate 116 disposed on the substrate support 107 to a desired processing temperature.

[0023] RPS 108 is fluidly coupled to hydrogen source 118 and used to generate hydrogen radicals, which then flow through conduit 120, which is fluidly coupled between RPS 108 and processing space 104, into processing space 104. In some embodiments, conduit 120 is characterized by a dielectric liner 122, which, for example, is a quartz liner or an alumina liner, disposed within conduit 120. The dielectric liner 122 advantageously reduces the recombination of radical substances that might otherwise occur between RPS 108 and processing space 104.

[0024] Generally, plasma excitation of hydrogen gas to form neutral hydrogen radicals also generates charged hydrogen ions, which can be accelerated toward the substrate 116 and cause undesirable damage to the characteristic structures formed on the surface of the substrate 116. Therefore, in some embodiments, the processing chamber 100 further includes an ion filter 124 disposed between the RPS 108 and the substrate support 107. The ion filter 124 is used to remove hydrogen ions from the effluent of the RPS 108. Examples of suitable ion filters that can be used with the processing chamber 100 include electrostatic filters, wire or mesh filters, plates with a relatively wide-to-depth ratio opening (e.g., >2:1), or magnetic ion filters. In several embodiments herein, the ion filter 124 removes substantially all of the generated ionic radicals from the RPS effluent before the effluent reaches the processing space 104. As used herein, “substantially all of the generated hydrogen ions” means about 95% or more of the hydrogen ions generated by the RPS 108.

[0025] Operation of the processing chamber 100 is facilitated by a system controller 110. The system controller 110 includes a programmable central processing unit, here a CPU 126, which operates in conjunction with memory 128 (e.g., non-volatile memory) and support circuitry 130. The CPU 126 is one of any form of general-purpose computer processor used in an industrial environment, such as a programmable logic controller (PLC), for controlling the various chamber components and subprocessors. The memory 128 coupled to the CPU 126 is non-transitory and takes the form of a computer-readable storage medium containing instructions (e.g., non-volatile memory) that, when executed by the CPU 126, facilitates the operation of the processing chamber. The support circuitry 130 is conventionally coupled to the CPU 126 and includes caches, clock circuitry, input / output subsystems, power supplies, and similar circuitry, and combinations thereof, coupled to the various components of the processing chamber 100, to facilitate control of the substrate processing operations here.

[0026] Here, the instructions in memory 128 are in the form of a program product, such as a program that implements the methods of this disclosure. In one instance, this disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program of the program product defines the functionality of various embodiments (including the methods described herein). Therefore, a computer-readable storage medium is a variety of embodiments of this disclosure when it carries computer-readable instructions that direct the functionality of the methods described herein. In some embodiments, processing chamber 100 may include Figure 1B Any or a combination of the characteristic structures of the processing system 150 described herein.

[0027] Figure 1B This is a schematic cross-sectional view of a processing system 150 according to one embodiment, which can be used to perform the methods described herein. Here, the processing system 150 is characterized by serial processing chambers 151A-B, which have a chamber cover 152 commonly defining a first chamber space 155A and a second chamber space 155B, one or more chamber walls 153, and a chamber base 154. Each of the processing chambers 151A-B is constructed substantially similarly to facilitate the simultaneous processing of multiple substrates (not shown) under the same or substantially similar processing conditions. One or both of the processing chambers 151A-B may include... Figure 1A Any or a combination of the characteristic structures of the processing chamber 100 described herein. In other embodiments, the construction of the processing chambers 151A-B (e.g., one or more characteristic structures and their components) differs from one another.

[0028] Each of the chamber spaces 155A-B has a corresponding substrate support assembly 156 and a processing sleeve 157 disposed in each of the chamber spaces 155A-B. The processing sleeve includes one or more shielding elements or gaskets for shielding the processing components from the chamber spaces 155A-B and guiding gas flow within the chamber spaces 155A-B. The chamber spaces 155A-B are fluidly coupled to a common vacuum source 158, such as one or more dedicated vacuum pumps, for maintaining the chamber spaces 155A-B at sub-atmospheric conditions and extracting processing and other gases from the chamber spaces 155A-B. Processing gases are delivered to the chamber spaces 155A-B respectively using a common gas delivery system 159.

[0029] Here, each substrate support assembly 156 includes a support shaft 160 movably disposed through the chamber base 154, and a substrate support 161 disposed on the support shaft 160. Typically, the substrate support 161 includes a heater 162, such as a resistance heating element, for heating the substrate and maintaining it at a desired processing temperature. When the substrate support 161 is in the raised position, the chamber cover 152, the substrate support 161, and the shield and gasket of the corresponding processing sleeve 157 together define the corresponding processing spaces 163A-B.

[0030] As shown, each of the processing spaces 163A-B is fluidly coupled to a corresponding remote plasma source (RPS) 164 using a gas conduit 165 disposed between the processing spaces 163A-B. Each RPS 164 is fluidly coupled to one or more gas sources 166A-B of a gas delivery system 159 that supplies processing and other gases to the RPS 164. In some embodiments, each of the gas conduits 165 includes a dielectric liner (not shown), such as... Figure 1AThe dielectric pad 122 described herein, and the processing system 150 further includes one or more ion filters 167 disposed between each RPS 164 and a substrate support 161 disposed in processing spaces 163A-B. The ion filters 167 may be the same as or substantially similar to... Figure 1A The ion filter 124 is described in the text. In several other embodiments, a single remote plasma source can be used to deliver activated material to each of the processing spaces 163A-B.

[0031] The operation of the processing system is facilitated by a system controller 170, which includes a CPU 171, a memory 172, and support circuitry 173, such as... Figure 1A The system controller 110 is generally constructed and includes instructions in memory 172 for implementing the methods described herein.

[0032] Figure 2 This is a top-down cross-sectional view schematically illustrating a multi-chamber processing system 200 according to one embodiment, which can be used to perform the methods described herein. Here, the multi-chamber processing system 200 includes one or more loading locking chambers 202 for receiving a substrate, a transfer chamber 204, and a plurality of processing systems 150A-C, here a first processing system 150A, a second processing system 150B, and an optional third processing system 150C. Each of the processing systems 150A-C is fluidly coupled to each other via a transfer chamber 204 disposed between each of the processing systems 150A-C. The first processing system 150A is configured to perform the hydrogen radical processing method described herein and may be the same as or substantially similar to... Figure 1B The processing system 150 is described herein. The second processing system 150B includes one or more deposition chambers suitable for depositing titanium nitride, such as any one of a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, or a physical vapor deposition (PVD) chamber. An optional third processing system 150C is configured as an etching system to remove an overburden of titanium nitride from the field surface of a substrate, or as a deposition system to deposit a dielectric material (e.g., silicon oxide or silicon nitride). The transfer chamber 204 includes a substrate transporter 206 to facilitate the transfer of substrates between processing systems 150A-C. Here, the transfer chamber 204 is maintained under vacuum so that substrates can be transferred between processing systems 150A-C to perform various aspects of the methods described herein without exposing the substrates to atmospheric conditions.

[0033] Figure 3 This is a diagram illustrating a method for forming a conductive feature structure of a semiconductor device according to one embodiment. Figures 4A to 4F Various aspects of method 300 are shown. Figure 4A It is a schematic isometric view of a portion of a substrate on which a partially fabricated dynamic random access memory (DRAM) device is formed. Figures 4B to 4F The illustration schematically shows embedded word lines (bWL) formed on a DRAM device. Figure 4B It is intercepted along line 4B-4B. Figure 4A The cross-sectional view. It can be anticipated that method 300 or various aspects of method 300 can be performed using the processing chamber 100 and / or the multi-chamber processing system 200 described above, but other suitable chambers may be used.

[0034] Typically, substrate 400 is formed of a semiconductor material (such as silicon, polysilicon, or germanium silicon) and includes a plurality of shallow trench isolation (STI) regions 402 formed in substrate 400 to define a plurality of spaced-apart and electrically isolated active regions 404. STI regions 402 are formed of a dielectric material (such as silicon oxide) and are used to electrically isolate the active regions 404 from each other and thus prevent current leakage between the active regions 404.

[0035] In a partially manufactured DRAM device, multiple openings (here, word line trenches 406) are formed in the field surface 407 of the substrate 400. Each of the multiple word line trenches 406 extends through multiple portions of the STI region 402 and through multiple portions of the active region 404 to separate the source / drain doped regions 408 disposed on opposite sides of the active region 404. Figure 4B Here, the source / drain doped regions 408 are formed by distributing N-type or P-type dopants into multiple portions of the active regions 404 of the substrate 400. Typically, after forming buried word line trenches 406 in the exposed portions of the active regions 404, the exposed portions of the active regions 404 are oxidized to provide a thin layer of dielectric material, such as silicon oxide 410 on the exposed portions of the active regions 404.

[0036] At activity 302, method 300 optionally includes depositing a titanium nitride (TiN) layer 412 onto field surface 407 to fill or at least partially fill a plurality of openings, such as a plurality of word line trenches 406. TiN layer 412 ( Figure 4CAny suitable deposition process can be used, such as chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD). For example, in one embodiment, the CVD process includes reacting a titanium precursor (such as TiCl4) and a nitrogen precursor (such as N2 or NH3) at the surface of the substrate. In another embodiment, the ALD process includes alternately and repeatedly exposing the surface of the substrate to a titanium precursor (such as TiCl4) or a carbon-containing organic titanium precursor, and a nitrogen precursor, such as N2 or NH3.

[0037] Typically, one or both of the CVD or ALD processes can be plasma-enhanced, wherein the method includes forming one or both of the precursors with plasma to form the free radical material of the precursors and exposing the substrate to the plasma and / or the free radical material formed by the plasma. The plasma can be in-situ (formed in the processing space) or can be formed remotely from the substrate, for example, by using a remote plasma source. In several other embodiments, one or both of the CVD or ALD processes are thermal processes, for example, wherein the substrate is heated to promote a reaction at the substrate surface.

[0038] In some embodiments, the TiN layer 412 is deposited using a plasma-enhanced PVD process, in which plasma-excited material from sputtering gas is used to bombard a titanium target and titanium atoms are sputtered from the target. The titanium atoms are then deposited on the substrate surface in the presence of a nitrogen precursor (such as N2) to form the TiN layer 412. Here, the TiN layer 412 is deposited on the field surface 407 to a sufficient thickness to fill openings, such as word line trenches formed in the field surface. In some embodiments, the TiN layer 412 is deposited on a substrate disposed in a processing chamber of a multi-chamber processing system before the substrate is transferred to a different processing chamber for hydrogen radical thermal treatment. In some embodiments, both the deposition of the TiN layer 412 and the hydrogen radical thermal treatment of the TiN layer 412 are performed in the same processing chamber.

[0039] At activity 304, method 300 includes positioning a TiN layer 412 ( ) within the processing space of the processing chamber and depositing it thereon. Figure 4C The substrate 400. Here, the processing space is maintained under vacuum conditions, such as less than atmospheric pressure, such as less than about 500 Torr, less than about 400 Torr, less than about 300 Torr, less than about 200 Torr, less than about 100 Torr, or less than about 50 Torr. In some embodiments, the processing space is maintained at a pressure between about 10 mTorr and about 50 Torr, such as between about 1 mTorr and about 10 mTorr.

[0040] At activity 306, method 300 includes heating and maintaining substrate 400 at a processing temperature of about 200°C or higher, such as 250°C or higher, about 300°C or higher, about 350°C or higher, about 400°C or higher, or about 425°C or higher. In some embodiments, the heat treatment temperature is in the range of about 200°C to about 600°C, such as from about 250°C to about 600°C, from about 250°C to about 500°C, from about 250°C to about 500°C, for example, about 300°C, or from about 350°C to about 550°C, such as from about 400°C to about 500°C, for example, about 450°C. In some embodiments, the processing temperature is less than about 1000°C, such as less than about 900°C, less than about 800°C, less than about 700°C, or less than about 600°C.

[0041] At activity 308, method 300 includes exposing a heated substrate 400 to hydrogen radicals 413. Here, the hydrogen radicals 413 are formed by flowing hydrogen gas (H2) into a remote plasma source (RPS) fluidly coupled to the processing space and igniting and sustaining the hydrogen plasma to form hydrogen radical material 413. The hydrogen radicals 413 then flow into the processing space, and the surface of the TiN layer 412 of the heated substrate 400 is exposed to these hydrogen radicals. Typically, the flow rate of hydrogen gas (H2) to the RPS for processing a 300 mm diameter substrate is between about 10 sccm and about 5000 sccm, such as between about 100 sccm and about 1500 sccm. Appropriate scaling can be used for substrates of different sizes. In several other embodiments, the remote plasma may be formed in a portion of the processing space of a processing chamber separate from the portion of the processing space in which the substrate is disposed. For example, in these embodiments, the remote plasma may be formed in a portion of the processing space separated from the substrate processing portion by a nozzle.

[0042] Typically, before hydrogen radicals reach the processing space and the substrate surface within it, the effluent from the RPS flows through an ion filter to substantially remove all ions from the effluent. In several embodiments in which the remote plasma is formed in a separation section of the processing space, a nozzle positioned between the remote plasma and the substrate processing section can serve as an ion filter.

[0043] Here, activities 306 and 308 are performed simultaneously, such that the substrate is maintained at a desired processing temperature, and the TiN layer 412 disposed on the substrate is simultaneously exposed to hydrogen radicals 413 for a desired processing time. As discussed below, the sheet resistance of the TiN layer 412 formed according to method 300 is expected to decrease with increasing processing temperature and processing time. In some embodiments, the processing time here is the amount of time for maintaining the substrate 400 at the processing temperature while the TiN layer 412 is simultaneously exposed to hydrogen radicals from RPS, such processing time is about 20 seconds or longer, such as about 30 seconds or longer, about 40 seconds or longer, about 50 seconds or longer, about 1 minute or longer, about 1.5 minutes or longer, about 2 minutes or longer, about 2.5 minutes or longer, about 3 minutes or longer, about 3.5 minutes or longer, about 4 minutes or longer, about 4.5 minutes or longer, for example, about 5 minutes or longer.

[0044] At activity 310, method 300 optionally includes a thermal bake process, comprising maintaining the substrate at or near the processing temperature in the presence of hydrogen. Here, the thermal bake process includes maintaining the substrate 400 at the processing temperature or heating the substrate 400 to a second temperature different from the processing temperature while allowing hydrogen to flow into the processing space. Typically, allowing hydrogen to flow into the processing space includes extinguishing the plasma formed in the RPS while continuing to allow hydrogen to flow into its processing space. At activity 310, the hydrogen may flow at approximately the same flow rate as during hydrogen radical treatment activities 306 and 308, or may increase or decrease relative to that flow rate. Activity 310 of method 300 may be performed in the same processing chamber as activities 306 and 308. In several other embodiments, the substrate 400 may be transferred under vacuum to a second processing chamber of a multi-chamber processing system, and the thermal bake process may be performed in the second processing chamber. In some embodiments, the second temperature at activity 310 is about 1.10X or greater than the processing temperatures at 306 and 308, such as about 1.2X or greater, about 1.3X or greater, about 1.4X or greater, about 1.5X or greater, about 1.6X or greater, about 1.7X or greater, about 1.8X or greater, about 1.9X or greater, or about 2X or greater. In other embodiments, the second temperature is about 1.1X or less than the processing temperatures at 306 and 308, such as about 1.2X or less, about 1.3X or less, about 1.4X or less, about 1.5X or less, about 1.6X or less, about 1.7X or less, about 1.8X or less, about 1.9X or less, or about 2X or less.

[0045] Here, after the TiN layer 412 has been deposited to a thickness sufficient to fill the openings (e.g., word line trenches 406) formed in the field surface 407, such as Figure 4CAs shown, activities 306, 308 and optionally 310 are performed. In several other embodiments, the openings can be filled by alternatingly depositing a relatively thin titanium nitride layer 414 (illustrated in dashed lines) in a first processing chamber and heat-treating the relatively thin titanium nitride layer 414 in the presence of hydrogen radicals until the accumulated thin titanium nitride layer fills the plurality of openings to at least the level of the field surface.

[0046] Typically, once the opening is filled, the TiN capping layer 416 is removed from the field surface 407, for example, by a chemical mechanical polishing (CMP) process or an etching-back process, such as... Figure 4D As shown. In some embodiments, such as DRAM manufacturing processes, an etch-back process is used to remove the TiN capping layer 416 from the field surface 407 to form a plurality of buried word lines 418 comprising titanium nitride and / or substantially composed of titanium nitride, such as Figure 4E As shown. Typically, in these embodiments, the embedded word lines 418 are recessed from the field surface 407 to ensure electrical isolation from each other and / or from other conductive features adjacent to the embedded word lines 418. Subsequently, the dielectric layer 420 ( Figure 4F A word line 418 is deposited on the field surface 407 to electrically isolate it and provide further protection for the word line 418, for example, to prevent exposure to atmospheric conditions. In some embodiments, the hydrogen radical thermal treatment method and the etch-back process are each in a multi-chamber processing system (e.g., Figure 2 The process is performed in different processing chambers of the multi-chamber processing system 200. In some embodiments, hydrogen radical thermal treatment is performed on the TiN layer 412 / embedded word line 418 after the capping layer 416 has been removed from the field surface, i.e., after CMP or etch-back processes.

[0047] Advantageously, the hydrogen radical heat treatment method provided above promotes titanium nitride grain growth, produces desired crystallographic orientation at the titanium nitride surface, and removes undesirable impurities from titanium nitride to improve (reduce) the resistivity of the conductive feature structure.

[0048] It is believed that heat-treated hydrogen radicals promote grain growth (increasing the size of crystallites in the material) in the deposited titanium nitride film by diffusing into the film to reduce the activation energy barrier required for grain boundary mobility. The resulting larger grain (crystalloid) size leads to a reduced percentage (volume fraction) of grain boundary area in the titanium nitride layer. This reduced percentage of grain boundary area results in reduced electron scattering at the grain boundary surface and a corresponding decrease in the effective resistance of the conductive feature structures formed therefrom.

[0049] In addition to promoting grain growth, it has been found that the methods described herein desiccate grain feeding during the grain growth stage, but the resulting texture depends at least in part on the type of substrate used and the method of depositing the TiN layer on the substrate. In some embodiments, the treated TiN layer comprises textured surfaces with (111) and (222) crystal orientations for further (desirably) reducing the resistivity of the resulting film.

[0050] In addition to promoting grain growth and desired crystal orientation in titanium nitride materials, the methods described herein desiccately result in titanium nitride films with fewer impurities compared to the deposited film. Typically, the CVD, ALD, and PVD methods described above introduce undesirable process-induced impurities (such as chlorine or carbon) into the titanium nitride film. Hydrogen radicals from the processing methods react with the impurities to form volatile substances such as HCl and / or CHx, which are subsequently degassed from the titanium nitride film and extracted from the processing space. Advantageously, hydrogen atoms introduced during processing processes that do not form volatile HCl and / or CHx substances are expelled from TiN with increasing grain size because hydrogen atoms occupy fewer grain boundary sites. As shown below, higher processing temperatures result in lower hydrogen concentrations in post-processing of the TiN layer.

[0051] Figures 5A to 5C This graph illustrates the percentage change in resistivity (Rs) of the titanium nitride film after the treatment method described in this paper. Figure 5A In the process, the titanium nitride layer 500a was deposited using an ALD method that alternately exposes the substrate to TiCl4 and NH3. Figure 5B In the process, the titanium nitride layer 500b is deposited using an ALD method that alternately exposes the substrate to an organotitanium compound and a nitrogen precursor. Figure 5C In this process, titanium nitride layer 500c is deposited using a PVD method that sputters titanium from a titanium target onto a substrate set in a nitrogen-rich environment. Each of titanium nitride layers 500a-c is deposited to a thickness of approximately 15 nm.

[0052] Each of the titanium nitride layers 500a-c was heated to and maintained at a temperature between 300°C and 450°C, while being exposed to molecular hydrogen (H2 gas) for 5 minutes (treatment condition 502), to hydrogen free radicals for 1 minute (treatment condition 504), or to hydrogen free radicals for 5 minutes (treatment condition 506). For each of treatment conditions 502, 504, and 506, the treatment space was maintained at a pressure of less than 5 Torr. Here, the decrease in resistivity is characterized by the percentage change in the sheet resistance (Rs) between measurements taken before and after the heat treatment.

[0053] like Figures 5A to 5CAs shown, for heat treatment using only 5 molecules of hydrogen (H2 gas) for a duration (processing condition 502), no significant decrease in resistivity (Rs) was observed for each of the corresponding ALD, CVD, and PVD deposited films 502a-c. Instead, an increase in resistivity was observed, which may be attributed to the formation of TiO2 through atmospheric exposure after the substrate was removed from the processing system. x N y This is caused by the hydrogen radical treatments 504 and 506. The reduction in resistivity (Rs) increases with both treatment temperature and treatment time. Among the different types of films, the largest resistivity reduction was observed in the TiN layer deposited by metal-organic compound ALD (500b) under treatment condition 506, in which the substrate was maintained at approximately 450°C for 5 minutes while being exposed to hydrogen radicals. Under the same treatment conditions, TiCl4 ALD deposited and PVD deposited TiN layers (500a and 500c) exhibited resistivity reductions of 20.8% and 14.6%, respectively. Here, most of the Rs reduction occurs during the early stages of the hydrogen radical process. For example, for a TiN layer 500a deposited in TiCl4, maintaining the substrate at approximately 450°C for 1 minute while exposing it to hydrogen radicals (processing condition 504) resulted in a 17.0% decrease in resistivity, while 5 minutes (processing condition 506) resulted in a 20.8% decrease in Rs, i.e., a nonlinear resistivity improvement over time.

[0054] Figures 6A to 6B The chlorine concentration distribution 600a and hydrogen concentration distribution 600b of TiN layers deposited by TiCl4 ALD processed according to the method described herein are shown. Here, the method is used with... Figure 5A The TiCl4 ALD TiN layer was deposited under the same processing conditions as the TiCl4 ALD deposited TiN layer. Figures 6C to 6D The carbon concentration distribution (600c) and hydrogen concentration distribution (600d) of the TiN layer deposited by metal-organic compound ALD are shown. The metal-organic compound layer is then placed in... Figure 5B Deposited under the same conditions as described Figure 5B Describe the same thickness.

[0055] Here, Figures 6A to 6D The illustration shows the impurity distribution of a deposited film 602 without the treatment described herein. The treatment method 603 includes maintaining the substrate at a temperature of 450°C for 5 minutes while exposing the surface to molecular hydrogen, and the treatment methods 604-606 include maintaining the substrate at respective temperatures of 300°C, 400°C, and 450°C for 5 minutes while exposing the surface of the substrate to hydrogen free radicals.

[0056] For chlorine impurities ( Figure 6AWhen compared to the deposited TiN layer 602, hydrogen radical treatment methods 604-606 illustrate significant chlorine removal in the top 5 nm of the TiN layer. The depth of impurity removal often depends on the quality and conditions of the deposited film. For example, in Figure 6A In the diagrams, hydrogen treatment methods 604-606 illustrate significant chlorine removal from the top 5 nm of the TiN layer compared to the deposited TiN layer 602. For other TiCl-deposited films, significant chlorine removal was observed through substantially the entire treated TiN film; that is, the overall reduction in chlorine impurities across the treated TiN film. No significant chlorine removal was observed for molecular hydrogen treatment method 603. Figure 6C In this process, no significant removal of carbon impurities was observed between the deposited TiN layer 602 and the molecular hydrogen treatment method 603. Figure 6C In the process, hydrogen radical-assisted heat treatment methods 604-606 result in a reduction of carbon at the surface and from the surface inward, with the reduction of increased carbon observed at higher treatment temperatures. When compared with the deposited TiN layer 602, both TiCl4ALD and organometallic ALD TiN layers show a reduction in hydrogen concentration after treatment method 603, with the organometallic ALD TiN layer showing a more significant reduction.

[0057] Here, hydrogen radical treatment 604-606 incorporates hydrogen into the TiN layer deposited by ALD. Figure 6B , Figure 6D In this embodiment, a lower hydrogen concentration is observed at the increased processing temperature of 604-606. In several embodiments where hydrogen incorporation is not desired, method 300 may further include a thermal baking process to remove unwanted hydrogen from the TiN layer, as described above in activity 310.

[0058] Quantitative analysis of areal density based on secondary ion mass spectrometry (SIMS) results for chlorine concentrations (600a) and hydrogen concentrations (600b) in TiN layers deposited by TiCl4 ALD, and for carbon concentrations (600c) and hydrogen concentrations (600d) in processing methods 602-606, were conducted. Figures 7A to 7D The diagram in the middle is shown.

[0059] Figure 8X-ray diffraction analysis of the TiN layers of substrates 803a-e exposed to various processing methods is shown. Peak 801 indicates (111) crystal orientation. Peak 802 indicates (200) crystal orientation. The TiN layer of substrate 803a is not processed and has the lowest intensity at both peaks 801 and 802. The TiN layer of substrate 803b is heated to have the highest intensity at peaks 801 and 802 and is processed by the following rapid thermal annealing process: heating the substrate to and maintaining it at approximately 850°C for one minute in the presence of molecular nitrogen (N2). The TiN layer of substrate 803c has the second highest intensity at peaks 801 and 802 and is processed by the following: heating the substrate to and maintaining it at approximately 550°C for one minute in the presence of hydrogen radicals. The TiN layer of substrate 803d has the third highest intensity peak and is processed by the following: heating the substrate to and maintaining it at approximately 550°C for four minutes in the presence of hydrogen radicals. The TiN layer of substrate 803e has a fourth high intensity peak and is subjected to the following treatment: substrate 803e is heated to and maintained at about 550°C for 1 minute in the presence of molecular hydrogen (H2).

[0060] Although the foregoing relates to various embodiments of this disclosure, various other and further embodiments of this disclosure may be designed without departing from the basic scope of this disclosure, and the scope of this disclosure is defined by the appended claims.

Claims

1. A method for forming a conductive feature structure in an electronic device, comprising the following steps: Heat treatment of at least a portion of the substrate surface containing a titanium nitride layer includes the following steps: The substrate is positioned in the processing space of the first processing chamber, the substrate comprising a field surface having a plurality of openings and at least a portion of the titanium nitride layer disposed in the plurality of openings, the plurality of openings being formed in the field surface; The substrate is heated to a first temperature greater than 250°C; Hydrogen radicals are generated using a remote plasma source fluidly coupled to the processing space; The substrate is maintained at the first temperature while at least a portion of the titanium nitride layer is exposed to the generated hydrogen radicals; and The substrate is maintained at a second temperature different from the first temperature, while hydrogen gas flows into the processing space and extinguishes the plasma formed in the remote plasma source.

2. The method of claim 1, wherein the step of generating the hydrogen radical comprises the following steps: Hydrogen gas (H2) is allowed to flow into the remote plasma source; The plasma that ignites and sustains the hydrogen gas; and The effluent from the remote plasma source is allowed to flow into the processing space, wherein the effluent contains the hydrogen radicals.

3. The method of claim 2, further comprising the step of: removing hydrogen ions from the effluent of the remote plasma source by using an ion filter before allowing the effluent to flow into the processing space.

4. The method of claim 1, wherein the titanium nitride layer is also disposed on the field surface, and the titanium nitride layer fills the plurality of openings to at least the level of the field surface.

5. The method of claim 1, wherein the titanium nitride layer forms a plurality of embedded word lines of the memory device.

6. The method of claim 1, further comprising the step of: depositing the titanium nitride layer in a second processing chamber before transferring the substrate to the first processing chamber, wherein the first processing chamber is connected to the second processing chamber via a transfer chamber disposed between the first processing chamber and the second processing chamber.

7. The method of claim 6, further comprising the steps of: alternately and repeatedly depositing titanium nitride layers in the second processing chamber and exposing the titanium nitride layers to hydrogen radicals in the first processing chamber until the plurality of titanium nitride layers fill the plurality of openings to at least the level of the field surface.

8. A method of forming a memory device, comprising the following steps: The heat treatment of the titanium nitride layer includes the following steps: The substrate is positioned in the processing space of the first processing chamber, the substrate comprising a field surface having a plurality of openings and at least a portion of the titanium nitride layer disposed in the plurality of openings, the plurality of openings being formed in the field surface, wherein the at least portion of the titanium nitride layer forms a plurality of embedded word lines; The substrate is heated to a processing temperature greater than 250°C; Hydrogen radicals are generated using a remote plasma source fluidly coupled to the processing space; and The substrate is maintained at the processing temperature while the titanium nitride layer is exposed to the generated hydrogen radicals; and The substrate is maintained at a second temperature different from the processing temperature, while hydrogen gas flows into the processing space and extinguishes the plasma formed in the remote plasma source.

9. The method of claim 8, wherein the memory device includes source and drain regions disposed on opposite sides of the embedded word lines.

10. The method of claim 8, wherein the step of generating the hydrogen radical comprises the following steps: Hydrogen gas (H2) is allowed to flow into the remote plasma source; The plasma that ignites and sustains the hydrogen gas; and The effluent from the remote plasma source is allowed to flow into the processing space, wherein the effluent contains the hydrogen radicals.

11. The method of claim 10, further comprising the step of: removing generated hydrogen ions from the effluent of the remote plasma source by using an ion filter before allowing the effluent to flow into the processing space.

12. The method of claim 8, wherein the titanium nitride layer is also disposed on the field surface, and wherein the titanium nitride layer fills the plurality of openings to at least the level of the field surface.

13. The method of claim 8, further comprising the step of: depositing the titanium nitride layer in a second processing chamber before transferring the substrate to the first processing chamber, wherein the first processing chamber is connected to the second processing chamber via a transfer chamber disposed between the first processing chamber and the second processing chamber.

14. The method of claim 13, further comprising the steps of: alternately and repeatedly depositing the titanium nitride layer in the second processing chamber and maintaining the substrate at the processing temperature in the first processing chamber while exposing the titanium nitride layer to the generated hydrogen radicals until the plurality of titanium nitride layers fill the plurality of openings to at least the level of the field surface.

15. A method for forming embedded word lines in a memory device, comprising the steps of: (a) Positioning a substrate in a first processing space of a first processing chamber, the substrate including a field surface having a plurality of openings formed in the field surface; (b) Depositing a titanium nitride layer on the field surface of the substrate to at least partially fill the plurality of openings; (c) Positioning the substrate in a second processing space connected to a second processing chamber of the first processing chamber; and (d) Heating the substrate to a processing temperature greater than 250°C; (e) Exposing the titanium nitride layer to hydrogen radicals generated using a remote plasma source fluidly coupled to the second processing space; and (f) The substrate is maintained at a second temperature different from the processing temperature, while hydrogen flows into the processing space and the plasma formed in the remote plasma source is extinguished.

16. The method of claim 15, further comprising the step of sequentially repeating (a)-(e) until the plurality of titanium nitride layers fill the plurality of openings to at least the level of the field surface.

17. The method of claim 15, wherein the step of generating the hydrogen radical comprises the following steps: Hydrogen gas (H2) is allowed to flow into the remote plasma source; The plasma that ignites and sustains the hydrogen gas; and The effluent from the remote plasma source is allowed to flow into the second processing space, wherein the effluent contains the hydrogen radicals.

18. The method of claim 17, further comprising the step of: removing hydrogen ions from the effluent of the remote plasma source by using an ion filter before allowing the effluent to flow into the second processing space.

19. The method of claim 15, wherein the memory device includes source and drain regions disposed on opposite sides of the embedded word lines.

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