KR20160140448A - Deposition of low fluorine tungsten by sequential cvd process - Google Patents

Abstract

The present invention relates to a method of deposition of low fluorine tungsten by a sequential CVD process, for example, by alternately pulsing tungsten hexafluoride and hydrogen gas in a cycle of temporally divided pulses. Partial methods include a step of deposing bulk tungsten by the sequential CVD process so as to form tungsten films with low stress having low fluorine composition after a step of deposing a tungsten nucleation layer at low pressure. Methods described on the specification can be performed by combining a non-sequential CVD deposition method and a fluorine-free tungsten deposition method.

Description

[0001] DEPOSITION OF LOW FLUORINE TUNGSTEN BY SEQUENTIAL CVD PROCESS [0002]

Deposition of tungsten-containing materials is an important part of many semiconductor manufacturing processes. These materials may be used for horizontal interconnections, vias between adjacent metal layers, contacts between the metal layers and devices on the silicon substrate, and high aspect ratio features. In a typical tungsten deposition process for a semiconductor substrate, the substrate is heated to the process temperature in a vacuum chamber and a very thin portion of the tungsten film is deposited which serves as a seed or nucleation layer. Thereafter, the remaining tungsten film (bulk layer) is deposited on the nucleation layer by simultaneously exposing the substrate to the two reactants. The bulk layer is generally deposited faster than the nucleation layer. However, as devices shrink and more complex patterning schemes are utilized in the industry, deposition of thin tungsten films becomes problematic.

Methods and apparatus for depositing tungsten are provided herein. One aspect includes: (a) exposing a substrate in a chamber to alternating pulses of a reducing agent and a tungsten-containing precursor to deposit a tungsten nucleation layer on the substrate; And (b) exposing the substrate to alternating pulses of hydrogen and a tungsten-containing precursor to deposit a bulk tungsten layer over the tungsten nucleation layer, wherein during step (a) The chamber pressure is 10 Torr or less.

The method may further comprise: (c) exposing the substrate to a reducing agent and a tungsten-containing precursor simultaneously to deposit a second bulk tungsten layer. The method may further comprise (d) performing step (c) for every two or more cycles of step (b), wherein the cycle of step (b) comprises a pulse of hydrogen and a pulse of tungsten- do.

In various embodiments, step (b) is performed with cycles comprising a pulse of hydrogen and a pulse of tungsten-containing precursor, and each cycle forms a submonolayer having a thickness of at least about 0.3 A .

The tungsten-containing precursor of step (a) may be different from the tungsten-containing precursor of step (b). In some embodiments, the tungsten-containing precursor of step (a) is fluorine-free.

The deposited tungsten may have a tensile stress of less than about 1 micron per deposited 500 angstroms.

Another aspect provides a method of forming a tungsten layer, comprising: (a) exposing a substrate to a reducing agent; and (ii) exposing the substrate to a fluorine free tungsten-containing precursor; And (i) exposing the substrate to the hydrogen (H _2), (ii) the substrate second tungsten-exposing the containing precursor, and (iii) into one or more cycles to deposit the bulk tungsten layer (i ) And (ii), comprising depositing a bulk tungsten layer as a cycle, comprising depositing tungsten on the substrate.

In some embodiments, the fluorine-free tungsten-containing precursor is selected from the group consisting of metal-organic tungsten-containing precursors, tungsten chlorides, and tungsten hexacarbonyl.

In various embodiments, the fluorine free tungsten-containing precursor is tungsten hexachloride. In various embodiments, the fluorine free tungsten-containing precursor is tungsten pentachloride.

The tungsten layer of step (a) may be deposited to a thickness of about 2 A to about 100 A. [ Each of the cycles of step (b) may form a sub-mono layer having a thickness of at least about 0.3 Angstroms.

Another aspect includes a method comprising: (a) exposing a substrate to alternating pulses of hydrogen and a tungsten-containing precursor to deposit a bulk tungsten layer on the substrate; And (b) exposing the substrate to a tungsten-containing precursor and a reducing agent simultaneously to deposit a second bulk tungsten layer over the substrate.

In various embodiments, step (a) and step (b) are repeated sequentially.

The tungsten-containing precursor of step (b) may be a fluorine-free tungsten-containing precursor selected from the group consisting of metal-organic tungsten-containing precursors, tungsten chlorides, and tungsten hexacarbonyl.

In some embodiments, the tungsten-containing precursor of step (a) is different from the tungsten-containing precursor of step (b).

Yet another aspect includes a process chamber comprising: (a) at least one process chamber including a pedestal configured to hold a substrate; (b) at least one outlet for coupling with a vacuum; (c) one or more process gas inlets coupled to the one or more process gas sources; And (d) a controller for controlling operations within the apparatus, the controller comprising: (i) a processor for introducing a reducing agent and a tungsten-containing precursor into the process chamber in alternating pulses; Machine-readable instructions; And (ii) machine-readable instructions for introducing hydrogen and a tungsten-containing precursor into alternating pulses in the process chamber, wherein the chamber pressure during the machine-readable instruction (i) is less than or equal to 10 Torr.

Yet another aspect includes a process chamber comprising: (a) at least one process chamber including a pedestal configured to hold a substrate; (b) at least one outlet for coupling with a vacuum; (c) one or more process gas inlets coupled to the one or more process gas sources; And (d) a controller for controlling operations within the apparatus, the controller comprising: (i) a plasma processing system including (i) pulses of alternating hydrogen and tungsten in the process chamber to deposit a bulk tungsten layer Machine-readable instructions for introducing a precursor; And (ii) machine-readable instructions for concurrently introducing a tungsten-containing precursor and a reducing agent into the process chamber to deposit a second bulk tungsten layer. The controller may further include machine-readable instructions for serially repeating machine-readable instructions (i) and (ii).

These and other aspects are further described below with reference to the drawings.

Figure 1A is a schematic illustration of exemplary films on a substrate.
Figures 1B-1H are schematic illustrations of various structures in which tungsten may be deposited, according to the disclosed embodiments.
Figures 2a and 2b are process flow diagrams illustrating operations for methods in accordance with the disclosed embodiments.
2C is a timing sequence diagram illustrating exemplary cycles of a method, in accordance with the disclosed embodiments.
Figures 3A-J are schematic diagrams of examples of mechanisms for depositing films, in accordance with the disclosed embodiments.
3K is a process flow diagram illustrating operations for a method, in accordance with the disclosed embodiments.
4 is a schematic diagram of an exemplary process tool for performing the disclosed embodiments.
5 is a schematic diagram of an exemplary station for performing the disclosed embodiments.
6 shows various timing sequence diagrams.
Figures 7 to 11B are plots of experimental results.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments provided. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. The disclosed embodiments will be described in conjunction with specific embodiments, but it will be understood that they are not intended to limit the disclosed embodiments.

Tungsten (W) filling of features is often used in semiconductor device fabrication to form electrical contacts. As the devices scale to smaller technology nodes and more complex patterning structures are used, various challenges of tungsten filling occur. One task is to reduce the fluorine concentration or content in the deposited tungsten film. Compared to larger features, smaller features with smaller fluoride concentrations in the tungsten film have a greater impact on the performance of the device. For example, the smaller the feature, the thinner the films are deposited. As a result, fluorine in the deposited tungsten film adds diffusion through thinner films, potentially resulting in device failure.

One method of preventing fluorine diffusion involves depositing one or more barrier layers prior to depositing tungsten to prevent fluorine from diffusing from tungsten to other layers of the substrate, such as an oxide layer. For example, Figure IA shows an exemplary stack of layers deposited on a substrate. The substrate 190 may include a silicon layer 192, an oxide layer 194 (e.g., TiOx, TEOS, etc.), a barrier layer 196 (e.g., titanium nitride (TiN)), a tungsten nucleation layer (198), and a bulk tungsten layer (199). The barrier layer 196 is deposited to prevent fluorine diffusion from the bulk tungsten layer 199 and the tungsten nucleation layer 198 to the oxide layer. However, as the devices shrink, the barrier layers become thinner and fluorine may still diffuse out of the deposited tungsten layers. Although chemical vapor deposition (CVD) of bulk tungsten performed at higher temperatures produces lower fluorine content, these films have poor step coverage.

Another challenge is to reduce the resistance in the deposited tungsten films. Thinner films tend to have higher resistance than thicker films. As the features become smaller, the tungsten contact or line resistance increases due to the scattering effects of thinner tungsten films. Low resistivity tungsten films minimize power losses and overheating of integrated circuit designs. The tungsten nucleation layers typically have higher electrical resistivities than the top bulk layers. The barrier layers deposited in the contacts, vias, and other features may also have high resistivities. In addition, thin barrier and tungsten nucleation films occupy a larger percentage of smaller features and increase overall resistance in the features. The resistivity of the tungsten film depends on the thickness of the deposited film, and this resistivity increases as the thickness decreases due to boundary effects.

Another challenge is to reduce the stress on the deposited films. Thinner tungsten films tend to have increased tensile stress. Conventional techniques for depositing bulk tungsten films by CVD have tensile stresses greater than 2.5 microns for the 200 Å film. High thermal tensile stress curl the substrate, which makes subsequent processing difficult. For example, subsequent processes may include chemical mechanical planarization (CMP), deposition of materials, and / or clamping the substrate to a substrate holder to perform processes in the chamber. However, these processes often require a flat substrate, and the curled substrate causes non-uniform processing or incapability of substrate processing. There are conventional methods for reducing the stresses in the films of other materials, such as annealing, but tungsten has no surface mobility that would cause the particles to move or change if once deposited due to the high melting point of tungsten.

Methods for depositing tungsten films with low fluorine concentration using sequential CVD processes are provided herein. The deposited films may also have low stress. The processes involve introducing hydrogen and tungsten-containing precursors such as tungsten hexafluoride into the cycles. The disclosed embodiments may be integrated with other tungsten deposition processes to deposit a low stress tungsten film having a substantially lower fluorine content than films deposited by conventional CVD. For example, sequential CVD processes may be integrated with low pressure nucleation layer deposition processes, fluorine pre tungsten layer deposition processes, and / or non-sequential CVD processes. The disclosed embodiments have a wide variety of applications. The methods may be used to deposit tungsten into features with high step coverage and may also be used to deposit tungsten into 3D NAND and vertical NAND structures, including structures with deep trenches.

Sequential CVD processes are distinguished from non-sequential CVD, pulsed CVD, atomic layer deposition (ALD), and nucleation layer deposition. Non-sequential CVD processes involve simultaneous exposure of the two reactants such that both reactants flow simultaneously during deposition. For example, bulk tungsten may be deposited by simultaneously exposing the substrate to hydrogen (H ₂ ) and tungsten hexafluoride (WF ₆ ) for a duration sufficient to fill the features. Hydrogen and WF ₆ react during exposure to deposit tungsten into the features. In pulsed CVD processes, while one reactant material is pulsed while the other reactant is flowing, the substrate is exposed to both reactants during deposition to deposit the material for each pulse. For example, the substrate may be exposed to a continuous flow of H ₂ while WF ₆ is pulsed, and WF ₆ and H ₂ react during pulses to deposit tungsten.

In contrast, sequential CVD processes implement individual exposures for each of the reactants so that reactants do not flow into the chamber during deposition at the same time. Rather, each of the reactant flows is introduced into the chamber housing the substrate with the pulses temporally separated in sequence and repeated one or more times in cycles. Generally, the cycle is the minimum set of operations used to perform the surface deposition reaction once. The result of one cycle is the creation of at least one partial film layer on the substrate surface. The cycles of sequential CVD are described in more detail below.

ALD and nucleation layer deposition also involves exposing the substrate to two reactants with the pulses temporally separated into cycles. For example, in an ALD cycle, the first reactant flows into the chamber, the chamber is purged, the second reactant flows into the chamber, and the chamber is purged again. These cycles are typically repeated to build the film thickness. In conventional ALD and nucleation layer deposition cycles, the first reactant flow forms the first "dose" of the self-limiting reaction. For example, the substrate may comprise a limited number of active sites, the first reactant being adsorbed on the active sites on the substrate and saturating the surface, and the second reactant being deposited in layers by layer lt; RTI ID = 0.0 > layer < / RTI > material.

However, in sequential CVD, the reactants do not necessarily need to be adsorbed onto the active sites on the substrate and, in some embodiments, the reactions may not be self-limiting. For example, the reactants used in sequential CVD may have low adsorption rates. In addition, the reactants on the surface of the substrate may not necessarily react with the second reactant when the second reactant is introduced. Rather, in some embodiments of sequential CVD, some of the reactants on the substrate are not reacted during the cycle and are not reacted until further cycles. Some reactants may not react due to stoichiometric properties, steric hindrance, or other effects.

The methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon wafer, for example, a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, which may be a material, such as a dielectric, a conductive or semiconductive material And wafers having one or more layers. The substrates may include features such as vias or contact holes that may feature one or more of narrow openings and / or re-entrant openings, constrictions in features, and high aspect ratios . The features may be formed in one or more of the layers described above. For example, the features may be formed at least partially within the dielectric layer. In some embodiments, the features may have an aspect ratio of at least about 2: 1, at least about 4: 1, at least about 6: 1, at least about 10: 1, or even higher. One example of a feature is a hole or via in a layer on a semiconductor substrate or substrate.

Figures 1B-1H are schematic illustrations of various structures in which tungsten may be deposited, according to the disclosed embodiments. Figure IB shows an example of a cross-sectional view of a vertical feature 101 to be filled with tungsten. The features may include feature holes 105 in the substrate 103. The hole 105 may also have an opening diameter or line width that approximates the opening, for example, from about 10 nm to 500 nm, for example, from about 25 nm to 300 nm. The feature hole 105 may be referred to as an unfilled feature or simply as a feature. The features 101, and any features, may be used to partially (or at least partially) define an axis 118 that extends through the length of the feature, with horizontally-oriented features having vertically-oriented features and horizontal axes with vertical axes It can also be a feature.

In some embodiments, the features are trenches within the 3D NAND structure. For example, the substrate may comprise a word line structure with at least 60 lines, 18 to 48 layers, trenches at least 200 angstroms deep. Another example is a trench in a substrate or layer. The features may be features of any depth. In various embodiments, the features may have an under-layer such as a barrier layer or an adhesion layer. Non-limiting examples of sublayers include dielectric layers and conductive layers, such as silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers.

Fig. 1C shows an example of a feature 101 having a recessed profile again. The reentrant profile is a profile that narrows from the closed lower end to the feature opening or from the interior of the feature to the feature opening. According to various implementations, the profile may become narrower and / or may include overhang at the feature aperture. FIG. 1C illustrates the latter example with a lower layer 113 lining the inner surfaces or sidewalls of the feature hole 105. The lower layer 113 may be, for example, a diffusion barrier layer, an adhesive layer, a nucleation layer, a combination thereof, or any other suitable material. Non-limiting examples of sublayers may include dielectric layers and conductive layers, such as silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers. have. In certain embodiments, the underlayer can be one or more of Ti, TiN, WN, TiAl, and W. The lower layer 113 forms the overhang 115 such that the lower layer 113 is thicker than the inside of the feature 101 in the vicinity of the opening of the feature 101. [

In some implementations, the features may be filled with features having one or more constriction in the feature. Figure ID shows examples of drawings of various filled features with constriction. In Figures 1 (d), each of Figures (a), (b) and (c) includes a constriction 109 at an intermediate point in the feature. The constriction 109 may be, for example, about 15 nm to 20 nm wide. The constrictions may cause pinch off during depositing tungsten in the feature using conventional techniques, with deposited tungsten blocking the further deposition past the constriction before the portion of the feature is filled, Voids are generated. Example (b) further includes a liner / barrier overhang 115 in the feature opening. This overhang may also be a potential pinch-off point. The example (c) includes the constriction 112 further away from the field zone than the overhang 115 of example (b).

Horizontal features, such as 3-D memory structures, can also be filled. FIG. 1E shows an example of a horizontal feature 150 including a constriction 151. FIG. For example, the horizontal feature 150 may be a word line in the VNAND structure.

In some embodiments, the constriction may be due to the presence of pillars in the VNAND structure or other structures. 1F shows a top view of pillars 125 in a VNAND or vertically integrated memory (VIM) structure 148, and FIG. 1G shows a simplified schematic view of a cross-section of pillars 125. FIG. The arrows in Fig. 1f represent the deposition material; Because the pillars 125 are disposed between the region 127 and the gas inlet or other deposition source, adjacent pillars can generate stalks 151 that exhibit challenges in void-free filling of the region 127.

The structure 148 may be formed, for example, by depositing a stack of alternating interlayer dielectric layers 154 and sacrificial layers (not shown) on the substrate 100 and selectively etching the sacrificial layers. The interlayer dielectric layers may be silicon oxide and / or silicon nitride layers, for example, with sacrificial layers of selectively etchable material using an etchant. An etching process and a deposition process may be followed to form the pillars 125, which may include channel regions of the completed memory device.

The major surface of the substrate 100 may extend in the x and y directions and the pillars 125 are oriented in the z direction. In the example of Figures 1F and Ig, the pillars 125 are arranged in an offset manner so that adjacent pillars 125 immediately in the x-direction are offset from each other in the y-direction (and vice versa). According to various implementations, the pillars (and corresponding constrictions formed by adjacent pillars) may be arranged in any number of ways. In addition, the pillars 125 may be of any shape, including circular, square, and the like. Pillars 125 may comprise an annular semiconductive material, or a circular (or square) semiconductive material. The gate dielectric may surround the semiconductive material. The area between each of the interlayer dielectric layers 129 can be filled with tungsten; The structure 148 has a plurality of stacked horizontally-oriented features extending to fill in the x and / or y directions.

1 H provides another example of a view of a VNAND or other structure that includes a horizontal feature, e.g., pillar narrowing portions 151. The example of Figure 1h is open-ended so that the material to be deposited can enter horizontally from the two sides as indicated by the arrows. (Note that the example of FIG. 1h can be seen as 2-D features providing 3-D features of the structure, FIG. 1h is a cross-sectional view of the area to be filled and the pillars are shown with planes rather than cross- In some implementations, the 3-D structures may extend along two or three dimensions (e.g., in the x and y directions or in the x, y, and z directions in the example of Figure 1g) Can characterize the area to be filled and can provide more challenges for filling than filling holes or trenches that extend along one or two dimensions. For example, controlling the filling of 3-D structures can be difficult because the deposition gases may enter the features from multiple dimensions.

Examples of feature filling for horizontally-oriented features and vertically-oriented features are described below. It should be noted that, in most cases, these examples are applicable to both horizontally-oriented and vertically-oriented features. In addition, in the following description, the term "side" may be used to refer to a direction generally perpendicular to the feature axis, and the term "vertical" may be used to refer generally to a direction along a feature axis.

Although the following techniques focus on tungsten feature fill, aspects of the present disclosure may also be implemented in filling features with other materials. For example, feature filling using one or more of the techniques described herein may be performed using other tungsten-containing materials (e.g., tungsten nitride (WN) and tungsten carbide (WC)), titanium-containing materials (E.g., titanium (Ti), titanium nitride (TiN), titanium silicide (TiSi), titanium carbide (TiC), and titanium alumite (TiAl)), tantalum- , And tantalum nitride (TaN)), and other materials including nickel-containing materials (e.g., nickel (Ni) and nickel silicide (NiSi). The disclosed methods and apparatus are not limited to filling a feature, but may be used to deposit tungsten on any suitable surface, including forming blanket films on flat surfaces.

Figure 2a provides a process flow diagram for a method performed in accordance with the disclosed embodiments. Operations 202-210 of FIG. 2A are performed to deposit a tungsten nucleation layer by ALD. In various embodiments described herein, operations 202-210 are performed at a lower pressure than operation 280. [ For example, operations 202-210 may be performed at a low pressure of less than about 10 Torr. In some instances, operations 202-210 are performed at a pressure of about 10 Torr, or a pressure of about 3 Torr. Performing operations 202-210 at a low pressure, without being bound to any particular theory, is advantageous in that the fluorine concentration in the deposited tungsten film due to the lower partial pressure of the fluorine-containing precursor in the chamber when the film is deposited such that less fluorine is incorporated into the film . ≪ / RTI > Examples of processes for depositing a tungsten nucleation layer at low pressure to achieve a low fluorine concentration in deposited tungsten are described in U.S. Patent Application Serial No. 14 / 723,275, filed May 27, 2015 (Attorney Docket LAMRP 183/3623 -1US).

At act 202, the substrate is exposed to a tungsten-containing precursor such as WF ₆ . It is to be understood that for purposes of the present description WF ₆ is used as an example of a tungsten-containing precursor, other tungsten-containing precursors may be suitable for carrying out the disclosed embodiments. For example, metal-organic tungsten-containing precursors may be used. Organic-metal precursors and fluorine-free precursors such as MDNOW (methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW (ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten) may also be used. The tungsten-containing precursor may comprise a combination of these compounds. In some embodiments, a carrier gas, such as nitrogen (N ₂ ), argon (Ar), helium (He), or other inert gases may flow during operation 202.

Operation 202 may be performed for any suitable duration and at any suitable temperature. In some instances, operation 202 may be performed for a duration of from about 0.25 seconds to about 30 seconds, from about 0.25 seconds to about 5 seconds, or from about 0.5 seconds to about 3 seconds. In some embodiments, this operation may be performed for a duration sufficient to saturate active sites on the surface of the substrate.

In operation 204, the chamber is selectively purged to remove excess WF ₆ that is not adsorbed to the surface of the substrate. Reducing the pressure of the chamber by flowing an inert gas at a pumping fixed pressure and re-pressurizing the chamber before initiating another gas exposure.

At operation 206, the substrate is exposed to a reducing agent to deposit a tungsten nucleation layer. The reducing agent may be borane, silane, or germane. Exemplary boranes include borane (BH ₃ ), diborane (B ₂ H ₆ ), triboran, alkyl borane, amino borane, carboborane, and haloborane. Exemplary silanes include silane (SiH _4), disilane (Si ₂ H _6), trisilane s (Si ₃ H _8), of the alkyl silanes, amino silanes, carboxylic bosilran, and halosilane. Germans include Ge _n H _{n + 4} , Ge _n H _{n +6} , Ge _n H _{n +8} , and Ge _n H _m where n is an integer from 1 to 10 and n is an integer different from m . Other germans, for example, alkyl germans, amino germans, carbogermans, and halo germans may also be used. Generally, halo germans may not have significant reducing potential, but there may be tungsten-containing precursors and process conditions suitable for film formation using halo germans.

Operation 206 may be performed for any suitable duration. In some instances, exemplary durations include from about 0.25 seconds to about 30 seconds, from about 0.25 seconds to about 5 seconds, or from about 0.5 seconds to about 3 seconds. In some embodiments, this operation may be sufficient to react with the adsorbed layer of WF ₆ on the surface of the substrate. Operation 206 may be performed for a duration other than these exemplary ranges. In some embodiments, a carrier gas such as, for example, argon (Ar), helium (He), or nitrogen (N ₂ ) may be used.

After operation 208, there may be a selectable purge step to still purge the excess reducing agent that has not reacted with WF ₆ on the surface of the features in the gas phase. May be effected by flowing an inert gas through the purging fixed pressure, thereby reducing the pressure in the chamber and re-pressurizing the chamber before initiating another gas exposure.

At operation 210, it is determined whether the tungsten nucleation layer has been deposited to a sufficient thickness. If not, the operations 202-208 are repeated until the desired thickness of the tungsten nucleation layer is deposited on the surface of the feature. Each iteration of operations 202-208 may be referred to as an ALD "cycle ". In some embodiments, the order of operations 202 and 206 may be reversed if a reducing agent is introduced first.

After the tungsten nucleation layer is deposited to a sufficient thickness, at operation 280, bulk tungsten is deposited by sequential CVD. In various embodiments, operation 280 may be performed at a higher pressure than that during operations 202-210. For example, operation 280 may be performed at a pressure of at least about 10 Torr, e.g., about 10 Torr, or about 40 Torr.

FIG. 2B provides a process flow diagram for operations that may be performed during operation 280. FIG. The operations of FIG. 2B may be performed without performing the operations of FIG. 2A. FIG. 2C provides a timing sequence diagram illustrating exemplary cycles of sequential CVD of process 200. FIG. Figures 3A-3J are schematic illustrations of exemplary mechanisms for sequential CVD cycles.

In FIG. 2B, at operation 282, the substrate is exposed to a reducing agent such as H ₂ . This operation may be referred to as "pulse" or "dose ", which may be used interchangeably herein. In the embodiments described herein, although H ₂ is provided as an exemplary reducing agent, other reducing agents may be used including silanes, boranes, germanes, foams, hydrogen-containing gases, and combinations thereof Will be understood. Unlike the non-sequential CVD, H ₂ is pulsed without spilling another reactant. In some embodiments, a carrier gas may flow. The carrier gas may be any of those described above for operation 204 of FIG. 2A. Operation 282 may be performed for any suitable duration. In some instances, exemplary durations include from about 0.25 seconds to about 30 seconds, from about 0.25 seconds to about 5 seconds, or from about 0.5 seconds to about 3 seconds.

Figure 2C shows the H ₂ dose 220A of the deposition cycle 211A, which may correspond to operation 282 of Figure 2B. H ₂ During dose 220A, the carrier gas flows, the reducing agent is pulsed, and the WF ₆ flow is turned off.

3A illustrates an exemplary mechanism in which H ₂ is introduced into a substrate 300 having a tungsten nucleation layer 301 deposited thereon. Hydrogen is introduced into the gas phases 311a and 311b and some H ₂ 313a and 313b are on the surface of the tungsten nucleation layer 301 but may not need to be adsorbed on the surface. For example, H _2, but may not have to be chemically adsorbed onto the nucleation layer 301, and in some embodiments, may be physically adsorbed on the surface of the nucleation layer 301.

Referring back to FIG. 2B, at operation 284, the chamber is purged. This purge operation may also remove excess H ₂ remaining in the gas phase. Reducing the pressure of the chamber by flowing an inert gas through the purging fixed pressure and repressurizing the chamber before initiating another gas exposure. The chamber may be purged for any suitable duration, e. G., A duration of from about 0.1 seconds to about 3 seconds. Operation 284 of FIG. 2B may correspond to purge phase 240A of FIG. 2C. As shown in FIG. 2C, during the purge phase 240A, the carrier gas flows but the H ₂ flow and the WF ₆ flow are turned off. 3B shows an example in which the gas phase H ₂ (311 a and 311 b in FIG. 3 a) has been purged from the chamber and H ₂ (313 a and 313 b) on the surface has previously remained on the surface of the tungsten nucleation layer 301 ≪ / RTI >

Referring again to FIG. 2B, at operation 286, the substrate is exposed to a tungsten-containing precursor (e.g., WF ₆ ) to form a sub-monolayer of film on the substrate. In various embodiments, WF ₆ flows into the chamber during this operation for a duration of about 0.1 seconds to about 3 seconds, or about 0.5 seconds. In some embodiments, WF ₆ may be redirected to fill the gas line and change the line before dosing. In some embodiments, WF ₆ flows into the chamber but does not fully react with all the H ₂ molecules on the surface of the substrate. Act 286 may correspond to WF ₆ Dose 260A in Figure 2C. As shown in FIG. 2C, during the WF ₆ dose 260A, the carrier gas flows, the H ₂ flow is turned off, and the WF ₆ flow is turned on.

FIG. 3C shows an exemplary schematic for operation 286 of FIG. 2B. In Figure 3c, the substrate is part of, and WF ₆ exposed to WF ₆ is onto the gas, and (331a and 331b), a part of the WF ₆ is in the vicinity of the surface or the surface of the substrate (323a and 323b).

During operation 286 of FIG. 2B, some WF ₆ may react with H ₂ remaining on the surface from the previous dose. As shown in Figure 3D, WF ₆ may react with H ₂ to form intermediate product 343b temporarily, and intermediate product 343b in Figure 3e reacts with H ₂ to form substrate 300 on nucleation layer 301, (E. G., 351a and 351b), which is a gas phase.

During operation 286 of FIG. 2B, some WF ₆ may not fully react with the remaining H ₂ on the surface from the previous dose. 3D, WF ₆ may partially react with H ₂ to form intermediate product 343a, and in FIG. 3e, intermediate product 343a may be partially reacted with H ₂ to form substrate 300 on nucleation layer 301, Lt; / RTI > The reaction mechanism involving WF ₆ and H ₂ may be slower than the reaction between borane or silane or germane and WF ₆ for the deposition of a tungsten nucleation layer due to activation energy barriers and steric effects have. For example, without being tied to a particular theory, the stoichiometry of the WF ₆ can be used at least three H ₂ molecules to react with the WF ₆ molecule. It is possible that WF ₆ partially reacts with the molecules of H ₂ and forms an intermediate rather than forming tungsten. For example, this may occur if H ₂ is not sufficient near the stoichiometric principles (for example, three H ₂ molecules are used to react with one molecule of WF ₆ ) to react with WF ₆ Thereby leaving an intermediate product 343a on the surface of the substrate.

During operation 286 of FIG. 2B, in the absence of H ₂ that is physically adsorbed or remaining on the substrate surface, some WF ₆ may not react with H ₂ at all or may physically adsorb onto the surface of the substrate instead. In some embodiments, WF ₆ may remain on the substrate surface, but may not be physically adsorbed or chemisorbed to the surface.

In many embodiments, operation 286 of FIG. 2B may form a sub-mono layer of tungsten. For example, a sub-mono layer having a thickness of about 0.3 A may be deposited after performing operations 282 through 286.

In operation 288 of FIG. 2B, the chamber is purged to remove WF _6, which is the gas phase and the reacted by-products from the chamber. In some embodiments, the very short purge duration of operation 288 may increase non-sequential CVD reaction characteristics such that a higher stress film is deposited. In some embodiments, the purge duration is about 0.1 second to about 2 seconds, and may be due to the low absorption rate of WF ₆ to the surface of the tungsten to prevent the removal of all WF ₆ from the substrate surface. In some embodiments, the purge duration is from about 0.1 second to about 15 seconds, for example, about 7 seconds. For example, for the fabrication of a 3D NAND structure, the chamber may be purged for approximately 7 seconds during operation 288. The purge duration is determined by the substrate and stress.

Operation 288 of FIG. 2B may correspond to purge phase 270A of FIG. 2C. As shown in FIG. 2C, the purge phase 270A terminates the deposition cycle 211A. Figure 3f provides an exemplary schematic view of a substrate when the chamber is purged. Note that compound 343c may be an intermediate that is formed but not completely reacted, while some tungsten 390 may be formed on a substrate. Whereby each cycle forms a sub-mono layer of tungsten on the substrate.

In some embodiments, operation 286 and operation 282 may be reversed if operation 286 is performed before operation 282. [ In some embodiments, operation 282 may be performed before operation 286. [

At operation 290 of FIG. 2B, it is determined whether bulk tungsten has been deposited to a sufficient thickness. If not, then operations 282 through 288 are repeated until the desired thickness is deposited. In some embodiments, operations 282 through 288 are repeated until the feature is filled. In FIG. 2C, it is determined that bulk tungsten has not been deposited to a sufficient thickness, and operations 282 through 288 of FIG. 2B are then repeated with a deposition cycle 211B such that H ₂ dose 220B is performed and followed by a purge phase 240B. WF ₆ dose 260B is performed, followed by another purge phase 270B.

By way of example, Figure 3g illustrates the operation 282, wherein gaseous H ₂ (311c) of a repeat cycle is introduced into the substrate with a tungsten (390) and in part of the intermediate product reaction (343d) deposited on top. The introduced H ₂ is now heated on the substrate such that the reacted compound 343 d leaves the deposited tungsten 390 b and 390 c and the byproducts HF 351 c and 351 d are formed in the gas phase, Note that it may react completely with the intermediate product 343d. Some H ₂ 311c may remain in the gas phase while some H ₂ 313c may remain on the tungsten layer 390a. In FIG. 3i, the chamber is purged (corresponding to operation 284 in FIG. 2B, or operation 240B in FIG. 2C), leaving deposited tungsten 390a, 390b, and 390c, and some H ₂ 313c. In Figure 3j, WF ₆ is introduced back into the dose so that also the molecules (331c and 323c) is sucked and H ₂ and the substrate and / or H ₂ and the substrate and reaction. 3J may correspond to operation 286 of FIG. 2B or 260B of FIG. 2C. After the WF ₆ dose, the chamber may be purged again and the cycles may be repeated again until the desired thickness of tungsten is deposited.

The tungsten films deposited using the disclosed embodiments have low fluorine concentrations, such as a fluorine concentration that is about two orders of magnitude smaller than tungsten deposited by non-sequential CVD. Deposition conditions, such as temperature, pulse times, and other parameters, may vary depending on hardware or process modifications. The total tensile stress of the membranes may be less than about 1 micron.

3K provides a process flow diagram for a method performed in accordance with the disclosed embodiments. At act 280, bulk tungsten is deposited by sequential CVD. The process conditions and chemical reactions may be any of those described above with respect to Figure 2b and Figures 3a-3j. At act 299, bulk tungsten is deposited by non-sequential CVD. During non-sequential CVD, the substrate is exposed to the tungsten-containing precursor and the reducing agent to simultaneously deposit bulk tungsten. Include those containing precursor (e.g., WCl _x), and tungsten hexa-carbonyl (W (CO) ₆₎ - s-containing precursor (e.g., WF _6), chlorine-illustrative tungsten-containing precursor are fluorine . Exemplary reducing agents include hydrogen. In some embodiments, non-sequential CVD is deposited by exposing the substrate to WF ₆ and H ₂ . Operations 280 and 299 may be performed sequentially, or any operation 280 may be performed one or more times before or after performing operation 299. In some embodiments, operations 280 and 299 are performed with pulses such that operation 299 is performed every two or more cycles to perform operation 280. Thus, bulk tungsten may be deposited using a combination of sequential and non-sequential CVD.

The disclosed embodiments may have a variety of applications in tungsten deposition processes. For example, in some embodiments, the features may be filled by depositing a tungsten nucleation layer by ALD cycles of alternating pulses of a reducing agent (e.g., borane, silane, or germane) and WF ₆ , Followed by bulk tungsten deposition by sequential CVD as described above for FIG. 2B.

In another example, in some embodiments, the tungsten nucleation layer may be deposited using ALD cycles of WF _{6 with} a reducing agent, and the reducing agent and fluorine free tungsten-containing precursor (as described above for FIG. 2B) Followed by bulk tungsten deposition using a combination of CVD and sequential CVD of fluorine-free tungsten using, for example, a metal-organic tungsten precursor. The fluorine-free tungsten precursors may also include tungsten carbonyls (W (CO) ₆ ), and tungsten chlorides (WCl _x ) such as tungsten pentachloride (WCl ₅ ) and tungsten hexachloride (WCl ₆ ).

In another example, a tungsten nucleation layer may be deposited on the feature by ALD cycles of alternating pulses of WF _{6 with} a reducing agent, and bulk tungsten may be deposited by sequential CVD as described above for FIG. 2B May be deposited by alternating between non-sequential CVD. For example, bulk tungsten may be deposited using a plurality of cycles of sequential CVD between predetermined durations of non-sequential CVD. In a particular example, bulk tungsten may be deposited using about 5 cycles of sequential CVD, followed by 5 seconds of non-sequential CVD, then 5 cycles of sequential CVD, and another 5 seconds of nonsequential CVD.

In another example, the feature may first be filled by depositing a tungsten nucleation layer by ALD cycles of alternating pulses of a reducing agent and WF ₆ , then partially filling the feature using sequential CVD, The rest of the features are filled by sequential CVD.

In another example, the features may be filled by depositing a tungsten nucleation layer by ALD cycles of alternating pulses of WF _{6 with} a reducing agent, followed by partial deposition of bulk tungsten by sequential CVD, Followed by complete bulk filling by CVD of tungsten (like using a metal-organic tungsten precursor). For example, a plurality of cycles of sequential CVD they may be performed to partially filling the feature with bulk tungsten, followed by CVD with simultaneous exposure of about MDNOW and H ₂ so as to fill the remainder of the object. Note that in some embodiments, the feature may be filled without depositing the nucleation layer, but the nucleation layer may help to reduce the growth retardation of the bulk tungsten.

It will be appreciated that various combinations of applications described herein may be used to deposit tungsten and that the methods are not limited to the examples provided herein. For example, tungsten pentachloride (WCl ₅₎ with tungsten hexa chloride (WCl ₆₎ and such chlorine-containing tungsten precursors (WCl _x) is the embodiment of WF ₆ in place of or in WF ₆ in combination with the technology herein .

In various embodiments, a soak or surface treatment operation may be performed prior to depositing the nucleation layer. An exemplary soak or surface treatment are a silane to the substrate (SiH _4), disilane (Si ₂ H _6), trisilane (Si ₃ H _8), germane (GeH _4), argon (Ar), tungsten hexafluoride (WF ₆ ), diborane (B ₂ H ₆ ), hydrogen (H ₂ ), nitrogen (N ₂ ) gas, or combinations thereof. In some embodiments, the substrate may be soaked using one or more gases. For example, in some embodiments, the substrate may be exposed to silane for a first duration and then to diborane for a second duration. These operations may also be repeated in cycles. In another example, the substrate may be exposed to diborane for a first duration and then to a silane for a second duration. In another example, the substrate may be exposed to diborane for a first duration and then to hydrogen for a second duration. In another example, the substrate may be exposed to silane for a first duration and then to hydrogen for a second duration. In some embodiments, the substrate may be exposed to nitrogen gas in combination with any of the soaking processes described above. In any of the disclosed embodiments, the chamber housing the substrate may be purged between one or more soak operations. Or may be performed by flowing an inert gas such as argon into the chamber. For example, in one example, the substrate may be exposed to diborane for a first duration, then the chamber may be purged, and then the substrate may be exposed to the silane for a second duration.

Certain disclosed embodiments of the nucleation layer deposited according to prior to the deposition of the bulk tungsten layers include tungsten-containing containing precursor and a reducing agent, such as silane (SiH _4), disilane (Si ₂ H _6), trisilane (Si ₃ H ₈ ), germane (GeH ₄ ), or diborane (B ₂ H ₆ ). In some embodiments, the nucleation layer is deposited by exposing the substrate to alternating pulses of tungsten-containing precursor and silane. In some embodiments, the nucleation layer is deposited by exposing the substrate to alternating pulses of tungsten-containing precursor and diborane. In some embodiments, the nucleation layer is deposited by exposing the substrate to alternating pulses of tungsten-containing precursor and silane, followed by exposing the substrate to alternating pulses of tungsten-containing precursor and diborane. In some embodiments, the nucleation layer is deposited by exposing the substrate to alternating pulses of tungsten-containing precursor and diborane, followed by exposing the substrate to alternating pulses of tungsten-containing precursor and silane. In some embodiments, the nucleation layer is formed by exposing the substrate to alternating pulses of tungsten-containing precursor and silane, followed by exposing the substrate to alternating pulses of tungsten-containing precursor and diborane, followed by tungsten-containing And is then deposited by exposing the substrate to alternating pulses of the precursor and silane. In some embodiments, the nucleation layer is formed by exposing the substrate to alternating pulses of tungsten-containing precursor and diborane, followed by exposing the substrate to alternating pulses of tungsten-containing precursor and silane, followed by a tungsten-containing And is then deposited by exposing the substrate to alternating pulses of the precursor and diborane. In any of the disclosed embodiments, the chamber housing the substrate may be purged between one or more dose operations to deposit the nucleation layer. Or may be carried out by flowing an inert gas such as argon into the purging chamber. Any suitable inert gas may be used for purge. For example, in some embodiments, the substrate may be exposed to pulses of a tungsten-containing precursor, and then the chamber may be purged, and then the substrate may be exposed to pulses of silane and the chamber may be purged again And these operations may be repeated in cycles.

Nucleation layer deposition, which may be used in any of the above-described embodiments, may be performed during the entire nucleation deposition process, or during silane dosing, or during diborandone, or during tungsten-containing precursor doses such as WF ₆ dose, Flowing co-flow of any one of hydrogen (H ₂ ), argon (Ar), nitrogen (N ₂ ), or combinations thereof during the purge times of the purge gas. In some embodiments, the surface treatment operation is performed by exposing the substrate to any of silane, disilane, trisilane, germane, diborane, hydrogen, tungsten hexafluoride, nitrogen, argon, ≪ / RTI > or after nucleation growth. For example, during the deposition of the nucleation layer, the substrate may be exposed to a silane and an alternating pulse of WF _6, and then the substrate may be exposed to a silane soak, and then the substrate is alternating pulses of silane and WF ₆ Lt; / RTI > These operations may be performed in cycles. For example, in some embodiments, the following cycle may be repeated one or more times to deposit the nucleation layer: alternating pulses of SiH ₄ and WF ₆ and exposure treatment to the surface.

In some embodiments, the nucleation layer may be deposited by exposing the substrate to any combination of any one or more of the following gases with a tungsten-containing precursor in any sequence and order: diborane, silane, disilane , triethoxy silane, hydrogen, nitrogen, and germane (GeH _4). For example, in some embodiments, the nucleation layer may be deposited by exposing the substrate to diborane, exposing the substrate to tungsten hexafluoride, exposing the substrate to silane, and exposing the substrate to hydrogen . These operations may be repeated in one or more cycles. In another example, in some embodiments, the nucleation layer may be deposited by exposing the substrate to silane, by exposing the substrate to tungsten hexafluoride, and by exposing the substrate to hydrogen. These operations may be repeated in one or more cycles. In another example, in some embodiments, the nucleation layer may be deposited by exposing the substrate to diborane, exposing the substrate to hydrogen, and exposing the substrate to tungsten hexafluoride. These operations may be repeated in one or more cycles. In another example, in some embodiments, the nucleation layer may be deposited by exposing the substrate to nitrogen, by exposing the substrate to diborane, and by exposing the substrate to tungsten hexafluoride. These operations may be repeated in one or more cycles. In another example, in some embodiments, the nucleation layer may be deposited by exposing the substrate to silane, exposing the substrate to nitrogen, and exposing the substrate to tungsten hexafluoride. These operations may be repeated in one or more cycles. In any of the described embodiments, the substrate may be exposed to surface treatment operations and / or sorching operations before, during, or after deposition of the nucleation cycle using any available gas. In some embodiments, additional gases may flow with any of the above-described gases during one or more exposures of the nucleation deposition process. In any of the disclosed embodiments, the chamber housing the substrate may be purged between one or more dose operations to deposit the nucleation layer. Or may be carried out by flowing an inert gas such as argon into the purging chamber. Any suitable inert gas may be used for purging.

Bulk tungsten is disclosed in U.S. Patent Application Serial No. 14 / 723,275, filed May 27, 2015, the disclosure of which is incorporated herein by reference in its entirety, all of the disclosed embodiments described in this specification, and the Attorney Docket LAMRP183 / 3623- 1US). ≪ / RTI > In all of the above-described embodiments, bulk tungsten may also be periodically deposited with conventional CVD deposition operations performed between nucleation and / or soaking and / or surface treatment and / or bulk deposition. For example, in some embodiments, bulk tungsten may be deposited using the disclosed embodiments, as described above for FIG. 2B, and then bulk tungsten deposition may be discontinued, It may be exposed to the silane and WF _6, or the diborane and the alternating pulse of WF ₆ to generate, and then the bulk tungsten deposition may be resumed by using the disclosed embodiments, as described above with respect to Figure 2b. These operations may be repeated in any number of cycles. In another example, in some embodiments, bulk tungsten may be deposited using the disclosed embodiments, as described above for FIG. 2B, and then the bulk tungsten deposition may be stopped, May be exposed to soaking or surface treatment by flowing any of silane, disilane, trisilane, germane, diborane, hydrogen, tungsten hexafluoride, nitrogen, argon, and combinations thereof, The tungsten deposition may be resumed using the disclosed embodiments as described above with respect to FIG. 2B. Bulk tungsten deposition may be performed by exposing the substrate to any one or more of the following gases with a tungsten-containing precursor such as WF ₆ : hydrogen, silane, disilane, trisilane, diborane, nitrogen, argon, and The Germans. Bulk tungsten may also be deposited using a combination of conventional CVD and sequential CVD as described above with respect to Figure 3k. Conventional CVD may be performed before, during, or after deposition of bulk tungsten (such as by circulating between sequential CVD and conventional CVD) using sequential CVD.

In some embodiments, the substrate may be annealed at any suitable temperature prior to depositing the bulk tungsten and after depositing the nucleation layer. In some embodiments, the substrate may be annealed at any suitable temperature after depositing the bulk tungsten layer. In some embodiments, the substrate may be annealed at any suitable temperature during intermediate times during the deposition of bulk tungsten. The annealing may be performed in any suitable gaseous environment, such as an environment comprising one or more of the following gases: a tungsten-containing gas such as WF ₆ , hydrogen, silane, disilane, trisilane, diborane, nitrogen, argon, .

In various embodiments, the chamber housing the substrate may be pumped or purged before or after the doses of the tungsten-containing precursor and reducing agent to deposit bulk tungsten, as described above with respect to Figure 2B, in accordance with the disclosed embodiments. have. In some embodiments, the delay time may be included in a dose or purge step of sequential CVD deposition as described herein. In some embodiments, one or more gases may be removed during a dose or purge operation using one or more of the following gases: WF ₆ , hydrogen, silane, disilane, trisilane, diborane, nitrogen, argon, It may flow together.

The temperature of the substrate during nucleation deposition may not be the same as the temperature of the substrate during sequential CVD as described above for Figure 2B. The temperature of the substrate will be understood to mean the temperature at which the pedestal holding the substrate is set. The disclosed embodiments may be performed at any suitable pressure, for example, pressures of greater than about 10 Torr, or pressures of less than about 10 Torr. For multi-station chambers, each of the pedestals may be set to different temperatures. In some embodiments, each pedestal is set to the same temperature. The substrates may be cycled from station to station for some or all of any of the above-described operations in accordance with the disclosed embodiments. The chamber pressure may also be adjusted in one or more of the operations of certain disclosed embodiments. In some embodiments, the chamber pressure during nucleation deposition is different from the chamber pressure during bulk deposition. In some embodiments, the chamber pressure during nucleation deposition is equal to the chamber pressure during bulk deposition.

During any of the above-described exposures, the gases may be pulsed or flow continuously. For example, in some embodiments, during a WF ₆ dose of sequential CVD operation, WF ₆ may be pulsed more than once during a single dose. Likewise, in some embodiments, during purge, the inert gas may be pulsed during a single purge operation for more than one time. Such pulsing operations may be performed during any operation of nucleation deposition or any operation of bulk deposition or any combination thereof. In some embodiments, one or more changes to one or more parameters, such as pressure, flow rate, and temperature, may be used. In some embodiments, the pedestal may be moved during nucleation or bulk deposition, or any operation of both, such that the gap between the substrate and the showerhead over the pedestal may be adjusted. Moving the pedestal may be used in combination by changing one or more parameters such as pressure, temperature, or flow rate. Adjusting the gap between the substrate and the showerhead can affect the pressure, temperature, or flow rate, which may be used according to certain disclosed embodiments. It will be appreciated that any of the processes described herein may be applicable to techniques involving ALD.

Device

Any suitable chamber may be used to implement the disclosed embodiments. An exemplary deposition apparatus may include various systems, for example, CA available from Lam Research Corp. of Fremont ^® material available ALTUS and ALTUS Max ^®, or obtained by any of a variety of other commercially available processing system. In some embodiments, sequential CVD may be performed at a first station that is one of two, five, or even more deposition stations located in a single deposition chamber. Thus, for example, hydrogen (H ₂ ) and tungsten hexafluoride may be introduced alternately from the first station to the surface of the semiconductor substrate, using a separate gas supply system that creates a localized atmosphere on the substrate surface . Another station may be used for fluorine-free tungsten deposition, or for non-sequential CVD. Another station may be used to deposit the tungsten nucleation layer at low pressure. Two or more stations may be used to deposit tungsten in parallel processing. Alternatively, the wafer may be indexed to perform sequential CVD operations sequentially on two or more stations.

4 is a block diagram of a processing system suitable for conductive tungsten film deposition processes, in accordance with embodiments. The system 400 includes a transfer module 403. The transfer module 403 provides a clean, pressurized environment between the various reactor modules to minimize the risk of contamination of the substrates to be processed as the substrates to be processed are moved. A multi-station reactor 409 capable of performing ALD and sequential CVD is mounted on the transfer module 403 in accordance with embodiments. The multi-station reactor 409 may be used to perform fluorine-free tungsten deposition and / or non-sequential CVD in some embodiments. The multi-station reactor 409 may include a plurality of stations 411, 413, 415, and 417 that may perform operations sequentially in accordance with the disclosed embodiments. For example, a multi-station reactor 409 may be used to perform the nucleation layer deposition by ALD, the station 413 performing sequential ALD, and the station 415 performing fluorine-free tungsten deposition And the station 417 may be configured to perform non-sequential CVD. The stations may include a heated pedestal or substrate support, one or more gas inlets or a showerhead or a diffusion plate. An example of a deposition station 500 that includes a wafer support 502 and a showerhead 503 is shown in FIG. The heater may be provided in the pedestal portion 501.

One or more single or multi-station modules 407 capable of performing plasma or chemical (non-plasma) line-cleaning may also be mounted on the transfer module 403. The module may also be used to prepare the substrate for various processes, for example, a deposition process. System 400 also includes one or more wafer source modules 401 in which wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 419 may first remove wafers from the source modules 401 to the load locks 421. A wafer transfer device (generally a robotic arm unit) within the transfer module 403 moves wafers from the load locks 421 to modules mounted on the transfer module 403 and between the modules.

In various embodiments, the system controller 429 is employed to control process conditions during deposition. The system controller 429 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, and the like.

The system controller 429 may control all activities of the deposition apparatus. The system controller 429 may also include a set of instructions for controlling timing, mixing of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, Run the included system control software. Other computer programs stored on the memory devices associated with the controller 429 may be employed in some embodiments.

There will typically be a user interface associated with the controller 429. The user interface may include a display screen, a graphical software display of the device and / or a graphical software display of process conditions, and user input devices such as pointing devices, keyboards, touchscreens, microphones,

The system control logic may be configured in any suitable manner. Generally, the logic may be designed and configured in hardware and / or software. The instructions for controlling the drive circuitry may be hard-coded or provided as software. The instructions may be provided by "programming ". Such programming is understood to encompass any type of logic, including hard-coded logic, application-specific integrated circuits (ASICs) within the digital signal processors, and other devices with specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. The system control software may be coded in any suitable computer readable programming language.

The computer program code for controlling germanium-containing reductant pulses, hydrogen flow, and tungsten-containing precursor pulses, and other processes in the process sequence may be stored in any conventional computer readable programming language, C ++, Pascal, and Fortran. The compiled object code or script is executed by the processor to perform the tasks identified in the program. As also shown, the program code may be hard-coded.

The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe, and may be input using a user interface.

Signals for monitoring the process may also be provided by the analog input and / or digital input connections of the system controller 429. Signals for controlling the process are output on the analog output connection and the digital output connection of the deposition apparatus 400.

The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be created to control the operation of chamber components required to perform deposition processes in accordance with the disclosed embodiments. Examples of programs or program sections for this purpose include a substrate positioning code, a process gas control code, a pressure control code, and a heater control code.

In some implementations, the controller 429 is part of a system that may be part of the examples described above. Such systems may include semiconductor processing equipment, including processing tools or tools, chambers or chambers, processing platforms or platforms, and / or specific processing components (wafer pedestal, gas flow system, etc.) . These systems may be integrated into an electronic device for controlling their operation prior to, during, and after the processing of a semiconductor wafer or substrate. An electronic device may also be referred to as a "controller" that may control various components or sub-components of the system or systems. The controller 429 may control the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, and the like, depending on the processing requirements and / RF configuration settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, location and operation settings in some systems, May also be programmed to control any of the processes described herein, including wafer transfers into and out of load locks, interfacing with or interfacing with a particular system, tools, and other delivery tools.

Generally speaking, the controller may be implemented with various integrated circuits, logic, memory, and / or software that receive instructions and issue instructions, control operations, enable cleaning operations, enable endpoint measurements, May be defined as an electronic device. The integrated circuits may be implemented as chips that are in the form of firmware that stores program instructions, digital signal processors (DSPs), chips that are defined as application specific integrated circuits (ASICs), and / or one that executes program instructions (e.g., Microprocessors, or microcontrollers. The program instructions may be instructions that are passed to the controller or to the system in the form of various individual settings (or program files) that define operating parameters for executing a particular process on a semiconductor wafer or semiconductor wafer. In some embodiments, the operating parameters may be varied to achieve one or more processing steps during fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / It may be part of the recipe specified by the engineer.

The controller 429, in some implementations, may be coupled to or be part of a computer that is integrated into the system, coupled to the system, or otherwise networked to the system, or a combination thereof. For example, the controller 429 may be part or all of a factory host computer system capable of remote access to wafer processing, or may be in a "cloud ". The computer monitors the current progress of manufacturing operations, examines the history of past manufacturing operations, examines trends or performance metrics from a plurality of manufacturing operations, changes parameters of current processing, and performs processing steps following current processing Or may enable remote access to the system to start a new process. In some instances, a remote computer (e.g., a server) may provide process recipes to the system via a network that may include a local network or the Internet. The remote computer may include a user interface that enables input or programming of parameters and / or settings to be communicated from the remote computer to the system at a later time. In some instances, the controller receives instructions in the form of data, specifying parameters for each of the process steps to be performed during one or more operations. It should be appreciated that these parameters may be specific to the type of tool that is configured to control or interfere with the controller and the type of process to be performed. Thus, as described above, the controllers may be distributed, for example, by including one or more individual controllers networked together and cooperating together for common purposes, e.g., for the processes and controls described herein. An example of a distributed controller for this purpose is one or more integrated on a chamber communicating with one or more integrated circuits located remotely (e. G., At the platform level or as part of a remote computer) Circuits.

Exemplary systems include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a PVD chamber or module, a CVD A chamber or module, an ALD chamber or module, an ALE (atomic layer etch) chamber or module, an ion implantation chamber or module, a track chamber or module, and semiconductor wafers And may include any other semiconductor processing systems.

As described above, depending on the process steps or steps to be performed by the tool, the controller may be used to transfer the material to move the containers of wafers from / to the tool positions and / May communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located all over the plant, main computer, other controller or tools.

Controller 429 may include various programs. The substrate positioning program may include program code for controlling the chamber components used to load the substrate onto a pedestal or chuck and to control the space between the substrate and other portions of the chamber, such as the gas inlet and / or target . The process gas control program may include gas composition and flow rates, a code for controlling pulse times, and a code for channeling gas into the chamber prior to deposition to selectively stabilize the pressure in the chamber. The pressure control program may, for example, comprise a code for controlling the pressure in the chamber by adjusting the throttle valve of the exhaust system of the chamber. The heater control program may include a code for controlling the current to the heating unit used to heat the substrate. Alternatively, the heater control program may control the transfer of heat transfer gas, such as helium, to the wafer chuck.

Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as manometers, and thermocouples located within a pedestal or chuck. Properly programmed feedback and control algorithms may be used as data from these sensors to maintain the desired process conditions.

The foregoing describes an implementation of embodiments disclosed in a single or multi-chamber semiconductor processing tool. The apparatus and process described herein may be used with lithographic patterning tools or processes, for example, during manufacturing or fabrication of semiconductor devices, displays, LEDs, photoelectric panels, and the like. Typically, but not necessarily, such tools / processes will be used or implemented together in a common manufacturing facility. Lithographic patterning of the film generally involves the following steps: (1) use a spin-on tool or a spray-on tool, each of which is provided using a plurality of possible tools Applying a photoresist on the workpiece, i. E. The substrate; (2) curing the photoresist using a hot plate or a furnace or UV curing tool; (3) exposing the photoresist to visible or UV or x-ray light using a tool such as a wafer stepper; (4) developing the resist to pattern the resist by selectively removing the resist using a tool such as a wet bench; (5) transferring the resist pattern into a lower film or workpiece by using a dry or plasma assisted etching tool; And (6) removing the resist using a tool such as a RF or microwave plasma resist stripper.

Experiment

Experiment 1

The experiment was carried out on four processes for depositing bulk tungsten at 395 ° C and a pressure of 40 Torr. In each of the processes, bulk tungsten was deposited on the deposited tungsten nucleation layer using ALD alternating cycles of diborane (B ₂ H ₆ ) and tungsten hexafluoride (WF ₆ ). Figure 6 provides exemplary pulsing schemes for each of these four processes. In Process 1, H ₂ and WF ₆ flow simultaneously and continuously into the chamber, as during conventional CVD. In Process 2, H ₂ flows continuously while WF ₆ is pulsed (e.g., pulsed CVD). In Process 3, WF ₆ flows continuously while H ₂ is pulsed (e.g., pulsed CVD). In process 4, H ₂ and WF ₆ is the method described above with respect to Figure 2b is pulsed alternately by using the same method as in (for example, the subsequent CVD). The thickness, stress, non-uniformity, and resistivity of the tungsten nucleation layer of the deposited films using each of these four processes are measured and compiled in Table 1 below.

Resistivity and stress process Nucleation layer thickness
(A) Stress
(MPa) Non-uniformity
(%) Resistivity
(μohm-cm) One 507 2251 10.89 13.32 2 533 2207 4.31 12.79 3 517 2275 41.56 13.20 4 673 1634 21.77 10.81

As shown in Table 1, both the stress and the resistivity of the tungsten film deposited using Process 4 are considerably lower than those of the films deposited using any of the processes 1-3.

Experiment 2

Experiments were conducted on processes for depositing bulk tungsten on two substrates, both of which were deposited by ALD alternating cycles of a titanium nitride (TiN) barrier layer and B ₂ H ₆ and WF ₆ ≪ / RTI > tungsten nucleation layer. One substrate involved the deposition of bulk tungsten, using non-sequential CVD, which involved simultaneously exposing the substrate to WF ₆ and H ₂ at 300 ° C. Another substrate involved deposition of bulk tungsten, using sequential CVD as described above for FIG. 2B, followed by alternating pulses of WF ₆ and H ₂ at a chamber pressure of 10 Torr. The fluorine concentration was measured for both substrates. The conditions for this experiment are shown in Table 2. The results are plotted in FIG.

Experiment 2 Conditions 700
Non-sequential CVD 701
Sequential CVD Barrier  layer TiN TiN Nucleation  layer ALD
B ₂ H ₆ / WF ₆ ALD
B ₂ H ₆ / WF ₆
10 Torr bulk Tungsten layer CVD
WF ₆ and H ₂
300 ° C Sequential CVD
WF ₆ / H ₂
10 Torr

Line 700 represents the fluorine concentration for a substrate having tungsten deposited by non-sequential CVD. Line 701 shows the fluorine concentration for the substrate with tungsten deposited by sequential CVD. The W / TiN interface line at about 350 A represents the interface between the tungsten nucleation layer and the TiN barrier layer. The TiN / oxide interface, dashed at about 475 A, represents the interface between the TiN barrier layer and the oxide. The fluorine concentration on the y-axis of the plot is expressed in digits, and the sequential CVD fluorine concentration 701 is substantially lower than the non-sequential CVD fluorine concentration 700 - up to two orders of magnitude less fluorine concentration at some substrate depths.

Experiment 3

Experiments have been conducted on processes for depositing bulk tungsten on substrates at different pressures. Each of the three substrates included a TiN barrier layer. One substrate involved the deposition of a tungsten nucleation layer deposited by ALD alternating cycles of B ₂ H ₆ and WF ₆ at 10 Torr and the CVD of bulk tungsten by exposing the substrate to WF ₆ and H ₂ at 300 ° C . Another substrate involved the deposition of a tungsten nucleation layer deposited by ALD alternating cycles of B ₂ H ₆ and WF ₆ at 10 Torr and a bulk deposition by alternating pulses of WF ₆ and H ₂ at 10 Torr Subsequent CVD of tungsten is followed. The third substrate involved an ALD of the deposited tungsten nucleation layer by alternating the cycles of B ₂ H ₆ and WF ₆ at 3 Torr, and the alternating pulses of bulk tungsten, using alternating pulses of WF ₆ and H ₂ at 10 Torr Sequential CVD is followed. The fluorine concentration was measured for all three substrates. The conditions for this experiment are shown in Table 3. The results are plotted in FIG.

 Experiment 3 Conditions 800
Non-sequential CVD 801
Sequential CVD at high pressure
803
Sequential CVD at low pressure Barrier  layer TiN TiN TiN Nucleation  layer ALD
B ₂ H ₆ / WF ₆ ALD
B ₂ H ₆ / WF ₆
10 Torr ALD
B ₂ H ₆ / WF ₆
3 Torr bulk Tungsten layer CVD
WF ₆ and H ₂
300 ° C Sequential CVD
WF ₆ / H ₂
10 Torr Sequential CVD
WF ₆ / H ₂
10 Torr

Line 800 represents the fluorine concentration for the first substrate, in which bulk tungsten is deposited by non-sequential CVD. The dashed line 801 represents the fluorine concentration for the second substrate, in which the nucleation layer is deposited at 10 Torr followed by bulk tungsten deposition by sequential CVD. Dashed line 803 represents the fluorine concentration for the third substrate, where the nucleation layer is deposited at 3 Torr followed by bulk tungsten deposition by sequential CVD. The results show that the low pressure nucleation layer 803 following sequential CVD shows a lower fluorine concentration than the second substrate 801, even at the W / TiN interface and even in the TiN layer (350 A to 475 A) Show. This implies that the fluorine diffusion into the TiN layer and into the oxide may be reduced due to the reduced amount of fluorine concentration in the tungsten film.

Experiment 4

Experiments were conducted on processes for depositing bulk tungsten on substrates using different combinations of tungsten deposition. Three substrates were compared. One substrate is a 18 Å tungsten nucleation layer deposited at 3 Torr using ALD alternating with pulses of 1 Å of thermal oxide, 30 Å TiN, WF ₆ and B ₂ H ₆ , and a sequence of WF ₆ and H ₂ And bulk tungsten deposited at 10 Torr using CVD pulses. The fluorine concentration of this substrate is shown by the broken line 912 in Fig. Another substrate is a 12 Å tungsten nucleation layer deposited at 3 Torr using ALD alternating with pulses of 1 kA of thermal oxide, 30 Å TiN, 10 Å of fluorine-free tungsten, WF ₆ and B ₂ H ₆ , and And bulk tungsten deposited by sequential CVD at 10 Torr using pulses of WF ₆ and H ₂ . The fluorine concentration of this second substrate is shown by line 911 in Fig. The third substrate is a 12 Å tungsten nucleation layer deposited at 3 Torr using ALD alternating with pulses of 5 kA TEOS-deposited oxide, 30 Å fluorine-free tungsten, WF ₆ and B ₂ H ₆ , and WF ₆ and H ₂ at 10 Torr. ≪ tb >< TABLE > Columns = ₂ < tb > The fluorine concentration of this substrate is shown by the dotted line 913 in Fig. The layers as deposited on each substrate for this experiment are summarized in Table 4.

Experiment 4 Conditions 911 912 913 The first layer 1 kA thermal oxide 1 kA thermal oxide 5 kA TEOS-deposited oxide Second layer 30 Å TiN 30 Å TiN 30 Å fluorine-free tungsten Third Floor 10 A fluorine-free tungsten 18 Å ALD
Nucleation layer
B ₂ H ₆ / WF ₆
3 Torr 12 Å ALD
Nucleation layer
B ₂ H ₆ / WF ₆
3 Torr Fourth floor 12 Å ALD
Nucleation layer
B ₂ H ₆ / WF ₆
3 Torr Bulk W by sequential CVD
WF ₆ / H ₂
10 Torr Bulk W by sequential CVD
WF ₆ / H ₂
10 Torr Fifth floor Bulk W by sequential CVD
WF ₆ / H ₂
10 Torr

As shown in FIG. 9, the fluorine concentration for the films deposited using a combination of fluorine free tungsten, low pressure nucleation layer, and sequential CVD has a lower fluorine diffusion (when the depths are greater than 425 A, the W / TiN interface beyond lines 911 and lines 913). The fluorine concentration near the nucleation layer was the lowest at 300 A to 425 A for a film with more fluorine pre-tungsten deposited on the substrate, but was deposited using sequential CVD and low pressure nucleation without a fluorine pre-tungsten layer Bulk tungsten for the film has a lower fluorine concentration at about 50 A to 300 A (see line 912). These results imply that the combination of deposition of fluorine pre-tungsten and sequential CVD of tungsten may result in tungsten films that achieve very low fluorine concentrations and reduced fluorine diffusion.

Experiment 5

Experiments were conducted on process films deposited by sequential CVD in combination with low pressure nucleation layer deposition versus high pressure nucleation layer deposition. One substrate contained a tungsten nucleation layer deposited using ALD alternating cycles of WF ₆ and B ₂ H ₆ at 10 Torr and was deposited on the substrate as described above using alternating pulses of WF ₆ and H ₂ at 10 Torr As well as bulk CVD tungsten deposition according to Figure 2b. The stress and resistivity of the film were measured at various thicknesses and are shown as line 1001 "low pressure nucleation" in Figs. 10A and 10B. Another substrate contained a deposited tungsten nucleation layer using ALD alternating cycles of WF ₆ and B ₂ H ₆ at 40 Torr and was etched using alternating pulses of WF ₆ and H ₂ at 10 Torr Lt; RTI ID = 0.0 > CVD < / RTI > by sequential CVD according to FIG. The stress and resistivity of the film were measured at various thicknesses and are shown as lines 1002 "high pressure nucleation" in FIGS. 10A and 10B. The conditions for nucleation layer deposition and bulk layer deposition are shown in Table 5.

Experiment 5 Conditions 1001 Low pressure Nucleation 1002 High pressure Nucleation Nucleation layer ALD
B ₂ H ₆ / WF ₆
10 Torr ALD
B ₂ H ₆ / WF ₆
40 Torr Bulk tungsten layer Sequential CVD
WF ₆ / H ₂
10 Torr Sequential CVD
WF ₆ / H ₂
10 Torr Temperature 300 ° C

As shown in the results, the substrate with the nucleation layer deposited at low pressure had significantly lower stress than the substrate with the nucleation layer deposited at high pressure, but the resistivity was nearly the same.

Experiment 6

Experiments have been conducted on process films deposited by sequential CVD in combination with low temperature nucleation layer deposition versus high temperature nucleation layer deposition. One substrate contained a tungsten nucleation layer deposited using ALD alternating cycles of WF ₆ and B ₂ H ₆ at 10 Torr and 250 ° C and using alternating pulses of WF ₆ and H ₂ at 10 Torr And a bulk tungsten deposition by sequential CVD according to Figure 2b as described above. The stresses and resistivities of the films were measured at various thicknesses and are shown as line 1102 "low T nucleation" in FIGS. 11A and 11B. Another substrate contained a tungsten nucleation layer deposited using ALD alternating cycles of WF ₆ and B ₂ H ₆ at 10 Torr and 300 ° C and employing alternating pulses of WF ₆ and H ₂ at 10 Torr Lt; RTI ID = 0.0 > CVD < / RTI > by sequential CVD according to FIG. The stresses and resistivities of the films were measured at various thicknesses and are shown as line 1104 "high T nucleation" in FIGS. 11A and 11B. The conditions for nucleation layer deposition and bulk layer deposition are shown in Table 6.

Experiment 6 Conditions 1102 Low temperature Nucleation 1104 High temperature Nucleation Nucleation  layer ALD
B ₂ H ₆ / WF ₆
10 Torr
250 ℃ ALD
B ₂ H ₆ / WF ₆
10 Torr
300 ° C Bulk tungsten layer Sequential CVD
WF ₆ / H ₂
10 Torr Sequential CVD
WF ₆ / H ₂
10 Torr

As shown in the results, the substrate with the nucleation layer deposited at a low temperature had significantly lower stress than the substrate with the nucleation layer deposited at a higher temperature, but the resistivity of the film deposited at a higher temperature was lower The resistivity of the film was slightly lower. These results imply that the lower temperature deposition of the nucleation layer in combination with sequential CVD bulk deposition can significantly reduce the film stress.

conclusion

While the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and devices of the present embodiments. Accordingly, the embodiments are to be considered as illustrative rather than restrictive, and the embodiments are not limited to the details given herein.

Claims (22)

In a method of filling a feature,
(a) exposing the substrate in a chamber to alternating pulses of a reducing agent and a first tungsten-containing precursor to deposit a tungsten nucleation layer on the substrate; And
(b) exposing the substrate to alternating pulses of hydrogen and a second tungsten-containing precursor to deposit a bulk tungsten layer over the tungsten nucleation layer,
Wherein the chamber pressure during step (a) is 10 Torr or less. The method according to claim 1,
(c) exposing the substrate to a reducing agent and a third tungsten-containing precursor simultaneously to deposit a second bulk tungsten layer. 3. The method of claim 2,
(d) performing the step (c) for every two or more cycles of the step (b), wherein the cycle of step (b) comprises applying a pulse of hydrogen and a pulse of the second tungsten- Including a method of filling a feature. 4. The method according to any one of claims 1 to 3,
Wherein step (b) is performed with cycles comprising a pulse of hydrogen and a pulse of the tungsten-containing precursor, and each of the cycles forming a submonolayer having a thickness of at least about 0.3 A How to fill. 4. The method according to any one of claims 1 to 3,
Wherein the first tungsten-containing precursor differs from the second tungsten-containing precursor. 6. The method of claim 5,
Wherein the first tungsten-containing precursor is fluorine-free. 4. The method according to any one of claims 1 to 3,
Wherein the deposited tungsten nucleation layer and the deposited bulk tungsten layer have a tensile stress of less than about 1 micron per deposited 500 angstroms. A method of depositing tungsten on a substrate,
The method comprises:
(a) depositing a tungsten layer on the substrate; And
(b) depositing the bulk tungsten layer in cycles,
Wherein depositing the tungsten layer on the substrate comprises:
(i) exposing the substrate to a reducing agent, and
(ii) exposing the substrate to a first fluorinated tungsten-containing precursor,
The cycle
(i) exposing the substrate to hydrogen (H _2),
(ii) exposing the substrate to a second tungsten-containing precursor, and
(iii) repeating steps (i) and (ii) in one or more cycles to deposit the bulk tungsten layer. 9. The method of claim 8,
Wherein the first fluorine free tungsten-containing precursor is selected from the group consisting of metal-organic tungsten-containing precursors and tungsten hexacarbonyl. 10. The method according to claim 8 or 9,
Wherein the tungsten layer of step (a) is deposited to a thickness of from about 2 A to about 100 A. 10. The method according to claim 8 or 9,
Wherein each of the cycles of step (b) forms a sub-mono layer having a thickness of at least about 0.3 Angstroms. In a method of filling a feature,
(a) exposing the substrate to alternating pulses of hydrogen and a first tungsten-containing precursor to deposit a bulk tungsten layer on the substrate; And
(b) exposing the substrate to a second tungsten-containing precursor and a reducing agent simultaneously to deposit a second bulk tungsten layer on the substrate. 13. The method of claim 12,
Wherein the step (a) and the step (b) are sequentially repeated. 13. The method of claim 12,
Wherein the tungsten-containing precursor of step (b) is a fluorine-free tungsten-containing precursor selected from the group consisting of metal-organic tungsten-containing precursors, tungsten chlorides, and tungsten hexacarbonyl. 15. The method according to any one of claims 12 to 14,
Wherein the first tungsten-containing precursor differs from the second tungsten-containing precursor. An apparatus for processing substrates,
The apparatus comprises:
(a) at least one process chamber including a pedestal configured to hold the substrate;
(b) at least one outlet for coupling with a vacuum;
(c) one or more process gas inlets coupled to the one or more process gas sources; And
(d) a controller for controlling operations in the device,
The controller comprising:
(i) machine-readable instructions for introducing a reducing agent and a first tungsten-containing precursor into alternating pulses in the process chamber; And
(ii) machine-readable instructions for introducing hydrogen and a second tungsten-containing precursor into alternating pulses in the process chamber,
Wherein the chamber pressure during the machine-readable instruction (i) is 10 Torr or less. 17. The method of claim 16,
Wherein the controller further comprises: (iii) machine-readable instructions for simultaneously introducing a reducing agent and a third tungsten-containing precursor to the process chamber to deposit a second bulk tungsten layer. 17. The method of claim 16,
(Iv) further comprises machine-readable instructions for performing the machine-readable instructions (iii) for every two or more cycles of the machine-readable instructions (ii), the machine-readable instructions wherein said cycle of step (ii) comprises a pulse of hydrogen and a pulse of said second tungsten-containing precursor. 19. The method according to any one of claims 16 to 18,
Wherein the first tungsten-containing precursor differs from the second tungsten-containing precursor. 19. The method according to any one of claims 16 to 18,
Wherein the first tungsten-containing precursor is fluorine-free. An apparatus for processing substrates,
The apparatus comprises:
(a) at least one process chamber including a pedestal configured to hold the substrate;
(b) at least one outlet for coupling with a vacuum;
(c) one or more process gas inlets coupled to the one or more process gas sources; And
(d) a controller for controlling operations in the device,
The controller comprising:
(i) machine-readable instructions for introducing hydrogen and a first tungsten-containing precursor into alternating pulses in the process chamber to deposit a bulk tungsten layer; And
(ii) machine-readable instructions for simultaneously introducing a second tungsten-containing precursor and a reducing agent into the process chamber to deposit a second bulk tungsten layer. 22. The method of claim 21,
Wherein the controller further comprises machine-readable instructions for sequentially iterating the machine-readable instructions (i) and (ii).

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