Method for forming low-resistivity tungsten features

Abstract

A substrate structure is provided that includes a tungsten-containing layer including a nucleation layer and a fill layer. The nucleation layer is disposed along a sidewall of an opening. The nucleation layer includes boron and tungsten. The fill layer is disposed over the nucleation layer within the opening. The tungsten-containing layer includes a resistivity of about 16 μΩ·cm or less. The tungsten-containing layer has a thickness of about 200 Å to about 600 Å. The thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between opposing sidewall portions of the opening.

Description

Technical Field

[0001] Embodiments of this specification relate to methods used in the manufacture of electronic devices, and more particularly, to methods used to form tungsten features within semiconductor devices.

Background Art

[0002] Tungsten (W) is widely used in the manufacture of integrated circuit (IC) devices to form conductive features where relatively low electrical resistance and relatively high resistance to electromigration are desired. For example, tungsten may be used as a metal fill material to form source contacts, drain contacts, metal gate fills, gate contacts, interconnects (e.g., horizontal features formed on 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 above and below the dielectric material layer). Tungsten is also commonly used to form bit lines and word lines used to address individual memory cells within a memory cell array of a dynamic random access memory (DRAM) device due to its relatively low resistivity.

[0003] As circuit density increases and device features continue to shrink to meet the requirements of next-generation semiconductor devices, it is becoming increasingly difficult to reliably manufacture tungsten features. Problems such as voids and seams formed during conventional tungsten deposition processes are amplified as feature sizes decrease, which can negatively impact device performance and reliability or even render the device inoperable.

[0004] Therefore, there is a need for a process for filling contact features that are void- and seam-free or substantially so and have a low resistivity for various film thicknesses.

Summary of the Invention

[0005] A structure is provided that includes a tungsten-containing layer comprising a nucleation layer and a packed layer. The nucleation layer is positioned along the sidewall of the opening. The nucleation layer contains boron and tungsten. The packed layer is positioned on top of the nucleation layer within the opening. The tungsten-containing layer has a resistivity of about 16 μΩ·cm or less. The tungsten-containing layer has a thickness of about 200 Å to about 600 Å. The thickness of the tungsten-containing layer is half the width of the tungsten-containing layer positioned within the opening between the opposing sidewall portions of the opening.

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

[0007] A method for forming a structure is provided. The method includes exposing a substrate to a tungsten-containing precursor gas at a precursor gas flow rate. The substrate is then exposed to a boron-containing reducing agent at a reducing agent flow rate. The tungsten-containing precursor gas and the reducing agent are applied alternately and periodically to form a nucleation layer on the substrate within at least one opening in the substrate. The method includes depositing a packed layer on the nucleation layer within at least one opening. The substrate is then annealed at approximately 600°C to approximately 1000°C.

[0008] To allow for a more detailed understanding of the above-mentioned features of this disclosure, a more specific description of this disclosure, as summarized above, can be given by referring in part to embodiments shown in the accompanying drawings. However, it should be noted that the accompanying drawings show only exemplary embodiments and should not be considered limiting in scope, as other equally valid embodiments may be recognized. [Brief explanation of the drawing]

[0009] [Figure 1A]This is a schematic cross-sectional view of a portion of a substrate showing undesirable void or seam formation in tungsten features formed by conventional methods. [Figure 1B] This is a schematic cross-sectional view of a portion of a substrate showing undesirable void or seam formation in tungsten features formed by conventional methods. [Figure 2A] This is a schematic side view of a processing system that can be used to carry out the method described herein according to one embodiment. [Figure 2B] This is an enlarged cross-sectional view of a part of the processing system shown in Figure 2A, according to one embodiment. [Figure 3] This is an enlarged cross-sectional view of a part of the processing system shown in Figure 2A, according to one embodiment. [Figure 4] This is a schematic side view of a rapid heat treatment system that can be used to carry out the method described herein, according to one embodiment. [Figure 5] This figure shows a method for processing a substrate according to one embodiment. [Figure 6A] This is a schematic cross-sectional side view of a substrate before processing according to one embodiment. [Figure 6B] This is a schematic cross-sectional side view of a substrate in one step of processing according to one embodiment. [Figure 6C] This is a schematic cross-sectional side view of a substrate in one step of processing according to one embodiment. [Figure 7] This is a comparison curve showing the resistivity of film layers formed using the methods and comparison methods described herein at various film thicknesses according to some embodiments. [Figure 8] This is a comparison curve showing the resistivity of film layers formed using the method herein, before and after annealing at various temperatures, according to some embodiments. [Figure 9] This is a comparison curve showing the resistivity of film layers formed using the method herein, before and after annealing at various film thicknesses, according to some embodiments. [Modes for carrying out the invention]

[0010] For ease of understanding, the same reference numerals are used to indicate identical elements common to the drawings, where possible. Elements and features of one embodiment are intended to be usefully incorporated into other embodiments without further explanation.

[0011] The embodiments described herein generally pertain to the manufacture of electronic devices, and more specifically to systems and methods for forming low-resistivity tungsten features in semiconductor device manufacturing schemes.

[0012] Figure 1A is a schematic cross-sectional view of a substrate 10A showing an undesirable void 20 formed during a conventional tungsten deposition process. Here, the substrate 10A includes a patterned surface 11 which comprises a dielectric layer 12 having a high aspect ratio opening formed inside (shown as being filled with a portion of the tungsten layer 15), a barrier material layer 14 deposited on the dielectric layer 12 to back the opening, and a tungsten layer 15 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) process, conformally depositing (growing) tungsten on the patterned surface 11 to fill the opening. The tungsten layer 15 forms tungsten features 15A in the opening and forms an overburden of material (tungsten overburden layer 15B) on the field of the patterned surface 11.

[0013] In Figure 1A, the opening has a non-uniform profile, being narrower at the surface of the substrate 10A and widening (becoming outwardly arc-shaped) as the opening extends inward from the surface into the dielectric layer 12. As shown, the overhang portions of the conformal tungsten layer 15 grow together to block or "pinch off" the opening entrance before the opening is fully filled, causing undesirable voids 20, i.e., defects in tungsten material, in the tungsten feature 15A. If the voids 20 open (become exposed) during the subsequent CMP process, the polishing fluid may penetrate the tungsten feature 15A, and the chemically active components of the polishing fluid may cause further loss of tungsten material, e.g., coring (keyholeing) of the undesirable feature by corrosion and / or static etching of the tungsten material. This undesirable loss of tungsten can lead to device performance and reliability issues, or ultimately to complete device failure. Even without void formation, using conventional tungsten deposition processes such as those shown in Figure 1B, undesirable seam formation in tungsten features is almost unavoidable.

[0014] Figure 1B is a schematic cross-sectional view of substrate 10B showing 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) having a substantially uniform profile as the opening extends from the surface of substrate 10B into the dielectric layer 12. The opening is filled with tungsten and no voids are formed. Nevertheless, as the tungsten layer 15 grows conformally outward from the walls of the opening, an undesirable seam 24 is formed in the opening, extending through the center of the tungsten feature 15A. Similar to the void 20 shown in Figure 1A, the seam 24 is vulnerable to corrosion by the chemically active components of the tungsten polishing solution, and if the seam 24 is exposed during the CMP process, it can lead to an undesirable loss of tungsten material from feature 15A.

[0015] Accordingly, embodiments of this specification provide a processing system configured to perform combinations of the individual embodiments of the method without transferring the substrate between processing chambers, thereby improving the overall substrate processing throughput and capacity of the tungsten gap-filling processing scheme described herein.

[0016] Generally, gap-filling treatment schemes include forming differential tungsten deposition inhibition profiles in characteristic openings formed on the substrate surface, filling the openings with tungsten material according to the inhibition profiles, and depositing tungsten overburden on the field surface of the substrate. Forming tungsten deposition inhibition profiles typically involves forming a tungsten nucleation layer and treating the tungsten nucleation layer with an active nitrogen nuclide, such as a treatment radical. The nitrogen treatment radical is incorporated into a portion of the nucleation layer, for example, by adsorption of the nitrogen nuclide and / or by reaction with metallic tungsten in the nucleation layer to form tungsten nitride (WN). The adsorbed nitrogen and / or nitrided surface of the tungsten nucleation layer preferably delay (inhibit) tungsten nucleation and, therefore, delay (inhibit) subsequent tungsten deposition.

[0017] In some embodiments, the treatment radicals are formed remotely from the substrate treatment chamber by using a remote plasma source fluid-coupled to the substrate treatment chamber. The desired inhibitory effect on the field of the patterned surface, and the desired inhibitory profile at the openings formed on the patterned surface, are achieved by controlling the treatment conditions within the treatment chamber, such as temperature and pressure, and by controlling the concentration, flux, and energy of the treatment radicals on the substrate surface. Typically, the treatment radicals are formed from non-halogen nitrogen-containing gases such as N2, NH3, NH4, or combinations thereof.

[0018] The tungsten nucleation and deposition process of the gap filling process generally includes flowing a tungsten-containing precursor and a reducing agent into a processing chamber and exposing the substrate surface to them. The tungsten-containing precursor and the reducing agent react on the surface of the substrate in one of a chemical vapor deposition (CVD) process, a pulsed CVD process, an atomic layer deposition (ALD) process, or a combination thereof to deposit a tungsten material on the surface of the substrate.

[0019] The processing system described herein is configured to periodically perform a chamber cleaning operation, and undesirable tungsten residues are removed from the inner surface of the processing chamber using a cleaning chemical such as an activated halogen nuclide formed remotely from the processing chamber, for example, a cleaning chemical containing fluorine or chlorine (cleaning) radicals.

[0020] The chamber cleaning operation generally includes flowing halogen cleaning radicals into the processing chamber, reacting the cleaning radicals with tungsten residues to form volatile tungsten nuclides, and discharging the volatile tungsten nuclides from the processing chamber through an exhaust section. The chamber cleaning operation is typically performed between substrate processes, that is, after the processed substrate is removed from the processing chamber and before the next processed substrate to be processed is received into the processing chamber.

[0021] Figures 2A - 2B schematically show a processing system 200 that can be used to perform the bottom-up tungsten gap filling substrate processing method described herein. Here, the processing system is configured to provide different processing conditions desirable for each of the nucleation process, the inhibition process, the selective gap filling process, and the overburden deposition process within a single processing chamber 202, that is, without transferring the substrate between multiple processing chambers.

[0022] As shown in Figure 2A, the processing system 200 includes a processing chamber 202, a gas supply 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 lid assembly 210, one or more side walls 212, and a chamber base 214, which together define a processing volume 215. The processing volume 215 is fluidly coupled to an exhaust unit 217, such as one or more vacuum pumps, used to maintain the processing volume 215 at or below atmospheric pressure and to discharge the processing gas and processing by-products from there.

[0023] The chamber lid assembly 210 includes a lid plate 216 and a shower head 218 coupled to the lid plate 216, which together define a gas distribution volume 219. Here, the lid plate 216 is maintained at a desired temperature using one or more heaters 229 thermally coupled thereto. The shower head 218 faces a substrate support assembly 220 located within the processing volume 215. As described below, the substrate support assembly 220 is configured to move a substrate support 222, and therefore a substrate 230 placed on the substrate support 222, between a raised substrate processing position (illustrated) and a lowered substrate transfer position (not shown). When the substrate support assembly 220 is in the raised substrate processing position, the shower head 218 and the substrate support 222 define a processing area 221.

[0024] The gas supply system 204 is fluidly coupled to the processing chamber 202 via a gas inlet 223 (Figure 2B) positioned through the lid plate 216. The processing gas or cleaning gas supplied by the use of the gas supply system 204 flows through the gas inlet 223 into the gas distribution volume 219 and is distributed to the processing area 221 through multiple openings 232 (Figure 2B) in the shower head 218. In some embodiments, the chamber lid assembly 210 further includes a perforated shielding plate 225 positioned between the gas inlet 223 and the shower head 218. In these embodiments, the gas flowing into the gas distribution volume 219 is first diffused by the shielding plate 225, together with the shower head 218, to provide a more uniform or desired distribution of the gas flow to the processing area 221.

[0025] The processing gas and processing by-products are discharged radially outward from the processing region 221 through an annular channel 226 surrounding the processing region 221. The annular channel 226 may be formed in a first annular liner 227 located radially inward of one or more sidewalls 212 (as shown in the figure), or it may be formed in one or more sidewalls 212. In some embodiments, the processing chamber 202 includes one or more second liners 228 used to protect the inner surface of one or more sidewalls 212 or the chamber base 214 from corrosive gases and / or undesirable material deposits.

[0026] In some embodiments, a purge gas source 237, fluidly connected to the processing volume 215, is used to introduce a chemically inert purge gas, such as argon (Ar), into a region located beneath the substrate support 222, for example, through an opening in the chamber base 214 surrounding the support shaft 262. 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) during substrate processing. Typically, the purge gas introduced through the chamber base 214 flows upward from there, around the edges of the substrate support 222, and is discharged from the processing volume 215 through an annular channel 226. The purge gas reduces unwanted material deposition on the surface beneath the substrate support 222 by reducing and / or preventing the flow of material precursor gases into the substrate support 222.

[0027] The substrate support assembly 220 includes a movable support shaft 262 that is sealed and extends through the chamber base 214, such as being surrounded by a bellows 265 in the region below the chamber base 214, and a substrate support 222 positioned on the movable support shaft 262. To facilitate the transfer of the substrate to and from the substrate support 222, the substrate support assembly 220 includes a lift pin assembly 266 comprising a plurality of lift pins 267 coupled to or engaged with a lift pin hoop 268. The plurality of lift pins 267 are movably positioned at 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 lift pins 267 extend above the substrate receiving surface of the substrate support 222 to lift the substrate 230 from the substrate receiving surface, providing access to the back (inactive) surface of the substrate 230 by a substrate handler (not shown). When the substrate support 222 is in the raised or processing position (as shown in the figure), the multiple lift pins 267 retract below the substrate receiving surface of the substrate support 222, allowing the substrate 230 to rest on the substrate receiving surface.

[0028] The substrate 230 is transferred to and from the substrate support 222 through a slit valve located in one of the door 271, for example, one or more side walls 212. Here, one or more openings in the area surrounding the door 271, for example, an opening in the door housing, are fluidly coupled to a purge gas source 237, for example, an Ar gas source. The purge gas is used to prevent the processing gas and cleaning gas from coming into contact with the seal surrounding the door and / or degrading the seal, and thus to extend its effective life.

[0029] The substrate support 222 is configured for use as a vacuum chuck, in which the substrate 230 is fixed 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, for example, if the processing chamber 202 is configured for direct plasma processing, the substrate support 222 may be configured for use as an electrostatic chuck. 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.

[0030] As shown in the figure, the substrate support assembly 220 features a dual-zone temperature control system for providing independent temperature control in different regions of the substrate support 222. The different temperature control regions of the substrate support 222 correspond to different regions of the substrate 230 placed on the substrate support 222. Here, the temperature control system includes a first heater 263 and a second heater 264. The first heater 263 is located in the central region of the substrate support 222, and the second heater 264 is located radially outward from the central region so as to surround the first heater. In other embodiments, the substrate support 222 may have a single heater or three or more heaters.

[0031] In some embodiments, the substrate support assembly 220 further includes an annular shadow ring 235 used to prevent undesirable material deposition on the circumferential beveled edges of the substrate 230. During substrate transfer to and from the substrate support 222, i.e., when the substrate support assembly 220 is in a lowered position (not shown), the shadow ring 235 rests on an annular ledge in 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 shadow ring 235 such that the shadow ring 235 is tangent to the substrate 230 placed on the substrate support 222. Here, the shadow ring 235 is molded such that when the substrate support assembly 220 is in an elevated substrate processing position, the radially inward portion of the shadow ring 235 is positioned above the beveled edges of the substrate 230.

[0032] In some embodiments, the substrate support assembly 220 further includes an annular purge ring 236 positioned on the substrate support 222 so as to be circumstantial to the substrate 230. In these embodiments, a shadow ring 235 may be positioned on the purge ring 236 when the substrate support assembly 220 is in a raised substrate processing position. Typically, the purge ring 236 features a plurality of radially inward openings that fluidly connect to a purge gas source 237. During substrate processing, the purge gas flows into an annular region defined by the shadow ring 235, the purge ring 236, the substrate support 222, and the beveled edge of the substrate 230, preventing the processing gas from entering the annular region and causing undesirable material deposition on the beveled edge of the substrate 230.

[0033] In some embodiments, the processing chamber 202 is configured for direct plasma processing. In these embodiments, the showerhead 218 may be electrically coupled to a first power supply 231, such as an RF power supply, which supplies power to ignite and maintain the plasma of the processing gas flowing into the processing area 221 via capacitive coupling. In some embodiments, the processing chamber 202 includes an inductive plasma generator (not shown), the plasma being formed by inductively coupling RF power to the processing gas.

[0034] The processing system 200 is advantageously configured to perform each of the tungsten nucleation, inhibition, and bulk tungsten deposition processes of a void-free, seam-free tungsten gap-filling process scheme without removing the substrate 230 from the processing chamber 202. The gas used to perform each of the individual processes of the gap-filling process scheme and to clean residues from the inner surface of the processing chamber is supplied to the processing chamber 202 using a gas supply system 204 that is fluidly coupled to the processing chamber 202.

[0035] Generally, the gas supply system 204 includes one or more remote plasma sources, here first and second radical generators 206A-206B, a deposition gas source 240, and a conduit system 294 (e.g., multiple conduits 294A-294F) that fluidly couples the radical generators 206A-206B and the deposition gas source 240 to the lid assembly 210. The gas supply system 204 further includes a plurality of separation valves, here first and second valves 290A-290B, respectively, positioned between the radical generators 206A-206B and the lid plate 216, which can be used to fluidly separate each of the radical generators 206A-206B from the processing chamber 202 and from each other.

[0036] Each of the radical generators 206A to 206B features a chamber body 280 defining the respective first and second plasma chamber volumes 281A to 281B (Figure 2B). Each of the radical generators 206A to 206B is coupled to the respective power supplies 293A to 293B. The power supplies 293A to 293B are used to ignite and maintain the plasmas 282A to 282B of the gas supplied to the plasma chamber volumes 281A to 281B from the corresponding first or second gas sources 287A to 287B, which are fluid-coupled to the plasma chamber volumes 281A to 281B. In some embodiments, the first radical generator 206A generates radicals used in differential inhibition processes. For example, the first radical generator 206A may be used to ignite and maintain the processed plasma 282A from a halogen-free mixed gas supplied to the first plasma chamber volume 281A from the first gas source 287A. A second radical generator 206B may be used to generate cleaning radicals used in the chamber cleaning process by igniting and maintaining a cleaning plasma 282B from a halogen-containing mixed gas supplied from a second gas source 287B to a second plasma chamber volume 281B.

[0037] Typically, nitrogen-treated radicals have a relatively short lifetime (compared to halogen-washed radicals) and may be relatively susceptible to recombination due to collisions with other nuclides in the surface and / or treatment plasma ejecta within the gas supply system 204. Therefore, in embodiments herein, the first radical generator 206A is typically positioned closer to the gas inlet 223 than the second radical generator 206B, for example, so that the travel distance from the first plasma chamber volume 281A to the treatment area 221 is relatively short.

[0038] In some embodiments, the first radical generator 206A is also fluid-coupled to a second gas source 287B, which supplies a halogen-containing conditioning gas used in the plasma source conditioning process to the first plasma chamber volume 281A. In these embodiments, the gas supply system 204 may further include a plurality of flow-distributing valves 291 that can be operated to guide the halogen-containing mixed gas from the second gas source 287B to the first plasma chamber volume 281A.

[0039] Suitable remote plasma sources that can be used with one or both of the radical generators 206A-206B include radio frequency (RF) or very high frequency (VHRF) capacitively coupled plasma (CCP) sources, inductively coupled plasma (ICP) sources, microwave-inductive (MW) plasma sources, electron cyclotron resonance (ECR) chambers, or high-density plasma (HDP) chambers.

[0040] As shown in the figure, the first radical generator 206A is fluid-coupled to the processing chamber 202 by using first and second conduits 294A-294B that extend upward from the gas inlet 223 and connect to the outlet of the first plasma chamber volume 281A. A first valve 290A, positioned between the first conduit 294A and the second conduit 294B, is used to selectively fluidize the first radical generator 206A from the processing chamber 202 and the rest of the gas supply system 204. Typically, the first valve 290A is closed during the chamber cleaning process to prevent activated cleaning gases, such as halogen radicals, from flowing into the first plasma chamber volume 281A and damaging its surface.

[0041] The second radical generator 206B is fluidly coupled to the second conduit 294B and therefore to the processing chamber 202 by using the third and fourth conduits 294C-294D. The second radical generator 206B is selectively isolated from the processing chamber 202 and the rest of the gas supply system 204 by using a second valve 290B located between the third conduit 294C and the fourth conduit 294D.

[0042] The deposition gas, for example, a tungsten-containing precursor and a reducing agent, is supplied from the deposition gas source 240 to the processing chamber 202 using a fifth conduit 294E. As shown in the figure, the fifth conduit 294E is coupled to the second conduit 294B at a position close to the gas inlet 223 so that the first and second radical generators 206A and 206B can be separated from the deposition gas introduced into the processing chamber 202 using the first and second valves 290A and 290B, respectively. In some embodiments, the gas supply system 204 further includes a sixth conduit 294F coupled to the fourth conduit 294D at a position close to the second valve 290B. The sixth conduit 294F is fluidly coupled to a bypass gas source 238, for example, an argon (Ar) gas source, which can be used to periodically purge undesirable residual cleaning gases, residual inhibiting gases, and / or residual sediment gases from a portion of the gas supply system 204.

[0043] The operation of the processing system 200 is facilitated by the system controller 208. The system controller 208 includes a programmable central processing unit, here a CPU 295, which can operate together 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 used in industrial environments, such as a programmable logic control unit (PLC), for controlling various chamber components and subprocessors. Memory 296 coupled to the CPU 295 facilitates the operation of the processing chamber. The support circuitry 297 conventionally includes caches, clock circuits, input / output subsystems, power supplies, etc., and combinations thereof, coupled to the CPU 295 and various components of the processing system 200, thereby facilitating the control of board processing operations.

[0044] The instructions in instruction memory 296 are in the form of a program product, such as a program that implements the method of the present disclosure. In one example, the present 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 the embodiments (including the method of the present specification). Thus, a computer-readable storage medium is an embodiment of the present disclosure if it carries computer-readable instructions that direct the functionality of the method of the present specification.

[0045] The processing system 200 described above can be used to perform nucleation, inhibition, and gap-filling deposition, and thus provides a single-chamber, seam-free tungsten gap-filling solution.

[0046] Figure 3 is an enlarged cross-sectional view of a 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, such as a reducing agent gas source, and a second gas source 314, such as a tungsten-containing precursor. The reducing agent gas source 302 is fluidly connected to a reservoir 306. The reservoir 306 is continuously filled with the reducing gas source 302 or replenished using a replenishment valve 304. The pressure in the reservoir 306 is monitored using a pressure gauge 308. It has been found that the use of the reservoir 306 makes it possible to rapidly release a large amount of gas into the processing chamber 202. The large amount of gas is released at a large gas flow rate (e.g., about 200 sccm or more, such as about 300 sccm or more) of reducing gas flowing into the processing chamber 202 during operations such as pulsing. The reducing gas is released from the reservoir 306 into the chamber 202 via a valve 310 located along the conduit 294E. A second gas source 314 is fluidly connected to the chamber 202 via a conduit 294E. The second gas source 314 delivers a tungsten-containing precursor to the chamber 202 via a valve 312. One or more of the valves 304, 310, and 312 are controlled using a controller such as a system controller 208. In some embodiments, one or more of the valves are switched between an open state and a closed state at predetermined intervals for predetermined times, depending on operating parameters.

[0047] After processing the substrate in the processing chamber 202, the substrate is transferred to a second processing system for annealing the substrate, such as the substrate processing system 400 shown in Figure 4. The substrate processing system 400 may be a rapid heat treatment (RTP) apparatus. The 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 the processing area 406 of the heat treatment chamber 402. The processing area 406 is enclosed by one or more side walls 408 (e.g., four side walls or a single side wall for a circular processing area 406) and a base 410. The tops of the side walls 408 may be sealed to a window assembly 412 (e.g., using "O" rings). A radiant energy assembly 414 is located on top of the window assembly 412 and coupled to it. The radiant energy assembly 414 has a plurality of lamps 416, which may be tungsten halogen lamps, each lamp mounted on a receptacle 418 and positioned to emit electromagnetic radiation into the processing area 406. The window assembly 412 in Figure 4 has a plurality of optical pipes 420, but the window assembly 412 may simply have a flat, solid window without optical pipes. The window assembly 412 has an outer wall 422 (e.g., a cylindrical outer wall) that forms a rim surrounding the window assembly 412 on its outer circumference. The window assembly 412 also has a first window 424 covering the first ends of the plurality of optical pipes 420, and a second window 426 covering the second ends of the plurality of optical pipes 420 on the opposite side of the first ends. The first window 424 and the second window 426 extend to and engage with the outer wall 422 of the window assembly 412, enclosing and sealing the interior of the window assembly 412 containing the plurality of optical pipes 420. When optical pipes are used in this manner, a vacuum can be created within the multiple optical pipes 420 by applying a vacuum to one of the multiple optical pipes 420 through a conduit 428 that penetrates the outer wall 422, and this optical pipe 420 is fluidly connected to the remaining optical pipes.

[0048] The substrate W is supported within the heat treatment chamber 402 by a support ring 430 in a 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 rotate 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 substrate W during processing. Alternatively, a separate reflector (not shown) can be placed 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 positioned through the base 410 of the heat treatment chamber 402 to detect the temperature of the substrate W. If a separate reflector is used as described above, the temperature probes 436 are also positioned through the separate reflector to optically access the electromagnetic radiation coming from the substrate W.

[0049] The rotatable cylinder 432 is supported by a magnetic rotor 438, which is a cylindrical member having a ledge 440 on which the rotatable cylinder 432 rests when both members are installed in the heat treatment chamber 402. The magnetic rotor 438 has multiple magnets in a magnet area 442 below the ledge 440. The magnetic rotor 438 is located in an annular well 444 situated in the peripheral region of the heat treatment chamber 402 along the base 410. A cover 446 rests on the peripheral portion of the base 410 and extends over the annular well 444 toward the rotatable cylinder 432 and support ring 430, leaving a tolerance gap between the cover 446 and the rotatable cylinder 432 and / or support ring 430. The cover 446 generally protects the magnetic rotor 438 from exposure to the process conditions of the treatment area 406.

[0050] The magnetic rotor 438 rotates due to magnetic energy from the magnetic stator 448 positioned around the base 410. The magnetic stator 448 has several electromagnets 450 which, during processing of the substrate W, are powered according to a rotation pattern 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 454. By operating the linear actuator 452, the magnetic stator 448 moves along the axis 456 of the heat treatment chamber 402, thereby moving the magnetic rotor 438, the rotatable cylinder 432, the support ring 430, and the substrate W along the axis 456.

[0051] The processing gas is supplied to the heat treatment chamber 402 through the chamber inlet 458, oriented outward from the plane of the paper, and exhausted through the chamber outlet, which is oriented substantially coplanar with the chamber inlet 458 and the support ring 430 (not shown in Figure 4). The substrate enters and exits the heat treatment chamber 402 through an access port 460 formed in the side wall 408 and shown at the rear of Figure 4.

[0052] Figure 4 shows a single gas source 404, but additional gas sources are also possible. The gas source 404 may also be coupled to a plasma initiator (not shown) to remotely supply radicals to the process volume. The gas source 404 may be one or more of the following plasma-forming gases, including nitrogen-containing gases, oxygen-containing gases, silicon-containing gases, hydrogen-containing gases, or argon or helium, or may contain these.

[0053] Figure 5 shows a method 500 for processing a substrate according to one embodiment, which can be performed using processing systems 200 and 400. Figures 6A to 6C are schematic cross-sectional views of a portion of a substrate 600, showing aspects of method 500 at different stages of a void-free, seam-free tungsten gap-filling process scheme.

[0054] The substrate 600 features a patterned surface 601 including a dielectric material layer 602 in which a plurality of openings 605 (one shown) are formed internally. In some embodiments, the plurality of openings 605 include one or a combination of high aspect ratio via or trench openings with a width of about 1 μm or less, e.g., about 800 nm or less or about 500 nm or less, and a depth of about 2 μm or more, e.g., about 3 μm or more or about 4 μm or more. In some embodiments, the individual openings of the openings 605 may have an aspect ratio (depth-to-width ratio) of about 3:1 or more, e.g., about 5:1 or more, or 10:1 or more. In some embodiments, the via or trench openings are about 20 nm to about 50 nm and have an aspect ratio of about 3:1 to about 10:1.

[0055] As shown in the figure, the patterned surface 601 includes a barrier or adhesive layer 603, such as a titanium nitride (TiN) layer, deposited on the dielectric material layer 602 to conformally back the opening 605 and facilitate the subsequent deposition of the tungsten nucleation layer 604. In some embodiments, the adhesive layer 603 is deposited to a thickness of about 20 angstroms (Å) to about 150 Å, for example, about 30 Å to about 100 Å.

[0056] In operation 502, method 500 includes exposing a substrate having an adhesive layer 603 to a tungsten-containing precursor gas at a precursor gas flow rate. In operation 504, the substrate is exposed to a reducing agent at a reducing agent flow rate. Operations 502 and 504 are performed periodically alternately, starting with either 502 or 504. In some embodiments, operations 502 and 504 are performed periodically alternately, starting with operation 502 and ending with operation 504. Operations 502 and 504 together use a nucleation process to form a nucleation layer 604 on the substrate. The ratio of the reducing agent gas flow rate to the precursor agent flow rate is about 5:1 or greater by volume, for example, about 6:1 to about 10:1. A portion of an exemplary substrate 600 on which the nucleation layer 604 is formed is schematically shown in Figure 6A.

[0057] In some embodiments, an atomic layer deposition (ALD) process is used to deposit the nucleation layer 604. The ALD process involves alternating cycles of exposing the substrate 600 to a tungsten-containing precursor and cycles of exposing the substrate 600 to a reducing agent. In some embodiments, the process area 221 is purged between alternating exposures. In some embodiments, the process area 221 is purged continuously during operations 402 and 404. Examples of suitable 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-dicarbonyl initrosyl-tungsten), EDNOW (methylcyclopentadienyl-dicarbonyl initrosyl-tungsten), tungsten hexacarbonyl (W(CO)6), or combinations thereof.

[0058] During the nucleation process, the processing volume 215 is maintained at a pressure of less than approximately 120 Torr, such as approximately 900 mTorr to approximately 120 Torr, approximately 1 Torr to approximately 100 Torr, or for example, approximately 1 Torr to approximately 50 Torr. Exposure of the substrate 600 to the tungsten-containing precursor includes flowing the tungsten-containing precursor from the deposition gas source 240 to the processing area 221 at a flow rate of less than approximately 100 sccm, for example, approximately 10 sccm to approximately 60 sccm, or approximately 20 sccm to approximately 80 sccm. Exposure of the substrate 600 to the reducing agent includes flowing the reducing agent from the deposition gas source 240 to the processing area 221 at a flow rate of approximately 200 sccm to approximately 1000 sccm, such as approximately 300 sccm to approximately 750 sccm. The sediment gas source 240 shown in Figure 3 was found to be particularly useful for flowing gas from the reducing gas source 302 through the reservoir 306 at a gas flow rate of approximately 100 sccm or more, for example, approximately 300 sccm or more.

[0059] It should be noted that the flow rates for the various deposition and processing processes described herein are for 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.

[0060] The tungsten-containing precursor and reducing agent are each flowed into the processing area 221 for a period of approximately 0.1 to 10 seconds, for example, approximately 0.5 to 5 seconds. The processing area 221 can be purged between alternating exposures by flowing a purge gas, such as argon (Ar) or hydrogen gas, into the processing area 221 for a period of approximately 0.1 to 10 seconds, such as approximately 0.5 to 5 seconds. The purge gas may be supplied from a deposit gas source 240 or a bypass gas source 238. Typically, the repeated cycles of the nucleation process continue until the nucleation layer 604 is about 10 Å to 200 Å thick, for example, about 10 Å to 150 Å or about 20 Å to 150 Å. The nucleation layer 604 is located along the sidewalls of the opening 605, such as on top of a barrier or adhesive layer 603. The nucleation layer has a boron-to-tungsten atomic ratio of approximately 1:n, where n is approximately 5 or less, for example, approximately 1:4.5 to approximately 1:1, for example, approximately 1:4 to approximately 1:2, or approximately 1:3 to 3:4, for example, approximately 1.1:1 to approximately 2:1.

[0061] In operation 506, method 500 includes treating the nucleation layer 604 to inhibit tungsten deposition on the field surface of the substrate 600, and forming differential inhibition profiles in a plurality of openings 605 by using a differential inhibition process. Typically, forming differential inhibition profiles involves exposing the nucleation layer 604 to an active nuclide of a treatment gas, e.g., a treatment radical 606 shown in Figure 6B. Suitable treatment gases that can be used in the inhibition process include N2, H2, NH3, NH4, O2, CH4, or combinations thereof. In some embodiments, the treatment gas includes nitrogen, e.g., N2, H2, NH3, NH4, or combinations thereof, and the active nuclide includes nitrogen radicals, e.g., atomic nitrogen. In some embodiments, the treatment gas is combined with an inert carrier gas, e.g., Ar, He, or combinations thereof, to form a treatment mixed gas.

[0062] Although not bound by theory, it is thought that the active nitrogen nuclide (treated radical 606) is incorporated into a portion of the nucleation layer 604 by adsorption of the active nitrogen nuclide and / or by reaction with metallic tungsten in the nucleation layer 604, thereby forming a tungsten nitride (WN) surface. The adsorbed nitrogen and / or nitrided surface of the tungsten nucleation layer 604 preferably delay (inhibit) further tungsten nucleation and therefore delay subsequent tungsten deposition on the tungsten nucleation layer.

[0063] In some embodiments, exposing the nucleation layer 604 to the treatment radicals 606 includes using a first radical generator 206A to form a treatment plasma 282A of a substantially halogen-free treatment mixture gas and flowing the ejecta of the treatment plasma 282A into a treatment area 221. In some embodiments, the flow rate of the treatment mixture gas to the first radical generator 206A, and therefore the flow rate of the treatment plasma ejecta into the treatment area 221, is about 1 sccm to about 3000 sccm, for example, about 1 sccm to about 2500 sccm, about 1 sccm to about 2000 sccm, about 1 sccm to about 1000 sccm, about 1 sccm to about 500 sccm, about 1 sccm to about 250 sccm, about 1 sccm to about 100 sccm, or about 1 sccm to about 75 sccm, for example, about 1 sccm to about 50 sccm.

[0064] In some embodiments, the inhibition process includes exposing the substrate 600 to the treatment radical 606 for a period of about 2 seconds or more, such as about 4 seconds or more, about 6 seconds or more, about 8 seconds or more, about 9 seconds or more, or about 10 to about 20 seconds.

[0065] In some embodiments, the concentration of substantially halogen-free process gas in the process gas mixture is about 0.1% to about 50% by volume, for example, about 0.2% to about 40% by volume, about 0.2% to about 30% by volume, about 0.2% to about 20% by volume, or for example, about 0.2% to about 10% by volume, for example, about 0.2% to about 5% by volume.

[0066] In other embodiments, the processing radicals 606 can be formed using a remote plasma (not shown) ignited and maintained in a portion of the processing volume 215 separated from the processing area 221 by the showerhead 218, such as between the showerhead 218 and the lid plate 216. In these embodiments, the activated processing gas may flow through an ion filter to remove substantially all ions from the processing gas before the processing radicals 606 reach the processing area 221 and the surface of the substrate 600. In some embodiments, the showerhead 218 can be used as an ion filter. In other embodiments, the plasma used to form the processing radicals is an in-situ plasma formed in the processing area 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 of ions formed from the processing gas, such as charged processing radicals, and / or to accelerate them toward the substrate surface.

[0067] In some embodiments, the inhibition process includes flowing an activation gas into the processing volume 215 while maintaining the processing volume 215 at a pressure of less than about 100 Torr. For example, during the inhibition process, the processing volume 215 may be maintained at a pressure of less than about 75 Torr, e.g., 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, e.g., 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.

[0068] In operation 508, method 500 includes depositing tungsten gap-filling material 608 (Figure 6C) into a plurality of openings 605 according to the differential inhibition profile provided by the inhibition treatment in operation 206. In one embodiment, the tungsten gap-filling material 608 is formed using a chemical vapor deposition (CVD) process that includes simultaneously flowing (in parallel) a tungsten-containing precursor gas and a reducing agent into a processing area 221 and exposing the substrate 600 to them. The tungsten-containing precursor and reducing agent used in the tungsten gap-filling CVD process may include any combination of tungsten-containing precursor and reducing agent described with reference to operations 502 and 504. In some embodiments, the tungsten-containing precursor includes WF6 and the reducing agent includes hydrogen gas.

[0069] The tungsten-containing precursor is flowed into the processing area 221 at a flow rate of approximately 10 sccm to approximately 1000 sccm, or more than approximately 50 sccm, or less than approximately 1000 sccm, or approximately 100 sccm to approximately 900 sccm. The reducing agent is flowed into the processing area 221 at a flow rate of more than approximately 500 sccm, for example more than approximately 750 sccm, more than approximately 1000 sccm, or approximately 500 sccm to approximately 10000 sccm, for example more than 1000 sccm to approximately 9000 sccm, or more than 1000 sccm to approximately 8000 sccm.

[0070] In some embodiments, tungsten gap-filling CVD process conditions are selected to provide tungsten characteristics with relatively lower residual film stress compared to conventional tungsten CVD processes. For example, in some embodiments, the tungsten gap-filling CVD process includes heating the substrate to a temperature of about 250°C or higher, e.g., about 300°C or higher, or about 250°C to about 600°C, or about 300°C to about 500°C. During the CVD process, the processing volume 215 is typically 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 about 1 Torr to about 500 Torr, e.g., about 1 Torr to about 450 Torr, or about 1 Torr to about 400 Torr, or e.g., about 1 Torr to about 300 Torr.

[0071] In another embodiment, an atomic layer deposition (ALD) process is used to deposit the tungsten gap-filling material 608 in operation 508. The tungsten gap-filling ALD process includes repeating a cycle of alternately exposing the substrate 600 to a tungsten-containing precursor gas and a reducing agent, and purging the processing area 221 between alternating exposures.

[0072] The tungsten-containing precursor and the reducing agent are each passed through the processing area 221 for a period of approximately 0.1 seconds to approximately 10 seconds, for example, approximately 0.5 seconds to approximately 5 seconds. The processing area 221 is typically purged between alternating exposures by passing an inert purge gas, such as argon (Ar) or hydrogen, through the processing area 221 for a period of approximately 0.1 seconds to approximately 10 seconds, such as approximately 0.5 seconds to approximately 5 seconds. The purge gas may be supplied from the deposition gas source 240 or the bypass gas source 238.

[0073] In other embodiments, the tungsten gap-filling material 608 is deposited using a pulsed CVD method, which involves repeatedly exposing the substrate 600 to a tungsten-containing precursor gas and a reducing agent in alternating cycles, without purging the processing area 221. The processing conditions for the tungsten gap-filling pulsed CVD method may be the same, substantially the same, or within the same range as those described above for the tungsten gap-filling ALD process.

[0074] It has been found that forming a nucleation layer 604 with a high concentration of boron relative to tungsten reduces the film resistivity and the surface roughness of the tungsten-containing layer, while maintaining seamless or substantially seamless gap filling at various thicknesses 620, e.g., thicknesses of about 2000 Å or less, e.g., thicknesses of about 600 Å or less, e.g., thicknesses of about 200 Å to about 600 Å. 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) placed within the opening between the 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 integral structures with no interface between them. The tungsten gap-filling material 608 and the nucleation layer 604 together form a tungsten-containing layer having a resistivity of about 25 μΩ·cm or less, depending on the thickness of the tungsten-containing layer 620. The tungsten-containing layers 604 and 608 have a thickness of about 200 Å or more and a resistivity of about 20 μΩ·cm or less. In some embodiments, the tungsten-containing layers 604 and 608 have a thickness of about 200 Å to about 600 Å and a resistivity of about 17.5 μΩ·cm or less. In some embodiments, the tungsten-containing layers 604 and 608 have a thickness of about 450 Å or more, for example, about 450 Å to about 600 Å and a resistivity of about 15 μΩ·cm or less. In some embodiments, the tungsten-containing layer has a surface roughness of about 3.5 nm or less, for example, calculated by the root mean square of about 2 nm to about 3 nm.

[0075] Although not bound by theory, the increase in boron in the nucleation layer is thought to enable the growth of bulk tungsten grains in thin film regions (e.g., thicknesses of approximately 600 Å or less, such as approximately 200 Å to approximately 500 Å), reducing electron scattering at tungsten grain boundaries and resulting in reduced resistivity. The slowing of bulk tungsten growth during processing operation 506 allows for a reduction in seam size during contact filling.

[0076] In operation 510, the substrate 600 is annealed. Annealing the substrate 600 further reduces the resistivity of the substrate. In some embodiments, the substrate 600 is annealed for about 1 second to about 10 minutes, for example, about 5 seconds to about 120 seconds, for example, about 10 seconds to about 100 seconds, for example, about 30 seconds to about 60 seconds. In some embodiments, the substrate 600 is annealed at a temperature of about 600°C or higher, for example, about 700°C to about 1200°C, for example, about 800°C to about 1000°C, for example, about 850°C to about 950°C, at a chamber pressure of about 30 Torr to about 70 Torr, for example, about 50 Torr. In some embodiments, the substrate 600 is annealed in the presence of a gas containing 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 a combination thereof. In some embodiments, the gas is flowed at a volumetric flow rate of approximately 5 L / min, for example 15 L / min, or for example 10 L / min.

[0077] The annealed substrate includes a nucleation layer 604 modified by annealing. The modified nucleation layer has a boron-to-tungsten atomic ratio of about 1:n, where n is about 4 or less, for example, about 1:3 to about 1:1, or for example, about 1:2 to about 1:1. In some embodiments, the modified nucleation layer contains an atomic boron concentration of about 10% or more relative to tungsten, for example, about 2 to 3 times the amount of boron relative to tungsten, compared to the nucleation layer 604 before annealing. For example, in one embodiment, the nucleation layer before annealing has an atomic boron-to-tungsten ratio of about 1:4 to 1:5, for example, about 1:4.5, and the modified nucleation layer after annealing has a boron-to-tungsten ratio of about 1:1 to about 1:3, for example, about 1:2.

[0078] The annealed substrate includes tungsten-containing layers 604 and 608 modified by annealing. The modified tungsten-containing layers have a resistivity of about 20 μΩ·cm or less, depending on the thickness 620 of the modified tungsten-containing layer. The modified tungsten-containing layer has a resistivity of about 17 μΩ·cm or less when the thickness of the tungsten-containing layer is about 200 Å or more. In some embodiments, the modified tungsten-containing layer has a resistivity of about 10 μΩ·cm to 16 μΩ·cm when the thickness of the modified tungsten-containing layer is about 200 Å to about 600 Å. In some embodiments, the modified tungsten-containing layer has a resistivity of about 10 μΩ·cm to 14 μΩ·cm when the thickness of the tungsten-containing layer is about 450 Å or more, for example, about 450 Å to about 600 Å. In some embodiments, the tungsten-containing layer has a surface roughness of about 3.5 nm or less, calculated by the root mean square of about 2 nm to about 3 nm. In some embodiments, the resistivity of the modified tungsten-containing layer is reduced by 10% or more, for example, about 20% to about 40%, compared to the tungsten-containing layer before annealing.

[0079] While not bound by theory, it is believed that annealing the substrate 600 increases the grain size of the tungsten-containing layer structure, contributing to a decrease in resistivity. In some embodiments, the grain size of the tungsten-containing layers 604 and 608 increased by approximately 5% or more after annealing, e.g., approximately 10% to 30%, or e.g., approximately 15% to 20%, as measured by X-ray diffraction (XRD) imaging. It was further observed that the modified tungsten-containing material contained alpha-phase tungsten and substantially no beta-phase tungsten. Alpha-phase tungsten is stable and has good conductivity. It was also found that the process described herein involves incubation growth of approximately 50 Å to 300 Å, such as approximately 70 Å to 100 Å, compared to conventional SSW of approximately 1150 Å to 1250 Å.

[0080] In a typical semiconductor manufacturing scheme, after depositing tungsten gap-filling material 608 into the opening 605, a chemical mechanical polishing (CMP) process can be used to remove the overburden of tungsten material (and the barrier layer placed beneath it) from the field surface of the substrate. [Examples]

[0081] Figure 7 shows comparative curves illustrating the resistivity of film layers formed using the methods and comparative methods described herein, according to some embodiments. Curves 702, 704, 706, and 708 show the film resistivity results as a function of film thickness for each film sample. Where used herein, film resistivity is measured using ASTM B193-20(2020) with a KLA Rs-200 resistivity mapping system to measure sheet resistance with a four-point probe. Film thickness is measured using a Rigaku MFM65 in-line XRF wafer inspection system. Film resistivity is obtained by multiplying the sheet resistance by the film thickness.

[0082] Curve 702 corresponds to a film formed using a process similar to the process described herein before annealing, having a nucleation layer with a boron-to-tungsten atomic ratio of about 1:4.5 or less, e.g., about 1:4.6 to about 1:6. The sample film of curve 702 can be formed using operations 502 to 508 of Method 500. The sample film of curve 702 was formed by exposing the sample to nitrogen plasma from a remote plasma source, as described in operation 508. Curve 704 corresponds to a film deposited using a conventional CVD process. The conventional CVD process shown by curve 704 resulted in relatively low resistivity across all thickness ranges, but the film contained voids and seams within the openings, and good structural properties were not obtained. The film of curve 702 provided good gap-filling properties with substantially no voids and seams, but at film thicknesses less than 500 Å, the resistivity increased to about 20 μΩ·cm or more. Curve 706 corresponds to films formed using a conventional CVD process in which the boron concentration in the nucleation layer is increased, such as having a boron-to-tungsten atomic ratio of approximately 1:4 or higher, with the nucleation layer having a ratio of approximately 1:3 to approximately 1:2. As can be seen from the figure, the resistivity after increasing the boron concentration in nucleation of films formed using a conventional CVD process results in a decrease in film resistivity. The resistivity of thin films with a thickness of 200 Å to 600 Å does not reach a resistivity of approximately 16 μΩ·cm or less.

[0083] Curve 708 corresponds to a film formed using the processes described herein (e.g., Method 500, Operations 502-508) prior to annealing, having a nucleation layer with a boron-to-tungsten atomic ratio of approximately 1:4 or higher, such as approximately 1:3 to approximately 1:2. The film of Curve 708 was similar to the film of Curve 702, except that the film of Curve 708 contained a higher boron concentration in the nucleation layer. The film of Curve 708 provided good gap-filling properties with no or substantially no voids and seams, and also resulted in low resistivity for thicknesses less than 500 Å and greater than 500 Å. Compared to the film corresponding to Curve 702, the film corresponding to Curve 708 showed a 10-70% reduction in film resistivity for thicknesses of approximately 200 Å to approximately 2000 Å, while simultaneously suppressing gap-filling used in the post-nucleation layer processing. The reduction in film resistivity was greater for thin films than for thick films. Compared to samples formed by conventional CVD processes, samples formed using operations 502-508 of Method 500, which have a higher boron concentration in the nucleation layer, surprisingly resulted in reduced resistivity with much lower roughness and much lower resistivity.

[0084] Figure 8 shows the effect of annealing temperature on samples with a tungsten-containing layer approximately 300 Å thick. The tungsten-containing layer on each sample could be formed using operations 502–508 of Method 500 as a control, and the corresponding sample could be formed using operations 502–510 with annealing. Each pair of data points corresponds to resistivity measurements compared to an unannealed control sample at 50-degree intervals with annealing temperatures ranging from 600°C to 850°C. As can be seen from the figure, generally, higher annealing temperatures corresponded to a greater decrease in resistivity. In addition to the improvement in resistivity, the annealed films maintained low surface roughness. Although not bound by theory, as observed by microscopic imaging, grain growth appears to have occurred planarly with some increase in film thickness, rather than in rough vertical growth.

[0085] Figure 9 shows 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 502–508 of Method 500 as a control, and curve 904 includes resistivity measurements for corresponding samples formed using operations 502–510 with annealing. As can be seen from the figure, a greater effect of annealing is observed in thinner films, such as those less than 300 Å thick.

[0086] Table 1 shows a comparison of grain size before and after annealing. The first sample (s1) was formed using operations 502-508 of Method 500. The thickness of s1 before annealing was 227.7 Å and the resistivity was 45.6 μΩ·cm. The grain size was measured to be 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 the same between the first and second samples. Although not bound by theory, it is thought that the grain expansion occurred planarly, minimizing the expansion of film thickness while keeping the roughness substantially the same, as evidenced by topology imaging. As a result of grain growth, the resistivity of the second sample s2 was lower than that of the first sample.

[0087] The third sample (s3) was formed using operations 502-508 of Method 500. Before annealing, the thickness of s3 was 324.4 Å and the resistivity was 16.3 μΩ·cm. The grain size was measured to be 265 Å. The fourth sample (s4) was formed similarly to 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 the same for both the first and second samples. As a result of grain growth, the fourth sample s4 had a lower resistivity compared to the third sample. As demonstrated by the second sample compared to the first sample, it was observed that the decrease in resistivity was much greater as the film became thinner.

[0088] [Table 1]

[0089] Additional aspects This disclosure may include the following non-limiting aspects and / or embodiments.

[0090] Clause 1. A structure on a substrate, comprising an opening in the substrate, a tungsten-containing layer which is a nucleation layer disposed along the side wall of the opening and contains boron and tungsten, and a packing layer disposed on the nucleation layer in the opening which includes a packing layer which has a resistivity of about 16 μΩ·cm or less, has a thickness of about 200 Å to about 600 Å, and the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed in the opening between the opposing side wall portions of the opening.

[0091] Clause 2. The structure described in Clause 1, wherein the nucleation layer contains a boron-to-tungsten ratio of approximately 1:4 to approximately 1:1.

[0092] Clause 3. The structure described in Clause 1 or Clause 2, wherein the boron-to-tungsten ratio is approximately 1:3 to 1:2.

[0093] Clause 4. The structure according to any one of Clauses 1 to 3, further comprising an adhesive layer disposed between the substrate and the nucleation layer.

[0094] Clause 5. The structure according to any one of Clauses 1 to 4, wherein the tungsten-containing layer further comprises nitrogen, oxygen, fluorine, or a combination thereof.

[0095] Clause 6. A structure on a substrate, comprising an opening in the substrate, an adhesive layer disposed on the side wall of the opening, and a tungsten-containing layer disposed on the adhesive layer in the side wall, wherein the tungsten-containing layer has a resistivity of about 16 μΩ·cm or less, a thickness of about 200 Å to about 600 Å, and the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed in the opening between the opposing side wall portions of the opening.

[0096] Clause 7. The structure described in Clause 6, wherein the thickness of the tungsten-containing layer is approximately 300 Å to approximately 600 Å, and the resistivity of the tungsten-containing layer is approximately 14 μΩ·cm or less.

[0097] Clause 8. The structure according to Clause 6 or Clause 7, wherein the tungsten-containing layer comprises a boron-containing nucleation layer.

[0098] Clause 9. A structure according to any one of Clauses 6 to 8, wherein the boron-to-tungsten ratio is approximately 1:3 to 1:1.

[0099] Clause 10. The structure according to any one of Clauses 6 to 9, wherein the tungsten-containing layer has a surface roughness calculated by the root mean square of approximately 3.5 nm or less.

[0100] Clause 11. The structure according to any one of Clauses 6 to 10, wherein the tungsten-containing layer has a surface roughness calculated by the root mean square of approximately 2 nm to approximately 3 nm.

[0101] Clause 12. A method for forming a structure on a substrate, comprising: exposing the substrate to a tungsten-containing precursor gas at a precursor gas flow rate; exposing the substrate to a boron-containing reducing agent at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are applied periodically and alternately to form a nucleation layer on the substrate within at least one opening of the substrate; depositing a packed layer on the nucleation layer within at least one opening; and annealing the substrate at about 600°C to about 1000°C.

[0102] Clause 13. The method according to Clause 12, further comprising transferring the substrate to a rapid heat treatment chamber before annealing.

[0103] Clause 14. The method of Clause 12 or Clause 13, wherein annealing the substrate includes exposing the substrate to hydrogen gas.

[0104] Clause 15. The method described in any one of Clauses 12 to 14, wherein the reducing agent flow rate is approximately 300 sccm or more.

[0105] Clause 16. The method described in any one of Clauses 12 to 15, wherein the precursor gas flow rate is approximately 60 sccm or less.

[0106] Clause 17. The method according to any one of Clauses 12 to 16, further comprising filling a reservoir with a reducing agent using a reservoir valve located upstream of the reservoir, and flowing the reducing agent from the reservoir into a process volume containing the substrate by opening a mass flow control valve located between the process volume and the reservoir.

[0107] Clause 18. The method according to any one of Clauses 12 to 17, further comprising filling the reservoir by opening the reservoir valve when the pressure in the reservoir falls below a predetermined pressure.

[0108] Clause 19. The method described in any one of Clauses 12 to 18, wherein the substrate is annealed for approximately 1 second to approximately 10 minutes.

[0109] Clause 20. The method according to Clause 19, wherein the substrate is annealed for approximately 10 to 60 seconds.

[0110] Clause 21. The method according to any one of Clauses 12 to 20, wherein annealing the substrate involves passing a gas selected from the group consisting of nitrogen-containing gas, argon-containing gas, hydrogen-containing gas, or a combination thereof over the substrate.

[0111] Clause 22. The method according to any one of Clauses 12 to 21, wherein the substrate is annealed from a plurality of heating lamps positioned above the substrate.

[0112] Clause 23. The method according to any one of Clauses 12 to 22, wherein the substrate is annealed at a temperature of approximately 700°C to approximately 900°C.

[0113] Clause 24. The method according to any one of Clauses 12 to 23, wherein the ratio of reducing agent gas flow rate to precursor agent flow rate is m:1, and m is approximately 5 or more by volume.

[0114] Clause 25. A method for forming a structure on a substrate, comprising: exposing the substrate to a tungsten-containing precursor gas at a precursor gas flow rate; exposing the substrate to a boron-containing reducing agent at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are applied periodically and alternately to form a nucleation layer on the substrate within at least one opening of the substrate; depositing a packing layer on the nucleation layer within at least one opening, wherein the packing 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.

[0115] Clause 26. The method according to Clause 25, wherein the second resistivity is approximately 10% to 50% lower than the first resistivity.

[0116] While the above applies to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.

Claims

1. A structure on a substrate, The opening in the substrate, A tungsten-containing layer, A nucleation layer arranged along the side wall of the opening, containing a boron-to-tungsten ratio of approximately 1:3 to approximately 1:2, and A packing layer disposed on the nucleation layer within the opening, wherein the tungsten-containing layer has a resistivity of about 16 μΩ·cm or less, the tungsten-containing layer has a thickness of about 200 Å to about 600 Å, and the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between the opposing side wall portions of the opening. A tungsten-containing layer including A structure that includes this.

2. The structure according to claim 1, wherein the boron-to-tungsten ratio is approximately 1:3 to 1:

2.

3. The structure according to claim 1, further comprising an adhesive layer disposed between the substrate and the nucleation layer.

4. The structure according to claim 1, wherein the tungsten-containing layer further comprises nitrogen, oxygen, fluorine, or a combination thereof.

5. A structure on a substrate, The opening in the substrate, An adhesive layer is placed on the side wall of the opening, A tungsten-containing layer disposed on the adhesive layer within the side wall, wherein the tungsten-containing layer has a resistivity of about 16 μΩ·cm or less, a thickness of about 200 Å to about 600 Å, and the thickness of the tungsten-containing layer is half the width of the tungsten-containing layer disposed within the opening between the opposing side wall portions of the opening. Includes, A structure comprising a tungsten-containing layer which includes a nucleation layer arranged along the side wall of the opening, and which contains boron having a boron-to-tungsten ratio of about 1:3 to about 1:

2.

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

7. The structure according to claim 5, wherein the tungsten-containing layer has a surface roughness calculated by the root mean square of approximately 3.5 nm or less.

8. The structure according to claim 5, wherein the tungsten-containing layer has a surface roughness calculated by the root mean square of approximately 2 nm to approximately 3 nm.

9. A method for forming a structure on a substrate, The substrate is exposed to a tungsten-containing precursor gas at a precursor gas flow rate, The substrate is exposed to a reducing agent containing boron at a reducing agent flow rate, and the tungsten-containing precursor gas and the reducing agent are applied periodically and alternately to form a nucleation layer on the substrate within at least one opening of the substrate, and the nucleation layer contains a boron-to-tungsten ratio of about 1:3 to about 1:2 during the exposure. A packing layer is deposited on the nucleation layer within the at least one opening, The substrate is annealed at approximately 600°C to approximately 1000°C. Includes, A method comprising a tungsten-containing layer including the nucleation layer and the packed layer having a resistivity of about 16 μΩ·cm or less and a thickness of about 200 Å to about 600 Å.

10. The method according to claim 9, further comprising transferring the substrate to a rapid heat treatment chamber before annealing.

11. The method according to claim 9, wherein annealing the substrate includes exposing the substrate to hydrogen gas.

12. The method according to claim 9, wherein the flow rate of the reducing agent is approximately 300 sccm or more.

13. The method according to claim 9, wherein the precursor gas flow rate is approximately 60 sccm or less.

14. The method according to claim 9, further comprising filling a reservoir with the reducing agent using a reservoir valve located upstream of the reservoir, and flowing the reducing agent from the reservoir to a process volume containing the substrate by opening a mass flow control valve located between the process volume and the reservoir.

15. The method according to claim 14, further comprising filling the reservoir by opening the reservoir valve when the pressure in the reservoir falls below a predetermined pressure.

16. The method according to claim 9, wherein the substrate is annealed for about 1 second to about 10 minutes.

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

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