Methods to minimize gap filling height variations between features

Abstract

A method for gap-filling features on a substrate reduces gap-fill height variation between features by using a tungsten halide soaking treatment. In some embodiments, the method may include the steps of heating the substrate to a temperature of approximately 350 degrees Celsius to approximately 450 degrees Celsius, exposing the substrate to a tungsten halide gas at a process pressure of approximately 5 Torr to approximately 25 Torr, soaking the substrate with the tungsten halide gas for a soaking time of approximately 5 seconds to approximately 60 seconds, and, after the soaking of the substrate is completed, performing a metal pre-cleaning process and gap-filling deposition on a plurality of features on the substrate.

Description

Technology Field

[0001] The embodiments of the principles of the present invention generally relate to semiconductor processing of semiconductor substrates. Background Technology

[0002] While depositing gap-filling materials on features such as vias and trenches, not all features reach the same gap-filling height. Contaminants on the surfaces of the seed layers at the bottom of the features, along with contaminants on the sidewalls of the features, often cause irregular filling of the features. Some features may have low filling heights, others may have sloped top filling surfaces, and still others may have irregular top filling surfaces. All of these defects cause large feature-to-feature gap-filling height variations, which leads to problematic processing during subsequent workflows and often results in poor feature performance, such as high contact resistance.

[0003] Accordingly, the inventors have provided improved processes that minimize variations between features with high throughput and increased feature performance.

[0004] Methods and apparatus for minimizing gap filling height variations between features for gap filling of features are provided herein.

[0005] In some embodiments, a method for gap-filling features on a substrate may include the steps of heating the substrate to a temperature of approximately 350 degrees to approximately 450 degrees; exposing the substrate to a tungsten halide gas at a process pressure of approximately 5 Torr to approximately 25 Torr; soaking the substrate with the tungsten halide gas for a soaking time of approximately 5 seconds to approximately 60 seconds; and, after the soaking time has elapsed, performing a metal pre-cleaning process and a gap-filling deposition on a plurality of features on the substrate.

[0006] In some embodiments, the method comprises the steps of flowing a tungsten halide gas at a flow rate of approximately 400 sccm — the tungsten halide gas is tungsten hexafluoride gas (WF6), tungsten pentachloride gas (WCl5), or tungsten hexachloride gas (WCl6) — exposing a substrate to a gas mixture of tungsten halide gas and hydrogen gas — the hydrogen gas has a flow rate greater than 0 to approximately 6000 sccm, the tungsten halide gas has a flow rate of 400 sccm, the hydrogen gas has a flow rate of approximately 400 sccm to approximately 3000 sccm, the soaking time is approximately 10 seconds, the process pressure is 10 Torr, and the temperature is approximately 350 degrees Celsius, the hydrogen gas has a flow rate of approximately 3000 sccm, the tungsten halide gas has a flow rate of 400 sccm, and the soaking time is approximately The process pressure is 10 seconds, the process pressure is 10 Torr, and the temperature is approximately 400 degrees Celsius, and the gap filling height between features of a plurality of features on the substrate has a variation of less than 9 nm — and / or may further include the step of performing oxygen treatment on the substrate before soaking the substrate.

[0007] In some embodiments, a method for gap-filling features on a substrate may include the steps of heating the substrate to a temperature of approximately 350 degrees to approximately 450 degrees, exposing the substrate to tungsten hexafluoride gas (WF6) at a process pressure of approximately 10 Torr, soaking the substrate with tungsten hexafluoride gas for a soaking time of approximately 10 seconds, and, after the soaking time has elapsed, performing a metal pre-cleaning process and gap-filling deposition on a plurality of features on the substrate.

[0008] In some embodiments, the method further comprises the steps of flowing tungsten hexafluoride gas (WF6) at a flow rate of approximately 400 sccm, exposing a substrate to a gas mixture of tungsten hexafluoride gas (WF6) and hydrogen gas, wherein the hydrogen gas has a flow rate greater than 0 to approximately 6000 sccm, the tungsten hexafluoride gas (WF6) has a flow rate of 400 sccm, the hydrogen gas has a flow rate of approximately 400 sccm to approximately 3000 sccm, and the temperature is approximately 350 degrees Celsius, the hydrogen gas has a flow rate of approximately 3000 sccm, the tungsten hexafluoride gas (WF6) has a flow rate of 400 sccm, and the temperature is approximately 400 degrees Celsius, and / or the feature-to-feature gap filling height of a plurality of features on the substrate has a variation of less than 9 nm.

[0009] In some embodiments, a non-transient computer-readable medium storing instructions is disclosed, the instructions, when executed, cause a method of gap-filling features to be performed, the method may include the steps of heating a substrate to a temperature of approximately 350 degrees Celsius to approximately 450 degrees Celsius, exposing the substrate to a tungsten halide gas at a process pressure of approximately 5 Torr to approximately 25 Torr, soaking the substrate with the tungsten halide gas for a soaking time of approximately 5 seconds to approximately 60 seconds, and, after the soaking time has elapsed, performing a metal pre-cleaning process and a gap-filling deposition on a plurality of features on the substrate, wherein the variation in gap-filling height between features of the plurality of features on the substrate is less than 9 nm.

[0010] In some embodiments, a method of a non-transient computer-readable medium may further comprise the step of exposing a substrate to a gas mixture of tungsten halide gas and hydrogen gas — where the tungsten halide gas has a flow rate of 400 sccm and the hydrogen gas has a flow rate greater than 0 to approximately 6000 sccm —, the step of exposing the substrate to a gas mixture of tungsten halide gas and hydrogen gas — where the hydrogen gas has a flow rate of approximately 400 sccm to approximately 3000 sccm, the soaking time is approximately 10 seconds, the process pressure is 10 Torr, and the temperature is approximately 350 degrees Celsius — and / or the step of exposing the substrate to a gas mixture of tungsten halide gas and hydrogen gas, where the tungsten halide gas has a flow rate of 400 sccm, the soaking time is approximately 10 seconds, the process pressure is 10 Torr, and the temperature is approximately 400 degrees Celsius.

[0011] Other and additional embodiments are disclosed below. Brief explanation of the drawing

[0012] Embodiments of the principles described above, briefly summarized and discussed in more detail below, may be understood by referring to exemplary embodiments of the principles illustrated in the accompanying drawings. However, the accompanying drawings are merely illustrative of typical embodiments of the principles and should not be construed as limiting in scope, as the principles may allow for other equally valid embodiments.

[0013] FIG. 1 illustrates a schematic diagram of a process chamber according to some embodiments of the principles of the present invention.

[0014] FIG. 2 is a method for gap-filling features on a substrate according to some embodiments of the principles of the present invention.

[0015] FIG. 3 illustrates a cross-sectional view of a via on a substrate before processing according to some embodiments of the principles of the present invention.

[0016] FIG. 4 illustrates a cross-sectional view of a via on a substrate after processing according to some embodiments of the principles of the present invention.

[0017] FIG. 5 illustrates cross-sectional views of unprocessed feature-to-feature gap filling height variation and processed feature-to-feature gap filling height variation according to some embodiments of the principles of the present invention.

[0018] FIG. 6 illustrates a plan view of an integrated tool according to some embodiments of the principles of the present invention.

[0019] For ease of understanding, the same reference numbers have been used where possible to designate identical elements common to the drawings. The drawings are not drawn to actual scale and may be simplified for clarity. The elements and features of one embodiment may be advantageously incorporated into other embodiments without further mention. Specific details for implementing the invention

[0020] The methods provide additional processes compatible with current approaches to further suppress selectivity losses and mitigate inter-feature gap fill height variations, while also meeting thermal budgets. The enhanced processes have at least a one-order-magnitude reduction in inter-feature gap fill height variations compared to the 10-20 nm variations of conventional processes. The methods of the principles of the present invention can generate inter-feature gap fill height variations of only a few nanometers or less. The techniques also provide extensive process window tuning of parameters, including gas combinations, pressure, temperature, and duration, while bringing about significant improvements in suppressing field selectivity losses and ensuring similar process performance.

[0021] Although conventional approaches to gap filling have been widely used in the semiconductor industry, large discrepancies in gap filling heights between features still cause poor performance and high contact resistance (Rc) of features such as vias and trenches, resulting in low yields. Conventional approaches to metal pre-cleaning and deposition cannot remove etching residues on feature aspects, such as via or trench sidewalls, leading to long incubation, loss of selectivity, and consequently large variations in gap filling height between features. The methods of the present principles utilize selective oxygen plasma cleaning and tungsten halide (e.g., WF6, WCl5, WCl6, etc.) soaking prior to conventional metal pre-cleaning processes. The methods can be performed at temperatures ranging from approximately 350°C to approximately 450°C while preserving thermal budgets. To further reduce process temperatures while maintaining performance, hydrogen gas may be introduced along with the tungsten halide.

[0022] The methods disclosed herein may be used in any chamber that provides gases for soaking along with temperature and pressure control. In some embodiments involving oxygen-based treatments, an additional chamber may be used to apply treatment to the substrate before soaking the substrate with tungsten halide, etc. (e.g., see the integrated tool in FIG. 6). FIG. 1 shows a view (100) of a process chamber (102) according to some embodiments. The process chamber (102) includes a substrate support (122) that holds an electrostatic chuck (ESC) (110), and a shielding portion (114) that surrounds a processing volume (118). A showerhead (104) provides process gas or gases into the processing volume (118) from a gas supply portion (108) through a gas supply conduit (106). The process gas flow rate is controlled by a gas flow valve (144). In some embodiments, the process gas may be supplied at a flow rate of approximately 400 sccm. In some embodiments, an optional gas supply conduit (152) may supply optional process gas from an optional gas supply unit (150). The optional process gas flow rate is controlled by a second gas flow valve (154). In some embodiments, the optional process gas may be supplied at a flow rate greater than 0 to approximately 6000 sccm. Contaminants or unwanted gases are removed from the process chamber (102) by a pump (120). The pump (120) may also be used to maintain the process pressure within the process chamber (102). In some embodiments, the process pressure may be approximately 5 Torr to approximately 25 Torr. The process chamber (102) may also have thermal control elements or channels (142) that enable temperature control of the substrate (112) during processing by a temperature controller (140). In some embodiments, the process temperature may be approximately 350 degrees Celsius to approximately 450 degrees Celsius.

[0023] The controller (130) controls the operation of the process chamber (102) by using direct control of the process chamber (102), or alternatively, by controlling computers (or controllers) associated with the process chamber (102). During operation, the controller (130) enables data collection and feedback from individual systems to optimize the performance of the process chamber (102). The controller (130) generally includes a CPU (Central Processing Unit) (132), memory (134), and support circuitry (136). The CPU (132) may be any type of general-purpose computer processor that can be used in an industrial setting. Support circuitry (136) is typically coupled to the CPU (132) and may include a cache, clock circuits, input / output subsystems, power supply units, etc. Software routines such as the method described herein may be stored in memory (134) and, when executed by the CPU (132), may convert the CPU (132) into a specific purpose computer (controller (130)). Software routines may also be stored and / or executed by a second controller (not shown) located remotely from the process chamber (102). In some embodiments, the use of plasma may be included to enable the substrate to be exposed to an oxygen-rich environment during an optional oxygen-based process. The optional oxygen-based process may also assist in a higher rate of gap filling and, together with temperature, pressure, flow rates, and gas combinations, provide another knob for tuning gap filling height variations between features.

[0024] Memory (134) is in the form of computer-readable storage media containing instructions to enable the operation of semiconductor processes and equipment when executed by the CPU (132). The instructions in memory (134) are in the form of a program product, such as a program that implements the methods of the principles of the present invention. The program code may follow any one of a number of different programming languages. In one example, the present disclosure may be implemented as a program product stored on computer-readable storage media for use with a computer system. The program(s) of the program product define the functions of the aspects (including the methods described herein). Exemplary computer-readable storage media include: non-writable storage media in which information is permanently stored (e.g., read-only memory devices in a computer, such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory); and includes writable storage media in which changeable information is stored (e.g., floppy disks in a hard disk drive or diskette drive or any type of solid-state random access semiconductor memory) (but is not limited thereto). Such computer-readable storage media are aspects of the principles of the present invention if they have computer-readable instructions directing the functions of the methods described herein.

[0025] FIG. 2 is a method (200) for gap-filling a feature on a substrate according to some embodiments. In block (202), an optional oxygen-based treatment may be performed on the substrate. An optional oxygen-based treatment may be used when contaminated tungsten material needs to be removed before subsequent soaking of the substrate. FIG. 3 illustrates a view (300) of a via (306) formed in a dielectric layer (312) on a substrate (302) before any treatment according to some embodiments. The via (306) is used as an exemplary feature and is not intended to be limiting, as the methods disclosed herein may also be used for other features, such as trenches, etc. The via (306) has sidewalls (314) and a seed layer (304) of tungsten material at the bottom. After etching the via (306), remnants (310), such as dangling bonds and other etching residues, may remain on the sidewalls (314). Particles (308), such as tungsten trioxide etching residues, may also be found on the sidewalls (314). In some cases, the particles (308) may be tungsten material that is removed by performing an optional oxygen-based treatment of the block (202). An optional oxygen-based treatment exposes the substrate (302) to an oxygen-rich environment, the oxygen-rich environment including the formation of oxygen modifications by plasma and other means to generate oxygen ions interacting with the tungsten material from oxygen gas (O2) or ozone (O3), etc., which can convert the tungsten material into tungsten oxides, and the tungsten oxides can then be removed by tungsten halide soaking treatment.

[0026] In block (204), the substrate (302) is heated to a temperature of approximately 350 degrees Celsius to approximately 450 degrees Celsius. The temperatures may be adjusted based on the acceptable thermal budget of other structures found on the substrate (302) being processed. Higher temperatures yield better results in reducing gap-fill height variations between features. In block (206), the substrate is exposed to a tungsten halide gas at a process pressure of approximately 5 Torr to approximately 25 Torr. In some embodiments, the tungsten halide gas may be WF6, WCl5, or WCl6, etc., with a flow rate of approximately 400 sccm. In some embodiments, an optional process gas, such as hydrogen gas, may be flowed with the tungsten halide gas at a flow rate greater than 0 to approximately 6000 sccm to enable lower temperature soaking of the substrate. In some embodiments, the process pressure may be approximately 10 Torr. In block (208), the substrate (302) is soaked with tungsten halide gas, or tungsten halide gas and an optional process gas, such as hydrogen gas, for a soaking time of approximately 5 seconds to approximately 60 seconds. In some embodiments, the soaking time is approximately 5 seconds to approximately 30 seconds. In some embodiments, the soaking time is approximately 10 seconds.

[0027] FIG. 4 illustrates a view (400) of a via (306) on a substrate (302) after processing according to some embodiments. Residues (310), including dangling bonds or other etching residues, were removed along with particles (308), such as tungsten trioxide etching residues. The residues (310) and particles (308) now cause gap filling and selectivity issues that are no longer a problem, thereby ensuring high-quality gap fillings and reduced inter-feature gap filling height variation. In some embodiments, the inter-feature gap filling height variation is less than 9 nm. In some embodiments, the inter-feature gap filling height variation is approximately less than 8 nm. In some embodiments, the inter-feature gap filling height variation is approximately less than 2 nm. Smaller inter-feature gap filling height variation enables better control of gap filling and height to ensure complete gap filling for the top surface of the substrate. Higher gap fill heights also reduce the amount of material used to compensate for lower gap fill heights, which leads to increased contact resistance of the features. Low variation offers the benefits of tighter gap fill height control, increased performance, and lower contact resistance. In the same regard, low variation is also beneficial during subsequent chemical mechanical polishing processes due to less overburden.

[0028] In some embodiments, the substrate is soaked for approximately 10 seconds at a temperature of approximately 350°C to approximately 450°C and a process pressure of approximately 5 Torr to approximately 25 Torr, with a WF6 flow rate of approximately 400 sccm and a hydrogen gas flow rate of 0 to approximately 6000 sccm. In some embodiments, the substrate is soaked for approximately 10 seconds at a temperature of approximately 350°C and a process pressure of approximately 10 Torr, with a WF6 flow rate of approximately 400 sccm and a hydrogen gas flow rate of approximately 400 sccm to approximately 3000 sccm. In some embodiments, the substrate is soaked for approximately 10 seconds at a temperature of approximately 400°C and a process pressure of approximately 10 Torr, with a WF6 flow rate of approximately 400 sccm. In some embodiments, the substrate is soaked for approximately 10 seconds at a temperature of approximately 350 degrees Celsius and a process pressure of approximately 10 Torr, with a WF6 flow rate of approximately 400 sccm and a hydrogen gas flow rate of approximately 3000 sccm.

[0029] In block (210), after the soaking time has elapsed, a metal pre-cleaning process and a gap-filling deposition process are performed on a plurality of features. The metal pre-cleaning process enables the removal of any contaminants, such as oxides, from the seed layers to allow growth on the seed layers. A gap-filling deposition process is performed, resulting in a significant reduction in the gap-filling height variation between features on the substrate. FIG. 5 illustrates views of the gap-filling height variation between untreated features and the gap-filling height variation between treated features according to some embodiments. In view (500A), the substrate (302) is not treated by the methods of the present invention. After gap filling, the features (502A) are left with various gap-filling heights, and the surfaces are irregular. The untreated gap-filling height variation (504A) is large and difficult to determine accurately due to the irregular top surfaces of the gap-filling material. Additionally, the selectivity of the tungsten deposition material is reduced compared to the dielectric material, leaving tungsten field deposits (506) and tungsten sidewall deposits (508), which significantly reduce the performance of the feature and result in defects leading to reduced yields. In view (500B), the substrate (302) has undergone processing according to the methods of the present invention. After gap filling, the features (502B) have very similar gap filling heights and more uniform surfaces than the unprocessed features. The variation in the processed gap filling height (504B) is significantly smaller than the variation in the unprocessed gap filling height (504A). Furthermore, the selectivity of the tungsten deposition material is improved compared to the dielectric material because there are no tungsten field deposits or tungsten sidewall deposits, which significantly increases the performance of the feature and increases yields by reducing defects. The methods of the present invention also have the advantage of being integrated into existing workflows without significantly affecting throughput due to the use of common process chambers and short processing times.

[0030] FIG. 6 illustrates a view of an integrated tool (600) according to some embodiments. The integrated tool (600) enables optional oxygen-based treatment, tungsten halide soaking treatment, metal pre-cleaning, and gap-filling deposition processes to be completed in a single tool. Accordingly, the methods described herein may be performed in individual process chambers that may be provided as part of a cluster tool, e.g., the integrated tool (600) described below with respect to FIG. 6 (i.e., cluster tool), or as a standalone configuration. An advantage of using the integrated tool (600) is that there is no vacuum break. However, the methods described herein may be performed using other cluster tools having suitable process chambers, or in other suitable independent process chambers. The integrated tool (600) includes a vacuum-tight processing platform (601), a factory interface (604), and a system controller (602). The processing platform (601) includes a plurality of processing chambers, such as 614A, 614B, 614C, 614D, 614E, 614F, and 614G, which are operably coupled to a vacuum substrate transfer chamber (transfer chambers (603A, 603B)). The factory interface (604) is operably coupled to the transfer chamber (603A) by one or more load lock chambers (two load lock chambers such as 606A and 606B shown in FIG. 6).

[0031] In some embodiments, the factory interface (604) includes at least one docking station (607) and at least one factory interface robot (638) for enabling the transfer of semiconductor substrates. The docking station (607) is configured to accommodate one or more front opening unified pods (FOUPs). Three FOUPs, such as 605A, 605B, and 605C, are illustrated in the embodiment of FIG. 6. The factory interface robot (638) is configured to transfer substrates from the factory interface (604) to a processing platform (601) through load lock chambers, such as 606A and 606B. Each of the load lock chambers (606A and 606B) has a first port coupled to the factory interface (604) and a second port coupled to the transfer chamber (603A). The load lock chambers (606A and 606B) are coupled to a pressure control system (not shown), which pumps down and ventilates the load lock chambers (606A and 606B) to enable the passage of substrates between the vacuum environment of the transfer chamber (603A) and the substantially ambient (e.g., atmospheric) environment of the factory interface (604). The transfer chambers (603A, 603B) have vacuum robots (642A, 642B) placed in each of the individual transfer chambers (603A, 603B). The vacuum robot (642A) can transport substrates (621) between the load lock chambers (606A, 606B), the processing chambers (614A and 614F), and the cooling station (640) or pre-cleaning station (642). The vacuum robot (642B) can transport substrates (621) between the cooling station (640) or pre-cleaning station (642) and the processing chambers (614B, 614C, 614D, 614E, and 614G).

[0032] In some embodiments, processing chambers (614A, 614B, 614C, 614D, 614E, 614F, and 614G) are coupled to transfer chambers (603A, 603B). The processing chambers (614A, 614B, 614C, 614D, 614E, 614F, and 614G) include at least an atomic layer deposition (ALD) process chamber and a chemical vapor deposition (CVD) process chamber. Additional chambers such as physical vapor deposition (PVD) chambers, annealing chambers, additional ALD chambers, additional PVD chambers, optional oxygen-based processing chambers, etc., may also be provided. The ALD and CVD chambers may include any chambers suitable for carrying out all or part of the methods described herein, as discussed above. In some embodiments, one or more optional service chambers (shown as 616A and 616B) may be coupled to the transfer chamber (603A). The service chambers (616A and 616B) may be configured to perform other substrate processes, such as degassing, orientation, substrate metrology, cooling, etc.

[0033] The system controller (602) controls the operation of the tool (600) by using direct control of the process chambers (614A, 614B, 614C, 614D, 614E, 614F, and 614G), or alternatively by controlling computers (or controllers) associated with the process chambers (614A, 614B, 614C, 614D, 614E, 614F, and 614G) and the tool (600). During operation, the system controller (602) enables data collection and feedback from the individual chambers and systems to optimize the performance of the tool (600). The system controller (602) generally includes a CPU (Central Processing Unit) (630), memory (634), and support circuitry (632). The CPU (630) may be any type of general-purpose computer processor that can be used in an industrial setting. The support circuit (632) is typically coupled to the CPU (630) and may include a cache, clock circuits, input / output subsystems, power supply units, etc. Software routines such as those described above may be stored in memory (634) and, when executed by the CPU (630), may convert the CPU (630) into a specific purpose computer (system controller) (602). Software routines may also be stored and / or executed by a second controller (not shown) located remotely from the tool (600).

[0034] Embodiments according to the principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more computer-readable media, and such instructions may be read and executed by one or more processors. A computer-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a "virtual machine" running on one or more computing platforms). For example, a computer-readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, computer-readable media may include non-transient computer-readable media.

[0035] Although the foregoing relates to embodiments of the principles of the present invention, other and additional embodiments of the principles of the present invention may be devised without departing from the basic scope of the present disclosure.

Claims

Claim 1 A method for gap-filling features on a substrate, comprising: a step of heating a substrate having a seed layer of tungsten material at the bottom of the features to a temperature of 350 to 450 degrees Celsius; a step of exposing the substrate to a tungsten halide gas at a process pressure of 5 to 25 Torr; a step of soaking the substrate with the tungsten halide gas for a soaking time of 5 to 60 seconds; and a step of performing a metal pre-cleaning process and a gap-filling deposition for a plurality of features on the substrate after the soaking time has elapsed, for removing contaminants including oxides from the seed layer to allow growth on the seed layer. Claim 2 A method for gap-filling a feature on a substrate according to claim 1, wherein the tungsten halide gas is tungsten hexafluoride gas (WF6), tungsten pentachloride gas (WCl5), or tungsten hexachloride gas (WCl6). Claim 3 A method for gap-filling features on a substrate according to claim 1, further comprising the step of flowing the tungsten halide gas at a flow rate of 400 sccm. Claim 4 A method for gap-filling features on a substrate according to claim 1, further comprising the step of exposing the substrate to a gas mixture of the tungsten halide gas and hydrogen gas. Claim 5 A method for gap-filling a feature on a substrate, wherein, in claim 4, the hydrogen gas has a flow rate of greater than 0 to 6000 sccm. Claim 6 A method for gap-filling a feature on a substrate according to claim 5, wherein the tungsten halide gas has a flow rate of 400 sccm, the hydrogen gas has a flow rate of 400 sccm to 3000 sccm, the soaking time is 10 seconds, the process pressure is 10 Torr, and the temperature is 350 degrees Celsius. Claim 7 A method for gap-filling features on a substrate, wherein the hydrogen gas has a flow rate of 3000 sccm in claim 6. Claim 8 A method for gap-filling a feature on a substrate according to claim 1, wherein the tungsten halide gas has a flow rate of 400 sccm, the soaking time is 10 seconds, the process pressure is 10 Torr, and the temperature is 400 degrees Celsius. Claim 9 A method for gap-filling features on a substrate according to claim 1, wherein the feature-to-feature gap-filling height of the plurality of features on the substrate has a variation of less than 9 nm. Claim 10 A method for gap-filling features on a substrate according to claim 1, further comprising the step of performing an oxygen treatment on the substrate before soaking the substrate. Claim 11 A method for gap-filling features on a substrate, comprising the steps of: heating a substrate having a seed layer of tungsten material at the bottom of the features to a temperature of 350 to 450 degrees Celsius; exposing the substrate to tungsten hexafluoride gas (WF6) at a process pressure of 10 Torr; soaking the substrate with the tungsten hexafluoride gas for a soaking time of 10 seconds; and, after the soaking time has elapsed, for a plurality of features on the substrate, performing a pre-cleaning process to remove contaminants including oxides from the seed layer to allow growth on the seed layer, and performing a gap-filling deposition. Claim 12 A method for gap-filling a feature on a substrate according to claim 11, further comprising the step of flowing the tungsten hexafluoride gas (WF6) at a flow rate of 400 sccm. Claim 13 A method for gap-filling features on a substrate according to claim 11, further comprising the step of exposing the substrate to a gas mixture of tungsten hexafluoride gas (WF6) and hydrogen gas. Claim 14 A method for gap-filling a feature on a substrate, wherein, in claim 13, the hydrogen gas has a flow rate of greater than 0 to 6000 sccm. Claim 15 A method for gap-filling a feature on a substrate according to claim 14, wherein the tungsten hexafluoride gas (WF6) has a flow rate of 400 sccm, the hydrogen gas has a flow rate of 400 sccm to 3000 sccm, and the temperature is 350 degrees Celsius. Claim 16 A method for gap-filling features on a substrate, wherein the hydrogen gas has a flow rate of 3000 sccm in claim 15. Claim 17 A method for gap-filling a feature on a substrate, wherein, in claim 11, the tungsten hexafluoride gas (WF6) has a flow rate of 400 sccm and the temperature is 400 degrees Celsius. Claim 18 A method for gap-filling features on a substrate according to claim 11, wherein the gap-filling height between features of the plurality of features on the substrate has a variation of less than 9 nm. Claim 19 A non-transient computer-readable medium having stored instructions, wherein, when executed, the instructions cause a method for gap-filling a feature to be performed, the method comprising: heating a substrate having a seed layer of tungsten material at the bottom of the feature to a temperature of 350 to 450 degrees Celsius; exposing the substrate to a tungsten halide gas at a process pressure of 5 to 25 Torr; soaking the substrate with the tungsten halide gas for a soaking time of 5 to 60 seconds; and, after the soaking time has elapsed, for a plurality of features on the substrate, performing a metal pre-cleaning process and gap-filling deposition to remove contaminants including oxides from the seed layer to allow growth on the seed layer, wherein the variation in gap-filling height between features of the plurality of features on the substrate is less than 9 nm. Claim 20 In claim 19, the method comprises: a step of exposing the substrate to a gas mixture of the tungsten halide gas and hydrogen gas — wherein the tungsten halide gas has a flow rate of 400 sccm and the hydrogen gas has a flow rate greater than 0 to 6000 sccm —; a step of exposing the substrate to the gas mixture of the tungsten halide gas and hydrogen gas — wherein the hydrogen gas has a flow rate of 400 sccm to 3000 sccm, the soaking time is 10 seconds, the process pressure is 10 Torr, and the temperature is 350 degrees Celsius —; A non-transient computer-readable medium further comprising the step of exposing the substrate to a gas mixture of the tungsten halide gas and hydrogen gas — wherein the tungsten halide gas has a flow rate of 400 sccm, the soaking time is 10 seconds, the process pressure is 10 Torr, and the temperature is 400 degrees Celsius.

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