Methods for forming low resistivity tungsten features

Abstract

A substrate structure including a tungsten-containing layer is provided, the tungsten-containing layer comprising a nucleation layer and a filler layer. The nucleation layer is disposed along the sidewall of an opening. The nucleation layer comprises boron and tungsten. The filler layer is disposed above the nucleation layer within the opening. The resistivity of the tungsten-containing layer is about 16 μΩ·cm or less. The thickness of the tungsten-containing layer is about 200 angstroms to about 600 angstroms. The thickness of the tungsten-containing layer is half the width of the tungsten-containing layer within the opening between opposite sidewall portions of the opening.

Description

Technical Field

[0001] The embodiments described herein relate to methods for manufacturing electronic devices, and more specifically, to methods for forming tungsten features in semiconductor devices. Prior Technology

[0002] Tungsten (W) is widely used in the manufacture of integrated circuit (IC) devices to form conductive features with relatively low resistance and relatively high resistance to electromigration. For example, tungsten can be used as a metal filler material to form source contacts, drain contacts, metal gate fillers, gate contacts, interconnect structures (e.g., horizontal features formed in the surface of a dielectric material layer), and vias (e.g., vertical features formed through a dielectric material layer to connect other interconnect features disposed on or below it). Due to its relatively low resistivity, tungsten is also frequently used to form bit lines and word lines, which are used to address the individual memory cells in the memory cell array of a dynamic random access memory (DRAM) device.

[0003] As circuit density increases and device features continue to shrink to meet the demands of next-generation semiconductor devices, reliably manufacturing tungsten features has become increasingly challenging. Issues such as voids and seams formed during conventional tungsten deposition processes are amplified as feature sizes decrease, potentially adversely affecting device performance and reliability, or even rendering the device inoperable.

[0004] Therefore, a process is needed to fill contact features that have no or virtually no gaps and seams, and have low resistivity for various film thicknesses. Summary of the Invention

[0005] A structure including a tungsten-containing layer is provided, the tungsten-containing layer comprising a nucleation layer and a filling layer. The nucleation layer is disposed along the sidewall of an opening. The nucleation layer comprises boron and tungsten. The filling layer is disposed above the nucleation layer within the opening. The resistivity of the tungsten-containing layer is about 16 μΩ·cm or less. The thickness of the tungsten-containing layer is about 200 angstroms to about 600 angstroms. The thickness of the tungsten-containing layer is half the width of the tungsten-containing layer within the opening disposed between opposite sidewall portions of the opening.

[0006] A structure on a substrate is provided, the structure including an opening within the substrate. An adhesive layer is disposed on a sidewall of the opening, and a tungsten-containing layer is disposed above the adhesive layer within the sidewall. The resistivity of the tungsten-containing layer is about 16 μΩ·cm or less, and the thickness of the tungsten-containing layer is about 200 angstroms to about 600 angstroms. The thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between opposite sidewall portions of the opening.

[0007] A method for forming a structure is provided. The method includes the steps of: exposing a substrate to a tungsten-containing precursor gas at a precursor gas flow rate; exposing the substrate to a reducing agent comprising boron at a reducing agent flow rate; and cyclically alternating the tungsten-containing precursor gas and the reducing agent to form a nucleation layer over the substrate within at least one opening in the substrate. The method further includes the step of depositing a fill layer over the nucleation layer within the at least one opening. The substrate is annealed at about 600°C to about 1000°C. Simple Explanation of the Diagram

[0008] To gain a more detailed understanding of the features described above, a more detailed description of the present disclosure can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only exemplary embodiments and should not be construed as limiting the scope of such embodiments; other equally effective embodiments are permissible.

[0009] Figures 1A-1B are schematic cross-sectional views of a portion of the substrate, illustrating undesirable voids or seams in conventionally formed tungsten features.

[0010] Figure 2A is a schematic side view of a processing system that can be used to implement the methods described herein, according to one embodiment.

[0011] Figure 2B is a close-up cross-sectional view of a portion of the processing system shown in Figure 2A according to one embodiment.

[0012] Figure 3 is a close-up cross-sectional view of a portion of the processing system shown in Figure 2A according to one embodiment.

[0013] Figure 4 depicts a schematic side view of a rapid heat treatment system that can be used to implement the methods described herein, according to one embodiment.

[0014] Figure 5 is a diagram illustrating a method for processing a substrate according to one embodiment.

[0015] Figure 6A is a schematic cross-sectional side view of a substrate before processing, according to one embodiment.

[0016] Figure 6B is a schematic cross-sectional side view of a substrate during the processing stage according to one embodiment.

[0017] Figure 6C is a schematic cross-sectional side view of a substrate during the processing stage according to one embodiment.

[0018] Figure 7 depicts comparison curves illustrating the resistivity of thin film layers formed using the methods and comparison methods described herein at various film thicknesses, according to some embodiments.

[0019] Figure 8 depicts comparison curves illustrating the resistivity of thin film layers formed using the methods described herein before and after annealing at various temperatures, according to some embodiments.

[0020] Figure 9 depicts comparison curves illustrating the resistivity of thin film layers formed using the methods described herein at various film thicknesses before and after annealing.

[0021] For ease of understanding, the same reference numerals are used where possible to indicate common elements in the figures. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. Implementation

[0022] The embodiments described herein generally relate to the manufacture of electronic devices, and more specifically to systems and methods for forming low resistivity tungsten features in semiconductor device manufacturing schemes.

[0023] Figure 1A is a schematic cross-sectional view of substrate 10A, illustrating the undesirable voids 20 formed during a conventional tungsten deposition process. Here, substrate 10A includes a patterned surface 11 comprising a dielectric layer 12, a barrier material layer 14, and a tungsten layer 15. High aspect ratio openings (shown as being filled by a portion of the tungsten layer 15) are formed in the dielectric layer. The barrier material layer is deposited on the dielectric layer 12 to align along the openings, and the tungsten layer is deposited on the barrier material layer 14. The tungsten layer 15 is formed using a conventional deposition process, such as chemical vapor deposition (CVD) or atomic layer deposition (ALD), in which tungsten is conformally deposited (grown) on the patterned surface 11 to fill the openings. The tungsten layer 15 forms tungsten features 15A in the openings and forms a material capping layer (tungsten capping layer 15B) in the area of ​​the patterned surface 11.

[0024] In Figure 1A, the opening has a non-uniform profile, which is narrower at the surface of substrate 10A and widens (bends outward) as the opening extends inward from the surface into the dielectric layer 12. As shown, the overhanging portions of the conformal tungsten layer 15 have grown together, blocking or "cutting off" the entrance to the opening before it can be completely filled, resulting in undesirable voids 20 in the tungsten feature 15A, i.e., no tungsten material. If voids 20 are opened (exposed) during subsequent CMP processes, polishing fluid may infiltrate the tungsten feature 15A, and the chemically active components of the polishing fluid may cause further loss of tungsten material therein, for example, through corrosion and / or static etching of the tungsten material, resulting in unwanted feature coring (key-holing). This undesirable tungsten loss can lead to performance and reliability issues with the equipment, or ultimately, complete equipment failure. Even without voids, undesirable seams in tungsten features are essentially unavoidable using conventional tungsten deposition processes, as shown in Figure 1B.

[0025] Figure 1B is a schematic cross-sectional view of substrate 10B illustrating an undesirable seam 24 formed during a conventional tungsten deposition process. Here, the patterned surface 11 includes an opening (filled with a portion of the tungsten layer 15) that has a substantially uniform profile as it extends from the surface of substrate 10B into the dielectric layer 12. The opening is filled with tungsten, and no voids are formed. Nevertheless, the tungsten layer 15 grows conformally outward from the walls of the opening, resulting in an undesirable seam 24 extending through the center of the tungsten feature 15A formed in the opening. Similar to the voids 20 shown in Figure 1A, seam 24 is susceptible to corrosion by the chemically active components of the tungsten polishing fluid, which could lead to an undesirable loss of tungsten material from feature 15A if seam 24 is exposed during a CMP process.

[0026] Therefore, embodiments of this document provide a processing system configured to perform a combination of various method states without transferring substrates between processing chambers, thereby improving the overall substrate processing yield and capability of the tungsten gap-filling processing scheme described herein.

[0027] Generally, gap-filling processes involve forming differentiated tungsten deposition suppression profiles in characteristic openings formed in the substrate surface, filling the openings with tungsten material according to the suppression profiles, and depositing a tungsten capping layer on the field surface of the substrate. Forming the tungsten deposition suppression profiles typically involves forming a tungsten nucleation layer and treating the tungsten nucleation layer with active nitrogen species (e.g., treated radicals). Nitrogen treated radicals are incorporated into a portion of the nucleation layer, for example, by adsorbing nitrogen species and / or by reacting with the metallic tungsten of the nucleation layer to form tungsten nitride (WN). The adsorbed nitrogen and / or nitrided surface of the tungsten nucleation layer preferably delays (suppresses) tungsten nucleation, thereby delaying (suppressing) subsequent tungsten deposition thereon.

[0028] In some embodiments, the process radicals are formed at the distal end of the substrate processing chamber using a distal plasma source fluidly coupled to the substrate processing chamber. By controlling the processing conditions (e.g., temperature and pressure) within the processing chamber and controlling the concentration, flux, and energy of the process radicals at the substrate surface, a desired suppression effect on the patterned surface area and a desired suppression profile in the openings formed in the patterned surface are achieved. Typically, the process radicals are formed from non-halogen nitrogen-containing gases, such as N₂, NH₃, NH₄, or combinations thereof.

[0029] Tungsten nucleation and deposition processes in gap-filling solutions typically involve flowing a tungsten-containing precursor and a reducing agent into a processing chamber, exposing the substrate surface therein. The tungsten-containing precursor and reducing agent react on the substrate surface using one of chemical vapor deposition (CVD), pulsed CVD, atomic layer deposition (ALD), or combinations thereof, to deposit tungsten material thereon.

[0030] The processing system described herein is configured to periodically perform chamber cleaning operations in which unwanted tungsten residues are removed from the internal surfaces of the processing chamber using cleaning chemicals (e.g., cleaning chemicals that include active halogen species, such as fluorine or chlorine (cleaning) radicals) formed at the distal end of the processing chamber.

[0031] Chamber cleaning operations generally involve introducing halogenated cleaning radicals into the processing chamber, allowing the cleaning radicals to react with tungsten residues to form volatile tungsten species, and then venting the volatile tungsten species from the processing chamber using an exhaust system. Chamber cleaning operations are typically performed between substrate processing steps (i.e., after the treated substrate has been removed from the processing chamber and before the next treated substrate is received into the processing chamber).

[0032] Figures 2A-2B schematically illustrate a processing system 200 that can be used to perform the bottom-up tungsten interstitial filling substrate processing method described herein. Here, the processing system is configured to provide the different processing conditions required for each of the nucleation process, suppression process, selective interstitial filling process, and capping deposition process within a single processing chamber 202, i.e., without the need to transfer the substrate between multiple processing chambers.

[0033] As shown in Figure 2A, the processing system 200 includes a processing chamber 202, a gas delivery system 204 fluidly coupled to the processing chamber 202, and a system controller 208. The processing chamber 202 (shown in cross-section in Figure 2A) includes a chamber cover assembly 210, one or more sidewalls 212, and a chamber base 214, which together define a processing volume 215. The processing volume 215 is fluidly coupled to an exhaust device 217 (e.g., one or more vacuum pumps) for maintaining the processing volume 215 under sub-atmospheric conditions and venting processing gases and processing byproducts therefrom.

[0034] The chamber cover assembly 210 includes a cover plate 216 and a showerhead 218 coupled to the cover plate 216 to define a gas distribution volume 219. Here, the cover plate 216 is maintained at a desired temperature using one or more heaters 229 thermally coupled thereto. The showerhead 218 faces a substrate support assembly 220 disposed in the processing volume 215. As discussed below, the substrate support assembly 220 is configured to move a substrate support 222 between a raised substrate processing position (shown) and a lowered substrate transport position (not shown), thereby moving a substrate 230 disposed on the substrate support 222. When the substrate support assembly 220 is in the raised substrate processing position, the showerhead 218 and the substrate support 222 define a processing area 221.

[0035] The gas delivery system 204 is fluidly coupled to the processing chamber 202 via a gas inlet 223 (FIG. 2B), which is provided by a cover plate 216. Processing or cleaning gas delivered by the gas delivery system 204 flows into the gas distribution volume 219 through the gas inlet 223 and is distributed into the processing area 221 through a plurality of openings 232 (FIG. 2B) in the shower head 218. In some embodiments, the chamber cover assembly 210 further includes a perforated baffle 225 disposed between the gas inlet 223 and the shower head 218. In those embodiments, the gas flowing into the gas distribution volume 219 is first diffused by the baffle 225 to provide a more uniform or desired gas distribution into the processing area 221, together with the shower head 218.

[0036] Processing gases and processing byproducts are vented radially outward from processing zone 221 through an annular channel 226 surrounding processing zone 221. The annular channel 226 may be formed in a first annular liner 227 disposed radially inside the one or more sidewalls 212 (as shown), or it may be formed within the one or more sidewalls 212. In some embodiments, processing chamber 202 includes one or more second liners 228 for protecting the one or more sidewalls 212 or the inner surface of the chamber base 214 from corrosive gases and / or unwanted material deposits.

[0037] In some embodiments, a purge gas source 237, in fluid communication with the processing volume 215, is used to allow a chemically inert purge gas (e.g., argon (Ar)) to flow into a region located beneath the substrate support 222, for example, through an opening in the chamber base 214 surrounding the support shaft 262. During substrate processing, the purge gas can be used to create a positive pressure region beneath the substrate support 222 (compared to the pressure in the processing region 221). Generally, the purge gas introduced through the chamber base 214 flows upward from the chamber base and around the edge of the substrate support 222 to be vented from the processing volume 215 through the annular channel 226. By reducing and / or preventing the inflow of material precursor gases, the purge gas reduces undesirable material deposition on the surface beneath the substrate support 222.

[0038] The substrate support assembly 220 includes a movable support shaft 262 that extends hermetically through a chamber base 214 (e.g., surrounded by a bellows 265 in a region below the chamber base 214) and a substrate support 222 (which is disposed on the movable support shaft 262). To facilitate the transfer of substrates to and from the substrate support 222, the substrate support assembly 220 includes a lifting pin assembly 266 comprising a plurality of lifting pins 267 coupled to or engaged with a lifting pin clamp 268. The plurality of lifting pins 267 are movably disposed in an opening formed through the substrate support 222. When the substrate support 222 is positioned in a lowered substrate transfer position (not shown), the plurality of lifting pins 267 extend above the substrate receiving surface of the substrate support 222 to lift the substrate 230 from there and allow a substrate handler to access the back (non-moving) surface of the substrate 230. When the substrate support 222 is in the raised or processing position (as shown), the plurality of lifting pins 267 retract below the substrate receiving surface of the substrate support 222 to allow the substrate 230 to rest on it.

[0039] The substrate 230 is conveyed to and from the substrate support 222 via a door 271 (e.g., a slit valve disposed in one of the one or more sidewalls 212). Here, one or more openings in the area surrounding the door 271 (e.g., openings in the door housing) are fluidly coupled to a purge gas source 237 (e.g., an Ar gas source). The purge gas is used to prevent the processing gas and cleaning gas from contacting and / or degrading the seals surrounding the door, thereby extending their service life.

[0040] The substrate support 222 is configured for vacuum clamping, wherein the substrate 230 is secured to the substrate support 222 by applying a vacuum to the interface between the substrate 230 and the substrate receiving surface. The vacuum is applied using a vacuum source 272 fluidly coupled to one or more channels or ports formed in the substrate receiving surface of the substrate support 222. In other embodiments, such as when the processing chamber 202 is configured for direct plasma processing, the substrate support 222 may be configured for electrostatic clamping. In some embodiments, the substrate support 222 includes one or more electrodes (not shown) coupled to a bias voltage power supply (not shown), such as a continuous wave (CW) RF power supply or a pulsed RF power supply, which supplies a bias voltage to the one or more electrodes.

[0041] As shown in the figure, the substrate support assembly 220 has a dual-zone temperature control system to provide independent temperature control in different regions of the substrate support 222. The different temperature control zones of the substrate support 222 correspond to different regions of the substrate 230 disposed thereon. Here, the temperature control system includes a first heater 263 and a second heater 264. The first heater 263 is disposed in the central region of the substrate support 222, and the second heater 264 is disposed radially outward of the central region to surround the first heater. In other embodiments, the substrate support 222 may have a single heater or more than two heaters.

[0042] In some embodiments, the substrate support assembly 220 further includes an annular shielding ring 235 for preventing unwanted material deposition on the circumferential beveled edge of the substrate 230. During the transfer of the substrate to and from the substrate support 222, i.e., when the substrate support assembly 220 is in a lowered position (not shown), the shielding ring 235 rests on an annular lug within the processing volume 215. When the substrate support assembly 220 is in an elevated or processing position, the radially outer surface of the substrate support 222 engages with the annular shielding ring 235, such that the shielding ring 235 encloses the substrate 230 disposed on the substrate support 222. Here, the shielding ring 235 is shaped such that, when the substrate support assembly 220 is in the elevated substrate processing position, the radially inward-facing portion of the shielding ring 235 is positioned above the beveled edge of the substrate 230.

[0043] In some embodiments, the substrate support assembly 220 further includes an annular purification ring 236 disposed on the substrate support 222 to enclose the substrate 230. In those embodiments, a shielding ring 235 may be disposed on the purification ring 236 when the substrate support assembly 220 is in an elevated substrate processing position. Generally, the purification ring 236 has a plurality of radially inwardly facing openings that are in fluid communication with a purification gas source 237. During substrate processing, purification gas flows into the annular region defined by the shielding ring 235, the purification ring 236, the substrate support 222, and the beveled edge of the substrate 230 to prevent processing gas from entering the annular region and causing undesirable material deposition on the beveled edge of the substrate 230.

[0044] In some embodiments, the processing chamber 202 is configured for direct plasma processing. In those embodiments, the showerhead 218 may be electrically coupled to a first power supply 231 (e.g., an RF power supply) that supplies power to ignite and sustain the plasma via capacitive coupling with the processing gas flowing into the processing region 221. In some embodiments, the processing chamber 202 includes an inductive plasma generator (not shown), and the plasma is formed by inductively coupling the RF power supply to the processing gas.

[0045] The processing system 200 is advantageously configured to perform each of the tungsten nucleation, suppression treatment, and bulk tungsten deposition processes in a gapless and seamless tungsten gap-filling process scheme without removing the substrate 230 from the processing chamber 202. Gases for performing the various processes of the gap-filling process scheme and gases for cleaning residues from the inner surface of the processing chamber are delivered to the processing chamber 202 using a gas delivery system 204, which is fluidly coupled to the processing chamber.

[0046] Generally, the gas delivery system 204 includes one or more remote plasma sources (here, a first radical generator 206A and a second radical generator 206B), a deposition gas source 240, and a conduit system 294 (e.g., a plurality of conduits 294A-F) that fluidly couples the radical generators 206A-B and the deposition gas source 240 to the cover assembly 210. The gas delivery system 204 further includes a plurality of isolation valves, here a first valve 290A and a second valve 290B, which are respectively disposed between the radical generators 206A-B and the cover plate 216, and can be used to fluidly isolate each of the radical generators 206A-B from the processing chamber 202 and to fluidly isolate these radical generators from each other.

[0047] Each of the radical generators 206A-B has a chamber body 280 that defines a corresponding first plasma chamber volume 281A and a second plasma chamber volume 281B (FIG. 2B). Each of the radical generators 206A-B is coupled to a corresponding power supply 293A-B. The power supply 293A-B is used to ignite and sustain plasmas 282A-B of gases supplied to plasma chamber volumes 281A-B from a corresponding first gas source 287A or second gas source 287B, which are fluidly coupled to the plasma chamber volumes. In some embodiments, the first radical generator 206A generates radicals for a differentiated suppression process. For example, the first radical generator 206A may be used to ignite and sustain a processing plasma 282A from a halogen-free gas mixture supplied from a first gas source 287A to the first plasma chamber volume 281A. The second free radical generator 206B can be used to generate clean free radicals for the chamber cleaning process by igniting and sustaining a clean plasma 282B from a halogen-containing gas mixture delivered from a second gas source 287B to a second plasma chamber volume 281B.

[0048] Generally, nitrogen-treated radicals have a relatively short lifetime (compared to halogen-cleaned radicals) and may exhibit relatively high sensitivity to recombination resulting from collisions with surfaces in the gas delivery system 204 and / or with other species in the treated plasma effluent. Therefore, in the embodiments herein, the first radical generator 206A is typically positioned closer to the gas inlet 223 than the second radical generator 206B to, for example, provide a relatively short travel distance from the first plasma chamber volume 281A to the treatment region 221.

[0049] In some embodiments, the first free radical generator 206A is also fluidly coupled to a second gas source 287B, which supplies a halogen-containing conditioning gas to the first plasma chamber volume 281A for plasma source conditioning. In those embodiments, the gas delivery system 204 may further include a plurality of diversion valves 291 operable to direct the halogen-containing gas mixture from the second gas source 287B to the first plasma chamber volume 281A.

[0050] Suitable distal plasma sources that can be used in one or both of the free radical generators 206A-B include radio frequency (RF) or very high radio frequency (VHRF) capacitively coupled plasma (CCP) sources, inductively coupled plasma (ICP) sources, microwave induced plasma (MW) sources, electron cyclotron acceleration resonance (ECR) chambers, or high-density plasma (HDP) chambers.

[0051] As shown in the figure, the first radical generator 206A is fluidly coupled to the processing chamber 202 via a first conduit 294A and a second conduit 294B, which extend upward from the gas inlet 223 to connect to the outlet of the first plasma chamber volume 281A. A first valve 290A, disposed between the first conduit 294A and the second conduit 294B, is used to selectively fluidly isolate the first radical generator 206A from the processing chamber 202 and other parts of the gas delivery system 204. Typically, the first valve 290A is closed during the chamber cleaning process to prevent activated cleaning gases (e.g., halogen radicals) from flowing into the first plasma chamber volume 281A and damaging its surface.

[0052] By using the third conduit 294C and the fourth conduit 294D, the second free radical generator 206B is fluidly coupled to the second conduit 294B, thereby fluidly coupling to the processing chamber 202. By using the second valve 290B disposed between the third conduit 294C and the fourth conduit 294D, the second free radical generator 206B is selectively isolated from the processing chamber 202 and from other parts of the gas delivery system 204.

[0053] Deposited gas (e.g., containing tungsten precursors and reducing agents) is delivered from deposited gas source 240 to processing chamber 202 via a fifth conduit 294E. As shown, the fifth conduit 294E is coupled to the second conduit 294B near gas inlet 223, such that the first valve 290A and the second valve 290B can be used to isolate the first radical generator 206A and the second radical generator 206B from the deposited gas introduced into processing chamber 202, respectively. In some embodiments, gas delivery system 204 further includes a sixth conduit 294F, which is coupled to the fourth conduit 294D near the second valve 290B. The sixth conduit 294F is fluidly coupled to a bypass gas source 238 (e.g., an argon (Ar) gas source), which can be used to periodically purge unwanted residual cleaning, suppression, and / or deposited gas from a portion of gas delivery system 204.

[0054] The operation of the processing system 200 is facilitated by a system controller 208. The system controller 208 includes a programmable central processing unit (here, CPU 295) that can operate in conjunction with memory 296 (e.g., non-volatile memory) and support circuitry 297. The CPU 295 is one of any form of general-purpose computer processor (e.g., a programmable logic controller (PLC)) used in industrial environments to control various chamber components and subprocessors. The memory 296, coupled to the CPU 295, facilitates the operation of the processing chambers. The support circuitry 297 is conventionally coupled to the CPU 295 and includes cache memory, clock circuitry, input / output subsystems, power supplies, and combinations thereof, which are coupled to various components of the processing system 200 to facilitate processing operations using its control board.

[0055] The instructions in memory 296 are in the form of a program product, such as a program that implements the methods of this disclosure. In one example, this disclosure may be implemented as a program product stored on a computer-readable storage medium for use by a computer system. The program of the program product defines the functionality of the embodiments (including the methods described herein). Therefore, a computer-readable storage medium is an embodiment of this disclosure when it carries computer-readable instructions that direct the functionality of the methods described herein.

[0056] The aforementioned processing system 200 can be used to perform each of nucleation, suppression, and interstitial filling deposition, thereby providing a single-chamber seamless tungsten interstitial filling solution.

[0057] Figure 3 is a close-up cross-sectional view of the deposition gas source 240 of the processing system shown in Figure 2A according to one embodiment. The deposition gas source 240 includes a first gas source 302 (e.g., a reducing agent gas source) and a second gas source 314 (e.g., a tungsten-containing precursor). The reducing agent gas source 302 is in fluid communication with a reservoir 306. The reservoir 306 is continuously filled with the reducing gas source 302 or refilled using a refill valve 304. The pressure of the reservoir 306 is monitored using a pressure gauge 308. It has been found that the reservoir 306 allows for the rapid release of large quantities of gas into the process chamber 202. During operation, such as during pulses, large quantities of gas are released at high reducing gas flow rates (e.g., about 200 sccm or greater, for example, about 300 sccm or greater) to flow into the process chamber 202. The reducing gas is released from the reservoir 306 into the chamber 202 via a valve 310 disposed along a conduit 294E. A second gas source 314 is in fluid communication with chamber 202 via conduit 294E. The second gas source 314 allows the tungsten-containing precursor to flow into chamber 202 via valve 312. One or more of valves 304, 310, and 312 are controlled using a controller (e.g., system controller 208). In some embodiments, depending on operating parameters, one or more of these valves switch between an open and closed state at predetermined time intervals.

[0058] After the substrate is processed in process chamber 202, it is transferred to a second processing system (e.g., substrate processing system 400 depicted in FIG. 4) for annealing. Substrate processing system 400 may be a rapid thermal processing (RTP) apparatus. Substrate processing system 400 includes a heat treatment chamber 402 and a process gas source 404 coupled to the heat treatment chamber 402 and used to supply process gas to a processing region 406 of the heat treatment chamber 402. Processing region 406 is surrounded by one or more sidewalls 408 (e.g., four sidewalls, or a single sidewall of a circular process region 406) and a base 410. The upper portion of the sidewall 408 may be sealed to a window assembly 412 (e.g., using an O-ring for sealing). A radiation energy assembly 414 is positioned above and coupled to the window assembly 412. The radiation energy assembly 414 has a plurality of lamps 416, which may be halogen tungsten lamps, and each is mounted in a socket 418 and positioned to emit electromagnetic radiation into the processing area 406. The window assembly 412 of FIG. 4 has a plurality of light tubes 420, but the window assembly 412 may be a flat, solid window without any light tubes. The window assembly 412 has an outer wall 422 (e.g., a cylindrical outer wall) that forms a rim surrounding the circumference of the window assembly 412. The window assembly 412 also has a first window 424 and a second window 426, the first window covering a first end of the plurality of light tubes 420 and the second window covering a second end of the plurality of light tubes 420 opposite to the first end. The first window 424 and the second window 426 extend to and engage with the outer wall 422 of the window assembly 412 to surround and seal the interior of the window assembly 412, including the plurality of light tubes 420. In this case, when using light tubes, a vacuum can be generated in the plurality of light tubes 420 by applying a vacuum to one of the plurality of light tubes 420 through a conduit 428 passing through the outer wall 422, which is fluidly connected to the other light tubes.

[0059] The substrate W is supported in the heat treatment chamber 402 by a support ring 430 within the processing area 406. The support ring 430 is mounted on a rotatable cylinder 432. By rotating the rotatable cylinder 432, the support ring 430 and the substrate W are rotated during processing. The base 410 of the heat treatment chamber 402 has a reflective surface 434 for reflecting energy to the back side of the base W during processing. Alternatively, a separate reflector (not shown) may be positioned between the base 410 of the heat treatment chamber 402 and the support ring 430. The heat treatment chamber 402 may include a plurality of temperature probes 436 disposed through the base 410 of the heat treatment chamber 402 to detect the temperature of the substrate W. As described above, when using a separate reflector, the temperature probes 436 are also disposed through that separate reflector for optical access to electromagnetic radiation from the substrate W.

[0060] A rotatable cylinder 432 is supported by a magnetic rotor 438, which is a cylindrical member with a lug 440 on which the rotatable cylinder 432 rests when both members are installed in the heat treatment chamber 402. The magnetic rotor 438 has a plurality of magnets in a magnet region 442 below the lug 440. The magnetic rotor 438 is disposed in an annular well 444, which is positioned along the base 410 in the peripheral region of the heat treatment chamber 402. A cover 446 rests on the peripheral portion of the base 410 and extends above the annular well 444 toward the rotatable cylinder 432 and the support ring 430, leaving a tolerance clearance between the cover 446 and the rotatable cylinder 432 and / or the support ring 430. The cover 446 generally protects the magnetic rotor 438 from the process conditions in the processing area 406.

[0061] The magnetic rotor 438 rotates by magnetic energy from a magnetic stator 448 disposed around the base 410. The magnetic stator 448 has a plurality of electromagnets 450, which are powered according to a rotational mode during the processing of the substrate W to form a rotating magnetic field that provides magnetic energy to rotate the magnetic rotor 438. The magnetic stator 448 is coupled to a linear actuator 452 by a support member 454. Operation of the linear actuator 452 moves the magnetic stator 448 along the axis 456 of the heat treatment chamber 402, which in turn moves the magnetic rotor 438, the rotatable cylinder 432, the support ring 430, and the substrate W along the axis 456.

[0062] Processing gas is supplied to the heat treatment chamber 402 through chamber inlet 458 and discharged through chamber outlet facing outward and oriented generally along the same plane as chamber inlet 458 and support ring 430 (not shown in FIG. 4). The substrate enters and exits the heat treatment chamber 402 through inlet / outlet port 460, which is formed in the sidewall 408 and shown at the rear of FIG. 4.

[0063] Although a single gas source 404 is depicted in Figure 4, other gas sources are also considered. Gas source 404 may also be coupled to a plasma initiator (not shown) to remotely supply radicals to the process volume. Gas source 404 may be or include one or more of nitrogen-containing gases, oxygen-containing gases, silicon-containing gases, hydrogen-containing gases, or plasma-forming gases (such as argon or helium).

[0064] Figure 5 is a diagram illustrating a method 500 for processing a substrate according to an embodiment, which can be performed using processing system 200 and processing system 400. Figures 6A-6C are schematic cross-sectional views of a portion of substrate 600, illustrating various aspects of method 500 at different stages of a void-free and seamless tungsten gap filling process.

[0065] The substrate 600 has a patterned surface 601, which includes a dielectric material layer 602 in which a plurality of openings 605 (one shown) are formed. In some embodiments, the plurality of openings 605 include one or a combination of vias or trenches with a high aspect ratio, having a width of about 1 micrometer or less, such as about 800 nanometers or less, or about 500 nanometers or less, and a depth of about 2 micrometers or greater, such as about 3 micrometers or greater, or about 4 micrometers or greater. In some embodiments, the aspect ratio (depth to width ratio) of each opening in the openings 605 can be about 3:1 or greater, such as about 5:1 or greater, or 10:1 or greater. In some embodiments, the vias or trenches are about 20 nanometers to about 50 nanometers in size and have an aspect ratio of about 3:1 to about 10:1.

[0066] As shown, the patterned surface 601 includes a barrier or adhesive layer 603 (e.g., a titanium nitride (TiN) layer) deposited on a dielectric material layer 602 to conformally align along the opening 605 and facilitate subsequent deposition of a tungsten nucleation layer 604. In some embodiments, the adhesive layer 603 is deposited to a thickness between about 20 Å and about 150 Å, for example, about 30 Å to about 100 Å.

[0067] At operation 502, method 500 includes the steps of: exposing a substrate having an adhesive layer 603 to a tungsten-containing precursor gas at a precursor gas flow rate. At operation 504, exposing the substrate to a reducing agent at a reducing agent flow rate. Operations 502 and 504 are used alternately in a cycle, either starting with 502 or starting with 504. In some embodiments, operations 502 and 504 are used alternately in a cycle, starting with operation 502 and ending with operation 504. Operations 502 and 504 are used together in a nucleation process to form a nucleation layer 604 on the substrate. The ratio of the reducing agent gas flow rate to the precursor reducing agent flow rate is about 5:1 or greater, for example, about 6:1 to about 10:1, by volume. A portion of an exemplary substrate 600 on which the nucleation layer 604 is formed is schematically illustrated in Figure 6A.

[0068] In some embodiments, the nucleation layer 604 is deposited using an atomic layer deposition (ALD) process. The ALD process includes repeatedly alternating cycles of exposing the substrate 600 to a tungsten-containing precursor and to a reducing agent. In some embodiments, the process area 221 is cleaned between alternating exposures. In some embodiments, the process area 221 is continuously cleaned during operations 402 and 404. Suitable examples of tungsten-containing precursors include tungsten halides such as tungsten hexafluoride (WF6), tungsten hexachloride (WCl6), or combinations thereof. In some embodiments, the tungsten-containing precursor includes WF6, and the reducing agent includes a boron-containing agent such as B₂H₆. In some embodiments, the tungsten-containing precursor includes organometallic precursors and / or fluorine-free precursors, such as MDNOW (methylcyclopentadienyl-dicarbonyInitrosyl-tungsten), EDNOW (ethylcyclopentadienyl-dicarbonyInitrosyl-tungsten), hexacarbonyltungsten (W(CO)6), or combinations thereof.

[0069] During the nucleation process, the processing volume 215 is maintained at a pressure less than about 120 Torr, for example, between about 900 mTorr and about 120 Torr, between about 1 Torr and about 100 Torr, or for example, between about 1 Torr and about 50 Torr. Exposing the substrate 600 to the tungsten-containing precursor includes flowing the tungsten-containing precursor from the deposition gas source 240 into the processing region 221 at a flow rate of about 100 sccm or less, for example, from about 10 sccm to about 60 sccm, or from about 20 sccm to about 80 sccm. Exposing the substrate 600 to the reducing agent includes flowing the reducing agent from the deposition gas source 240 into the processing region 221 at a flow rate of about 200 sccm to about 1000 sccm, for example, between about 300 sccm and about 750 sccm. It has been found that the gas deposition source 240 described in Figure 3 is particularly designed to cause flow from the reducing gas source 302 via the reservoir 306 at a gas flow rate of about 100 sccm or greater (e.g., about 300 sccm or greater).

[0070] It should be noted that the flow rates of the various deposition and processing processes described herein are for a processing system 200 configured to process substrates with a diameter of 300 mm. Appropriate scaling can be used for processing systems configured to process substrates of different sizes.

[0071] The tungsten-containing precursor and reducing agent each flow into processing zone 221 for a duration between about 0.1 seconds and about 10 seconds, for example, between about 0.5 seconds and about 5 seconds. Between alternating exposures, processing zone 221 can be purified by allowing a purge gas (e.g., argon (Ar) or hydrogen) to flow into processing zone 221 for a duration between about 0.1 seconds and about 10 seconds (e.g., between about 0.5 seconds and about 5 seconds). The purge gas can be supplied from deposition gas source 240 or from bypass gas source 238. Typically, the cycle of repeating the nucleation process continues until the thickness of nucleation layer 404 is between about 10 angstroms and about 200 angstroms, for example, between about 10 angstroms and about 150 angstroms, or between about 20 angstroms and about 150 angstroms. Nucleation layer 604 is disposed along the sidewall of opening 605, for example, above a barrier or adhesive layer 603. The atomic ratio of boron to tungsten in the nucleation layer is about 1:n, where n is about 5 or less, for example about 1:4.5 to about 1:1, for example about 1:4 to about 1:2, or about 1:3 to 3:4, for example about 1.1:1 to about 2:1.

[0072] At operation 506, method 500 includes the steps of: treating nucleation layer 604 to suppress tungsten deposition on the field surface of substrate 600, and forming differential suppression profiles in the plurality of openings 605 by using a differential suppression process. Typically, forming differential suppression profiles involves exposing nucleation layer 604 to an activated species of a process gas, such as process radical 606 as shown in FIG. 6B. Suitable process gases that can be used for the suppression process include N2, H2, NH3, NH4, O2, CH4, or combinations thereof. In some embodiments, the process gas includes nitrogen, such as N2, H2, NH3, NH4, or combinations thereof, and the activated species includes nitrogen radicals, such as atomic nitrogen. In some embodiments, the process gas is combined with an inert carrier gas (e.g., Ar, He, or combinations thereof) to form a process gas mixture.

[0073] Without being bound by theory, it is believed that activated nitrogen species are incorporated into the nucleation layer 604 by adsorbing activated nitrogen species (treated free radical 606) and / or by reacting with metallic tungsten of the nucleation layer 604 to form a tungsten nitride (WN) surface. The adsorbed nitrogen and / or nitride surface of the tungsten nucleation layer 604 preferably delays (inhibits) further tungsten nucleation, thereby delaying (inhibiting) subsequent tungsten deposition thereon.

[0074] In some embodiments, exposing the nucleation layer 604 to the processing radicals 606 includes forming a processing plasma 282A of a substantially halogen-free processing gas mixture using a first radical generator 206A, and allowing the effluent of the processing plasma 282A to flow into the processing region 221. In some embodiments, the flow rate of the process gas mixture flowing into the first free radical generator 206A is between about 1 sccm and about 3000 sccm, for example, between about 1 sccm and about 2500 sccm, between about 1 sccm and about 2000 sccm, between about 1 sccm and about 1000 sccm, between about 1 sccm and about 500 sccm, between about 1 sccm and about 250 sccm, between about 1 sccm and about 100 sccm, or between about 1 sccm and about 75 sccm, for example, between about 1 sccm and about 50 sccm, and so is the flow rate of the process plasma effluent flowing into the processing zone 221.

[0075] In some embodiments, the suppression process includes exposing the substrate 600 to treatment free radicals 606 for a time of about 2 seconds or longer, such as about 4 seconds or longer, about 6 seconds or longer, about 8 seconds or longer, about 9 seconds or longer, about 10 seconds or longer to about 20 seconds.

[0076] In some embodiments, the concentration of the substantially halogen-free process gas in the process gas mixture is from about 0.1 volume percent to about 50 volume percent, for example from about 0.2 volume percent to about 40 volume percent, from about 0.2 volume percent to about 30 volume percent, from about 0.2 volume percent and about 20 volume percent, or for example between about 0.2 volume percent and about 10 volume percent, for example between about 0.2 volume percent and about 5 volume percent.

[0077] In other embodiments, the processed radical 606 may be formed using a distal plasma (not shown) ignited and maintained in a portion of a processing volume 215, which is separated from the processing volume 221 by a showerhead 218, for example, between the showerhead 218 and a cover plate 216. In those embodiments, before the processed radical 606 reaches the processing region 221 and the surface of the substrate 600, the activated processing gas may flow through an ion filter to remove substantially all ions. In some embodiments, the showerhead 218 may serve as an ion filter. In other embodiments, the plasma used to form the processed radical is an in-situ plasma formed in the processing region 221 between the showerhead 218 and the substrate 600. In some embodiments, for example when using an in-situ processing plasma, the substrate 600 may be biased to control the directionality and / or accelerate the ions (e.g., charged processed radicals) formed by the processing gas toward the substrate surface.

[0078] In some embodiments, the suppression process includes maintaining the processing volume 215 at a pressure of less than about 100 Torr while allowing activated processing gas to flow into it. For example, during the suppression process, the processing volume 215 may be maintained at a pressure of less than about 75 Torr, such as less than about 50 Torr, less than about 25 Torr, less than about 15 Torr, or between about 0.5 Torr and about 120 Torr, such as between about 0.5 Torr and about 100 Torr, or between about 0.5 Torr and about 50 Torr, or between about 1 Torr and about 10 Torr.

[0079] At operation 508, method 500 includes the step of depositing tungsten interstitial material 608 (FIG. 6C) into the plurality of openings 605 based on a differentiated suppression profile provided by the suppression process at operation 206. In one embodiment, the tungsten interstitial material 608 is formed using a chemical vapor deposition (CVD) process that includes simultaneously flowing (co-flowing) a tungsten-containing precursor gas and a reducing agent into a processing region 221, exposing a substrate 600 therein. The tungsten-containing precursor and reducing agent used in the tungsten interstitial CVD process may include any combination of tungsten-containing precursors and reducing agents described with reference to operations 502 and 504. In some embodiments, the tungsten-containing precursor includes WF 6, and the reducing agent includes hydrogen.

[0080] A tungsten-containing precursor flows into processing zone 221 at a rate between about 10 sccm and about 1000 sccm, or greater than about 50 sccm, or less than about 1000 sccm, or between about 100 sccm and about 900 sccm. A reducing agent flows into processing zone 221 at a rate greater than about 500 sccm (e.g., greater than about 750 sccm, greater than about 1000 sccm, or between about 500 sccm and about 10000 sccm, such as between about 1000 sccm and about 9000 sccm, or between about 1000 sccm and about 8000 sccm).

[0081] In some embodiments, the tungsten interstitial CVD process conditions are selected to provide a tungsten feature with relatively low residual film stress compared to conventional tungsten CVD processes. For example, in some embodiments, the tungsten interstitial CVD process includes heating the substrate to a temperature of about 250°C or greater, such as about 300°C or greater, or between about 250°C and about 600°C, or between about 300°C and about 500°C. During the CVD process, the processing volume 215 is generally maintained at a pressure of less than about 500 Torr, less than about 600 Torr, less than about 500 Torr, less than about 400 Torr, or between about 1 Torr and about 500 Torr (e.g., between about 1 Torr and about 450 Torr, or between about 1 Torr and about 400 Torr, or for example between about 1 Torr and about 300 Torr).

[0082] In another embodiment, the tungsten interstitial filling material 608 is deposited at operation 508 using an atomic layer deposition (ALD) process. The tungsten interstitial filling ALD process includes repeating the following cycle: alternatingly exposing the substrate 600 to a tungsten-containing precursor gas and a reducing agent, and cleaning the treatment area 221 between alternating exposures.

[0083] The tungsten-containing precursor and reducing agent each flow into processing zone 221 for a duration between about 0.1 seconds and about 10 seconds, for example, between about 0.5 seconds and about 5 seconds. Between alternating exposures, processing zone 221 is typically purged by allowing an inert purge gas (e.g., argon (Ar) or hydrogen) to flow into processing zone 221 for a duration between about 0.1 seconds and about 10 seconds (e.g., between about 0.5 seconds and about 5 seconds). The purge gas can be supplied from deposition gas source 240 or from bypass gas source 238.

[0084] In other embodiments, the tungsten interstitial filling material 608 is deposited using a pulsed CVD method, which involves repeating the following cycle: alternatingly exposing the substrate 600 to a tungsten-containing precursor gas and a reducing agent without purging the treated area 221. The processing conditions for the tungsten interstitial pulsed CVD method may be the same, substantially the same, or within the same range as those described above for the tungsten interstitial ALD process.

[0085] It has been found that forming a nucleation layer 604 with a high boron concentration relative to tungsten can reduce film resistivity and surface roughness of the tungsten-containing layer, while maintaining seamless or substantially seamless gap filling at various thicknesses 620 (e.g., about 2000 angstroms or less, such as about 600 angstroms or less, such as about 200 angstroms to about 600 angstroms). The film thickness 620 is measured as half the width of the tungsten-containing layer (e.g., nucleation layer 604 and tungsten gap-filling material 608) disposed within the opening between opposing sidewall portions of the opening 605. Alternatively, the film thickness 620 is the distance between the centerline of the opening 605 and the interface between the adhesive layer 603 and the nucleation layer 604. In some embodiments, the nucleation layer 604 and the filling layer 608 are monolithic with no interface between them. The tungsten gap-filling material 608 and the nucleation layer 604 together form the tungsten-containing layer, which has a resistivity of about 25 μΩ·cm or less, depending on the thickness 620 of the tungsten-containing layer. At a tungsten-containing layer thickness of about 200 angstroms or greater, the resistivity of tungsten-containing layers 604 and 608 is about 20 μΩ·cm or less. In some embodiments, at a tungsten-containing layer thickness of about 200 angstroms to about 600 angstroms, the resistivity of tungsten-containing layers 604 and 608 is about 17.5 μΩ·cm or less. In some embodiments, at a tungsten-containing layer thickness of about 450 angstroms or greater (e.g., about 450 angstroms to about 600 angstroms), the resistivity of tungsten-containing layers 604 and 608 is about 15 μΩ·cm or less. In some embodiments, the tungsten-containing layer includes a surface roughness of about 3.5 nanometers or less (e.g., about 2 nanometers to about 3 nanometers) calculated by root mean square.

[0086] Unbound by theory, it is believed that the added boron in the nucleation layer enables the growth of bulk tungsten grains in thin film systems (e.g., thicknesses of about 600 angstroms or less, such as about 200 angstroms to about 500 angstroms), reduces electron scattering at tungsten grain boundaries, and provides a reduction in resistivity. During processing operation 506, the delayed growth of bulk tungsten can reduce the size of the contact-filled seams.

[0087] In operation 510, substrate 600 is annealed. Annealing substrate 600 further reduces the resistivity of the substrate. In some embodiments, substrate 600 is annealed for about 1 second to about 10 minutes, such as about 5 seconds to about 120 seconds, such as about 10 seconds to about 100 seconds, such as about 30 seconds to about 60 seconds. In some embodiments, substrate 600 is annealed at a temperature of about 600°C or higher, such as about 700°C to about 1200°C, such as about 800°C to about 1000°C, such as about 850°C to about 950°C, and the chamber pressure is about 30 Torr to about 70 Torr, such as about 50 Torr. In some embodiments, substrate 600 is annealed in the presence of a gas including a nitrogen-containing gas (such as N2 gas), an argon-containing gas (such as Ar gas), a hydrogen-containing gas (such as H2 gas), or combinations thereof. In some embodiments, the gas flows at a volumetric flow rate of about 5 liters per minute, such as 15 liters per minute, such as 10 liters per minute.

[0088] The annealed substrate includes a nucleating layer 604 that has been modified by the annealing process. The atomic ratio of boron to tungsten in the modified nucleating layer is about 1:n, where n is about 4 or less, such as about 1:3 to about 1:1, or about 1:2 to about 1:1. In some embodiments, the modified nucleating layer includes about 10% or more of atomic boron concentration relative to tungsten compared to the unannealed nucleating layer 604, for example, about 2 to 3 times the amount of boron relative to tungsten. For example, in one embodiment, the atomic boron to tungsten ratio of the unannealed nucleating layer is about 1:4 to 1:5, such as about 1:4.5, and after annealing, the boron to tungsten ratio of the modified nucleating layer is about 1:1 to about 1:3, such as about 1:2.

[0089] The annealed substrate includes tungsten-containing layers 604 and 608 that have been modified by annealing. Depending on the thickness 620 of the modified tungsten-containing layer, the resistivity of the modified tungsten-containing layer is about 20 μΩ·cm or less. At a tungsten-containing layer thickness of about 200 angstroms or more, the resistivity of the modified tungsten-containing layer is about 17 μΩ·cm or less. In some embodiments, at a tungsten-containing layer thickness of about 200 angstroms to about 600 angstroms, the resistivity of the modified tungsten-containing layer is about 10 μΩ·cm to 16 μΩ·cm. In some embodiments, at a tungsten-containing layer thickness of about 450 angstroms or more (e.g., about 450 angstroms to about 600 angstroms), the resistivity of the modified tungsten-containing layer is about 10 μΩ·cm to 14 μΩ·cm. In some embodiments, the tungsten-containing layer includes a surface roughness of about 3.5 nanometers or less (e.g., about 2 nanometers to about 3 nanometers) calculated by root mean square. In some embodiments, the resistivity of the modified tungsten-containing layer is reduced by 10% or more, for example, from about 20% to about 40%, compared to the unannealed tungsten-containing layer.

[0090] Unbound by theory, it is believed that annealing the substrate 600 increases the grain size of the tungsten-containing layer structure, contributing to a reduction in resistivity. In some embodiments, measured by X-ray diffraction (XRD) imaging, the grain size of the tungsten-containing layers 604 and 608 increased by about 5% or more after annealing, for example, from about 10% to about 30%, or from about 15% to about 20%. It was further observed that the modified tungsten-containing layer included α-phase tungsten and substantially contained no β-phase tungsten. The α-phase tungsten is stable and has good conductivity. It was also found that the process described herein involves an incubation growth of about 50 Å to about 300 Å, for example, from about 70 Å to about 100 Å, compared to conventional SSW of about 1150 Å to about 1250 Å.

[0091] In a typical semiconductor manufacturing process, after depositing tungsten interstitial filler material 608 into the opening 605, a chemical mechanical polishing (CMP) process can be used to remove the tungsten material capping layer (and the barrier layer disposed thereunder) from the field surface of the substrate. example

[0092] Figure 7 depicts comparison curves illustrating the resistivity of thin film layers formed using the methods and comparison methods described herein, according to some embodiments. Curves 702, 704, 706, and 708 depict the relationship between the film resistivity results and film thickness for each thin film sample. As used herein, the film resistivity was measured using ASTM B193-20 (2020), which uses a KLA Rs-200 resistivity mapping system with a 4-point probe to measure the sheet resistance. The film thickness was measured using a Rigaku MFM65 online XRF wafer inspection system. The film resistivity is obtained by multiplying the sheet resistance by the film thickness.

[0093] Curve 702 corresponds to a thin film formed using a process similar to that described herein before annealing, wherein the boron to tungsten atomic ratio of the nucleation layer is about 1:4.5 or less, for example, about 1:4.6 to about 1:6. The sample thin film of Curve 702 can be formed using operations 502 to 508 of method 500. The sample thin film of Curve 702 is formed by exposing the sample to nitrogen plasma from a remote plasma source, as described in operation 508. Curve 704 corresponds to a thin film deposited using a conventional CVD process. The conventional CVD process shown in Curve 704 provides relatively low resistivity across all thickness ranges; however, the film includes voids and seams within the openings and does not produce good structural properties. The thin film of Curve 702 provides good gap-filling properties that are substantially free of voids and seams; however, at film thicknesses less than 500 angstroms, the resistivity increases to about 20 μΩ·cm and greater. Curve 706 corresponds to films formed using conventional CVD processes, where the boron concentration in the nucleation layer is increased, for example, the boron to tungsten atomic ratio in the nucleation layer is about 1:4 or greater, for example, about 1:3 to about 1:2. It can be seen that increasing the boron concentration in the nucleation layer of films formed using conventional CVD processes provides a reduction in film resistivity. The reduced film resistivity for thicknesses of 200 Å to 600 Å did not achieve a resistivity of about 16 μΩ·cm or lower.

[0094] Curve 708 corresponds to the thin film formed using the pre-annealing processes described herein (operations 502 to 508 of method 500), wherein the boron to tungsten atomic ratio of the nucleation layer is about 1:4 or greater, for example, about 1:3 to about 1:2. The thin film of curve 708 is similar to that of curve 702, but the thin film of curve 708 includes a higher boron concentration in the nucleation layer. The thin film of curve 708 provides good gap-filling properties with no or substantially no voids and seams, and produces low resistivity results in both thicknesses less than 500 angstroms and thicknesses greater than 500 angstroms. Compared to the thin film corresponding to curve 702, the thin film corresponding to curve 708 provides a 10-70% reduction in film resistivity at thicknesses from about 200 angstroms to about 2000 angstroms, while also providing the suppression of gap filling used in post-nucleation layer processing. The reduction in film resistivity is greater in thinner films than in thicker films. Compared to samples formed by conventional CVD processes, samples formed using operations 502 to 508 of method 500 and having a higher boron concentration in the nucleation layer surprisingly provide a reduced resistivity, which is much lower and the roughness is also much lower.

[0095] Figure 8 illustrates the effect of annealing temperature on samples with a tungsten-containing layer approximately 300 angstroms thick. The tungsten-containing layer on each sample was formed using operations 502 to 508 of Method 500 as a control, and the corresponding sample was formed using operations 502 to 510 with annealing. Each pair of data points corresponds to a resistivity measurement at annealing temperatures ranging from 600°C to 850°C, spaced 50°C apart, and is compared with a control sample without annealing. It can be seen that higher annealing temperatures generally correspond to a much larger reduction in resistivity. In addition to the improvement in resistivity, the annealed film also maintains low surface roughness. Unbound by theory, and based on microscopic observations, it is believed that grain growth occurs planarly with a certain increase in film thickness, rather than a rough, vertical growth.

[0096] Figure 9 illustrates the effect of annealing on samples with tungsten-containing layers of varying thicknesses. Curve 902 includes resistivity measurements as a function of film thickness for samples formed using operations 502 to 508 of method 500 as a control, and curve 904 includes resistivity measurements for corresponding samples formed using operations 502 to 510 that have undergone annealing. It can be observed that annealing has a greater effect on thinner films (e.g., less than 300 angstroms).

[0097] Table 1 illustrates the comparison of grain size before and after annealing. The first sample (s1) was formed using operations 502 to 508 of method 500. Before annealing, s1 had a thickness of 227.7 Å and a resistivity of 45.6 μΩ·cm. The measured grain size was 225 Å. The second sample (s2) was formed in the same manner as the first sample (s1) and then annealed at 850 °C for 60 seconds. The film thickness of the sample increased by less than 5%, and the grain size increased to 252 Å. The roughness remained substantially unchanged between the first and second samples. Unbound from theory and as demonstrated by topological imaging, it is believed that grain enlargement occurred in a planar manner, resulting in substantially unchanged roughness and minimized film thickness increase. Due to grain growth, the resistivity of the second sample (s2) decreased relative to the first sample.

[0098] The third sample (s3) was formed using operations 502 to 508 of method 500. Before annealing, s3 had a thickness of 324.4 Å and a resistivity of 16.3 μΩ·cm. The measured grain size was 265 Å. The fourth sample (s4) was formed in the same manner as the third sample (s3) and then annealed at 850 °C for 60 seconds. The film thickness of the sample increased by less than 6%, and the grain size increased to 316 Å. The roughness remained substantially unchanged between the first and second samples. Due to grain growth, the resistivity of the fourth sample (s4) decreased relative to the third sample. As shown with the second sample relative to the first sample, a greater decrease in resistivity was observed in the thinner film. Table 1. Comparison of Grain Sizes s1 s2 s3 s4 Low R SSW Low R SSW w / RTP Low R SSW Low R SSW w / RTP Grain size (angstroms) 225 252 265 316 Thickness (angstroms) 227.7 237.9 324.4 342.9 Resistivity (μΩ·cm) 45.6 15.1 16.3 12.6 Other forms

[0099] This disclosure may include the following non-limiting forms and / or embodiments:

[0100] Clause 1. A structure on a substrate, the structure comprising: an opening within the substrate; and a tungsten-containing layer comprising: a nucleation layer disposed along a sidewall of the opening, wherein the nucleation layer comprises boron and tungsten; and a filling layer disposed above the nucleation layer within the opening, wherein the resistivity of the tungsten-containing layer is about 16 μΩ·cm or less, wherein the thickness of the tungsten-containing layer is about 200 angstroms to about 600 angstroms, wherein the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between opposite sidewall portions of the opening.

[0101] Clause 2. The structure as described in Clause 1, wherein the ratio of boron to tungsten in the nucleating layer is about 1:4 to about 1:1.

[0102] Clause 3. The structure as described in Clause 1 or Clause 2, wherein the ratio of boron to tungsten is about 1:3 to 1:2.

[0103] Clause 4. The structure as described in any of Clauses 1 to 3 further includes: an adhesive layer disposed between the substrate and the nucleation layer.

[0104] Clause 5. The structure as described in any of Clauses 1 to 4, wherein the tungsten-containing layer further comprises: nitrogen, oxygen, fluorine, or a combination thereof.

[0105] Clause 6. A structure on a substrate, the structure comprising: an opening within the substrate; an adhesive layer disposed on a sidewall of the opening; and a tungsten-containing layer disposed above the adhesive layer within the sidewall, the resistivity of the tungsten-containing layer being about 16 μΩ·cm or less, and the thickness of the tungsten-containing layer being about 200 angstroms to about 600 angstroms, wherein the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between opposite sidewall portions of the opening.

[0106] Clause 7. The structure as described in Clause 6, wherein the thickness of the tungsten-containing layer is from about 300 angstroms to about 600 angstroms, and wherein the resistivity of the tungsten-containing layer is about 14 μΩ·cm or less.

[0107] Clause 8. The structure as described in Clause 6 or Clause 7, wherein the tungsten-containing layer includes a nucleation layer comprising boron.

[0108] Clause 9. The structure as described in any of Clauses 6 to 8, wherein the ratio of boron to tungsten is about 1:3 to 1:1.

[0109] Clause 10. The structure as described in any of Clauses 6 to 9, wherein the tungsten-containing layer comprises a surface roughness of about 3.5 nanometers or less, calculated by root mean square.

[0110] Clause 11. The structure as described in any of Clauses 6 to 10, wherein the tungsten-containing layer comprises a surface roughness of about 2 nanometers to about 3 nanometers calculated by root mean square.

[0111] Clause 12. A method of forming a structure on a substrate, the method comprising the steps of: exposing the substrate to a tungsten-containing precursor gas at a precursor gas flow rate; exposing the substrate to a reducing agent comprising boron at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are used alternately in a cycle to form a nucleation layer over the substrate within at least one opening in the substrate; depositing a fill layer over the nucleation layer within the at least one opening; and annealing the substrate at about 600°C to about 1000°C.

[0112] Clause 13. The method of Clause 12 further includes the step of: transferring the substrate to a rapid heat treatment chamber prior to annealing the substrate.

[0113] Clause 14. The method as described in Clause 12 or Clause 13, wherein annealing the substrate includes the step of exposing the substrate to hydrogen gas.

[0114] Clause 15. The method as described in any of Clauses 12 to 14, wherein the reducing agent flow rate is about 300 sccm or greater.

[0115] Clause 16. The method as described in any of Clauses 12 to 15, wherein the precursor gas flow rate is about 60 sccm or less.

[0116] Clause 17. The method of any of Clauses 12 to 16 further comprises the steps of: filling the reservoir with the reducing agent using a reservoir valve disposed upstream of the reservoir, and allowing the reducing agent to flow from the reservoir to the process volume by opening a mass flow control valve disposed between the process volume including the substrate and the reservoir.

[0117] Clause 18. The method of any of Clauses 12 to 17, wherein filling the reservoir further comprises the step of: opening the reservoir valve when the pressure in the reservoir is below a predetermined pressure.

[0118] Clause 19. The method as described in any of Clauses 12 to 18, wherein the substrate is annealed for about 1 second to about 10 minutes.

[0119] Clause 20. The method as described in Clause 19, wherein the substrate is annealed for about 10 seconds to about 60 seconds.

[0120] Clause 21. The method of any of Clauses 12 to 20, wherein annealing the substrate comprises the step of: passing a gas through the substrate, the gas being selected from the group consisting of nitrogen-containing gases, argon-containing gases, hydrogen-containing gases, or combinations thereof.

[0121] Clause 22. The method as described in any of Clauses 12 to 21, wherein the substrate is annealed from a plurality of heating lamps disposed above the substrate.

[0122] Clause 23. The method as described in any of Clauses 12 to 22, wherein the substrate is annealed at about 700°C to about 900°C.

[0123] Clause 24. The method as described in any of Clauses 12 to 23, wherein the ratio of the reducing agent gas flow rate to the precursor agent flow rate, by volume, is m:1, where m is about 5 or greater.

[0124] Clause 25. A method of forming a structure on a substrate, the method comprising the steps of: exposing the substrate to a tungsten-containing precursor gas at a precursor gas flow rate; exposing the substrate to a reducing agent comprising boron at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are cyclically used alternately to form a nucleation layer over the substrate within at least one opening in the substrate; depositing a filler layer over the nucleation layer within the at least one opening, wherein the filler layer and the nucleation layer together form a tungsten-containing layer having a first resistivity; and annealing the tungsten-containing layer at about 600°C to about 1000°C to form a modified tungsten-containing layer having a second resistivity lower than the first resistivity.

[0125] Clause 26. The method as described in Clause 25, wherein the second resistivity is about 10% to 50% lower than the first resistivity.

[0126] While the foregoing description is an embodiment of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from its essential scope, and the scope thereof is determined by the following claims.

[0127] 11: Patterned Surface 12: Dielectric layer 14: Barrier material layer 15: Tungsten layer 20: Gap 24: Seam 200: Processing System 202: Processing Chamber 204: Gas delivery system 208: System Controller 210: Chamber cover assembly 212: Sidewall 214: Base of the chamber 215: Processing volume 216: Cover plate 217: Exhaust system 218: Showerhead 219: Gas distribution volume 220: Substrate support assembly 221: Processing Area 222: Substrate support 223: Gas Inlet 225: Barrier Plate 226: Circular Channel 227: First annular gasket 228: Second Pad 229: Heater 230:Substrate 231: First power supply 232: Opening 235: Shielding ring 236: Purification Ring 237: Purified Gas Source 238: Bypass gas source 240: Deposition gas source 262: Support shaft 263: First heater 264: Second heater 265: Corrugated pipe 266: Lifting Pin Assembly 267: Lifting pin 268: Lifting Pin Hoop 271: Door 272: Vacuum Source 280: Main body of the chamber 291: Flow divider valve 294: Catheter System 295: CPU 296: Memory 297: Support Circuit 302: First Gas Source 304: Refill valve 306: Storage 308: Pressure gauge 310: Valves 312: Valves 314: Second gas source 400: Substrate Processing System 402: Heat treatment chamber 404: Process gas source 406: Processing Area 408: Sidewall 410: Base 412: Window Components 414: Radiant Energy Component 416: Lamp 418: Socket 420: Optical tube 422:Outer wall 424: First Window 426: Second Window 428: Catheter 430: Support ring 432: Rotatable cylinder 434: Reflecting surface 436: Temperature probe 438: Magnetic Rotor 440: Protruding ears 442: Magnet Region 444: Circular Well 446: Lid 448: Magnetic stator 450: Electromagnet 452: Linear Actuator 454: Support component 456: Axis 458: Chamber entrance 460: Inbound / Outbound Ports 500: Methods 502: Operation 504: Operation 506: Operation 508: Operation 510: Operation 600:Substrate 601: Patterned Surface 602: Dielectric material layer 603: Adhesive layer 604: Nucleation layer 605: Opening 606: Treatment of free radicals 608: Tungsten interstitial filling material 620: Thickness 702: Curve 704: Curve 706: Curve 708: Curve 902: Curve 904: Curve 10A:Substrate 15A: Tungsten Characteristics 15B: Tungsten capping layer 206A: First Free Radical Generator 206B: Second free radical generator 281A: Volume of the first plasma chamber 281B: Volume of the second plasma chamber 282A: Plasma Processing 282B: Cleaning Plasma 287A: First Gas Source 287B: Second Gas Source 290A: First valve 290B: Second valve 293A: Power Supply 293B: Power Supply 294B: Second catheter 294D: Fourth catheter 294E: Fifth catheter 294F: Sixth catheter W: substrate

[0128] Domestic storage information (please note in order of storage institution, date, and number) none

[0129] Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A structure on a substrate, the structure comprising: An opening within the substrate; And a tungsten-containing layer, comprising: a nucleation layer disposed along the sidewall of the opening, wherein the nucleation layer comprises boron and tungsten, wherein the ratio of boron to tungsten in the nucleation layer is from about 1:4 to about 1:1; and a filling layer disposed above the nucleation layer within the opening, wherein the resistivity of the tungsten-containing layer is about 16 μΩ·cm or less, wherein the thickness of the tungsten-containing layer is from about 200 angstroms to about 600 angstroms, wherein the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between opposite sidewall portions of the opening.

2. The structure as described in claim 1, wherein the ratio of boron to tungsten is about 1:3 to 1:

2.

3. The structure as described in claim 1, further comprising: An adhesive layer is disposed between the substrate and the nucleation layer.

4. The structure as described in claim 1, wherein the tungsten-containing layer further comprises: Nitrogen, oxygen, fluorine, or combinations thereof.

5. A structure on a substrate, the structure comprising: An opening within the substrate; An adhesive layer is provided on one side wall of the opening; And a tungsten-containing layer disposed above the adhesive layer within the sidewall, the resistivity of the tungsten-containing layer being about 16 μΩ·cm or less, the thickness of the tungsten-containing layer being about 200 angstroms to about 600 angstroms, wherein the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between the opposite sidewall portions of the opening, and wherein the ratio of boron to tungsten is about 1:3 to 1:

1.

6. The structure as claimed in claim 5, wherein the thickness of the tungsten-containing layer is from about 300 angstroms to about 600 angstroms, and wherein the resistivity of the tungsten-containing layer is about 14 μΩ·cm or less.

7. The structure as claimed in claim 5, wherein the tungsten-containing layer includes a nucleation layer comprising boron.

8. The structure as claimed in claim 5, wherein the tungsten-containing layer includes a surface roughness of about 3.5 nanometers or less, calculated by root mean square.

9. The structure as claimed in claim 5, wherein the tungsten-containing layer includes a surface roughness of about 2 nanometers to about 3 nanometers calculated by root mean square.

10. A method of forming a structure on a substrate, the method comprising the steps of: exposing the substrate to a tungsten-containing precursor gas at a precursor gas flow rate; filling a reservoir with the reducing agent using a reservoir valve disposed upstream of a reservoir; allowing the reducing agent to flow from the reservoir to the process volume by opening a mass flow control valve disposed between a process volume including the substrate and the reservoir; exposing the substrate to the reducing agent including boron at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are cyclically used alternately to form a nucleation layer over the substrate within at least one opening; depositing a filler layer over the nucleation layer within the at least one opening; and annealing the substrate at about 600°C to about 1000°C.

11. The method of claim 10 further includes the step of: transferring the substrate to a rapid heat treatment chamber before annealing the substrate.

12. The method of claim 10, wherein annealing the substrate includes the step of exposing the substrate to a hydrogen gas.

13. The method of claim 10, wherein the reducing agent flow rate is about 300 sccm or greater.

14. The method of claim 12, wherein the precursor gas flow rate is about 60 sccm or less.

15. The method of claim 10, wherein filling the reservoir further comprises the step of: opening the reservoir valve when a pressure in the reservoir is lower than a predetermined pressure.

16. The method of claim 10, wherein the substrate is annealed for about 1 second to about 10 minutes.

17. The method of claim 16, wherein the substrate is annealed for about 10 seconds to about 60 seconds.

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