Atomic Layer Deposition on 3D NAND Structures

Abstract

Methods and apparatus for providing low roughness tungsten deposition are described. In some embodiments, the methods involve flowing nitrogen with hydrogen during an atomic layer deposition process for depositing tungsten, using hydrogen as a reducing agent. In some embodiments, the methods involve depositing a cap layer, such as a tungsten oxide layer or an amorphous tungsten layer, on the sidewall surfaces of a 3D NAND structure. The disclosed embodiments have broad applications, including depositing tungsten into 3D NAND structures.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] The PCT application form is filed contemporaneously herewith as a part of this application. Each application to which this invention claims benefit or priority, as identified in the contemporaneously filed PCT application form, is hereby incorporated by reference in its entirety for all purposes. [Background technology]

[0002] Depositing tungsten-containing materials is an essential part of many semiconductor fabrication processes. These materials may be used for horizontal interconnects, vias between adjacent metal layers, and contacts between metal layers and devices. However, as devices shrink and the industry utilizes more complex patterning schemes, depositing thin tungsten films becomes a challenge. Deposition in complex high aspect ratio structures such as 3D NAND structures is particularly challenging.

[0003] The background description provided herein is intended to generally present the context of the present disclosure. To the extent described in this Background section, neither the works of the inventors named herein, nor aspects of the description that may not otherwise be considered prior art at the time of submission, are admitted, either explicitly or implicitly, as prior art to the present disclosure. Summary of the Invention

[0004] One aspect of the disclosure relates to a method that includes providing a structure to be filled with a tungsten-containing material and exposing the structure to a number of deposition cycles, each deposition cycle including sequentially delivering a dosage of hydrogen (H) flowing with nitrogen (N) and a dosage of a tungsten precursor to a chamber containing the structure.

[0005] In some embodiments, the structure is a partially fabricated three-dimensional (3-D) NAND structure including a sidewall and a plurality of openings in the sidewall, the plurality of openings leading to a plurality of features having a plurality of interior regions accessible by fluid through the openings. In some embodiments, the dose of the tungsten precursor is delivered at a pressure of at least 300 Torr. In some embodiments, the dose of the tungsten precursor is delivered without nitrogen. In some embodiments, N2 is between 10% and 30% (by volume) of the total N2+H2 flow. In some embodiments, the substrate temperature is 350° C. or less during the dose of H2 flowing with N2. In some embodiments, N2 is more than 30% (by volume) of the total N2+H2 flow and the substrate temperature is at least 375° C. during the dose of H2 flowing with N2. In some embodiments, the tungsten precursor is tungsten hexafluoride. In some embodiments, the tungsten precursor is a chlorine-containing tungsten precursor. In some embodiments, the dose of the tungsten precursor is delivered at a higher pressure than the dose of H2 flowing with N2.

[0006] Another aspect of the disclosure relates to a method that includes providing a structure having gaps to be filled with a tungsten-containing material and exposing the structure to multiple deposition cycles, each deposition cycle including sequentially delivering a dosage of hydrogen (H) and a dosage of a tungsten precursor to deposit a bulk tungsten film in the gaps and forming a cap layer on the bulk layer.

[0007] In some embodiments, the structure is a partially fabricated three-dimensional (3-D) NAND structure including sidewalls and a number of openings in the sidewalls leading to gaps that are filled with tungsten. In some embodiments, the cap layer is a tungsten oxide layer. In some embodiments, the cap layer is an amorphous tungsten layer. In some embodiments, the structure is provided in a multi-station deposition chamber, where multiple deposition cycles are performed at one or more first stations of the multi-station deposition chamber, and the cap layer is formed at one or more second stations of the multi-station deposition chamber. In some embodiments, the cap layer is deposited on the sidewalls.

[0008] Another aspect of the present disclosure is a method that includes: (a) depositing a tungsten nucleation layer in a feature on a substrate by alternating pulses of a tungsten precursor and a boron-containing reducing agent, (b) depositing a tungsten template layer on the tungsten nucleation layer by alternating pulses of a tungsten precursor and hydrogen (H2) at a substrate temperature between 250° C. and 350° C., (c) after (b), increasing the substrate temperature by at least 50° C., and (d) after (c), depositing a tungsten bulk layer by alternating pulses of a tungsten precursor and hydrogen (H2) at a substrate temperature of at least 350° C. In some embodiments, the tungsten nucleation layer is deposited to a thickness of 30 Angstroms or less.

[0009] Yet another aspect of the present disclosure relates to an apparatus that includes a process chamber having one or more stations each configured to hold a substrate, one or more process gas inlets for coupling to a hydrogen (H) gas source, a nitrogen (N) gas source, and a tungsten precursor gas source, and a controller for controlling operation within the apparatus, the controller including machine readable instructions for sequentially delivering a dosage of hydrogen (H) and a dosage of tungsten precursor flowing with the nitrogen (N) to the process chamber.

[0010] These and other aspects are further described below with reference to the drawings. [Brief description of the drawings]

[0011] [Figure 1A] 1 presents a cross-sectional side view of a 3-D NAND structure that may be filled with tungsten according to embodiments described herein.

[0012] [Figure 1B] FIG. 1A presents a cross-sectional top view of a-D NAND.

[0013] [Figure 2A] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments. [Figure 2B] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments.

[0014] [Figure 2C] FIG. 2 is a timing sequence diagram illustrating an example of a cycle in a method for depositing a film in accordance with certain disclosed embodiments.

[0015] [Diagram 3] 1 presents a cross-sectional side view of filled wordline features of a 3-D NAND structure.

[0016] [Figure 4] FIG. 2 is a timing sequence diagram illustrating an example of a cycle in a method for depositing a film in accordance with certain disclosed embodiments.

[0017] [Figure 5A] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments. [Figure 5B] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments. [Figure 5C] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments. [Figure 5D] 1 is a process flow diagram illustrating operations for methods in accordance with certain disclosed embodiments.

[0018] [Figure 6] FIG. 1 is a schematic diagram of an example processing tool for carrying out certain disclosed embodiments.

[0019] [Figure 7] FIG. 1 is a schematic diagram of an example station for implementing certain disclosed embodiments.

[0020] [Figure 8] FIG. 1 is a schematic diagram illustrating basic features of a manifold system that may be used, according to certain embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In the following description, numerous specific details are set forth to enable a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known processing operations have not been described in detail in order to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that they are not intended to be limited to the disclosed embodiments.

[0022] Semiconductor device fabrication often uses tungsten (W) filling of features to form electrical contacts. In conventional methods of depositing tungsten films, a nucleation tungsten layer is first deposited into a via or contact. Generally, the nucleation layer is a conformal thin layer that helps facilitate subsequent formation of bulk material over it. The tungsten nucleation layer may be deposited to conformally coat the sidewalls and bottom of the feature. Conforming to the bottom and sidewalls of the underlying feature can be crucial to aid in high quality deposition. Often, the nucleation layer is deposited using atomic layer deposition (ALD) or pulsed nucleation layer (PNL) techniques.

[0023] In ALD or PNL techniques, pulses of reactants are injected sequentially and typically purged from the reaction chamber by pulses of purge gas between reactants. The first reactant is allowed to adsorb onto the substrate and is available to react with the next reactant. This process is repeated in a cyclical manner until a desired thickness is achieved. In the context of the disclosed embodiments, chemical vapor deposition (CVD) embodies a process in which reactants are introduced together into a reactor during gas-phase or surface reactions. PNL and ALD processes are separate from CVD processes and vice versa.

[0024] After depositing the tungsten nucleation layer, bulk tungsten may be deposited by a CVD process by reducing tungsten hexafluoride (WF6) using a reducing agent such as hydrogen (H2). Bulk tungsten is different from a tungsten nucleation layer. Bulk tungsten, as used herein, refers to tungsten used to fill most or all of a feature, such as at least about 50% of the feature. Unlike a nucleation layer, which is a conformal thin film that helps to facilitate the subsequent formation of bulk material on top, bulk tungsten is used to carry current. Bulk tungsten may be characterized by larger grain size and lower resistivity compared to a nucleation film. In various embodiments, bulk tungsten is tungsten deposited to a thickness of at least 50 Å.

[0025] As devices are scaled to smaller technology nodes and use more complex patterned structures, tungsten fill presents various challenges. One challenge is to deposit conformally within these structures such that there is a uniform distribution of material throughout the structure. The distribution of material within a feature or structure may be characterized by the step coverage of the material distribution. For purposes of this specification, "step coverage" is defined as the ratio of two thicknesses. For example, step coverage may be the thickness of material inside the feature divided by the thickness of material near the opening. For purposes of this document, the term "inside the feature" refers to a central portion of the feature centered about the midpoint of the feature along the axis of the feature, e.g., an area between about 25%-75% of the distance, or in some embodiments, an area between about 40%-60% of the distance along the depth of the feature measured from the opening of the feature, or a terminal portion of the feature located between about 75%-95% of the distance along the axis of the feature as measured from the opening. The term "near the opening of the feature" or "near the feature's opening" refers to the top portion of a feature that is located within 25%, or more specifically, within 10%, of the edge of the opening or other elements that represent the edge of the opening. Greater than 100% step coverage can be achieved, for example, by filling a wider feature in the center or near the bottom of the feature than at the feature opening.

[0026] Another challenge is to reduce the concentration or content of fluorine in the deposited tungsten film. When compared to larger features, smaller features in the tungsten film with the same fluorine concentration as the larger features have a substantially greater impact on device performance. For example, the smaller the feature, the thinner the film deposited. As a result, fluorine in the deposited tungsten film is more likely to diffuse through the thinner film, potentially causing device failure. For structures such as 3D NAND structures, sidewall roughness is also a challenge.

[0027] The methods and apparatus provided herein have one or more of the following advantages: In some implementations, the methods and apparatus provide tungsten deposition with reduced roughness. The methods and apparatus may do so without an intervening etching operation by providing smoother growth. Low fluorine tungsten may be deposited. Additionally, the methods may provide good step coverage. The disclosed embodiments have a wide range of applications, including depositing tungsten into 3D NAND structures.

[0028] The methods described herein are performed on a substrate that may be contained within the chamber. The substrate may be a silicon wafer or other semiconductor wafer, for example a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, including wafers having one or more layers of material, such as a dielectric material, a conductive material, or a semiconductor material, deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fill any feature with a metal, such as tungsten.

[0029] FIG. 1A presents a cross-sectional side view of a 3-D NAND (also called vertical NAND or VNAND) structure 110 (formed on a semiconductor substrate 103) having VNAND stacks (125 on the left and 126 on the right), a central vertical structure 130, and a number of stacked horizontal features 120 with openings 122 on opposing sidewalls 140 of the central vertical structure 130. FIG. 1F displays two stacks 125 and 126 of the illustrated 3-D NAND structure 110 that together form a trench-like central vertical structure 130; however, it should be noted that in certain embodiments, there may be three or more stacks arranged in sequence that run parallel to each other in space, with the gap between each adjacent pair of stacks forming the central vertical structure 130, as explicitly illustrated in FIG. 1A. In the example of FIG. 1A, the horizontal features 120 are 3-D memory wordline features that are fluidly accessible from the central vertical structure 130 through the openings 122. Although not explicitly shown in the figures, the horizontal features 120 present in both 3-D NAND stacks 125 and 126 shown in FIG. 1A (i.e., the left 3-D NAND stack 125 and the right 3-D NAND stack 126) are also reachable from the other side of the stack (at the left and right ends, respectively) through similar vertical structures formed by additional 3-D NAND stacks (leading to the left and right ends, not shown). In other words, each 3-D NAND stack 125, 126 contains a stack of wordline features that are fluidly reachable from both sides of the 3-D NAND stack through a central vertical structure 130.

[0030] Wordline features in a 3-D NAND stack are typically formed by depositing an alternating stack of silicon oxide and silicon nitride layers and then selectively removing the nitride layers, leaving a stack of oxide layers 142 with gaps between the silicon oxide and silicon nitride layers. These gaps are the wordline features. Any number of wordlines may be stacked vertically in such a 3-D NAND structure, so long as techniques are available not only to form any number of wordline features, but also to successfully achieve (substantially) void-free filling of the vertical features. Thus, for example, a VNAND stack may include between 2 and 256 horizontal wordline features, or between 8 and 128 horizontal wordline features, or between 16 and 64 horizontal wordline features, etc. (it is understood that the recited ranges include the recited endpoints).

[0031] FIG. 1B presents a cross-sectional top view of the same 3-D NAND structure 110 shown in side view in FIG. 1A, taken through a horizontal cross section 160 as indicated by the horizontal dotted line in FIG. 1A. The cross section in FIG. 1G illustrates several rows of pillars 155 shown in FIG. 1A extending vertically from the base of the semiconductor substrate 103 to the top of the 3-D NAND stack 110. In some embodiments, these pillars 155 are formed from polysilicon material and are structurally and functionally important to the 3-D NAND structure 110. In some embodiments, such polysilicon pillars may act as gate electrodes for stacked storage cells formed within the pillars. The top view in FIG. 1B illustrates that the pillars 155 form a constriction within the opening 122 to the word line feature 120, i.e., fluid accessibility from the central vertical structure 130 through the opening 122 to the word line feature 120 (as indicated by the arrow in FIG. 1G) is prohibited by the pillars 155. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is between about 1 nm and 20 nm. This reduced fluid accessibility increases the difficulty of uniformly filling the wordline features 120 with tungsten material.

[0032] 2A-2C describe methods that may be performed to fill a 3D NAND structure with low fluorine and low resistivity tungsten. Turning first to FIG. 2A, 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 the subsequent bulk deposition in operation 280. For example, operations 202-210 may be performed at a low pressure of less than about 10 Torr. In some examples, operations 202-210 are performed at a pressure of about 10 Torr, or at a pressure of about 3 Torr.

[0033] In some implementations, performing operations 202-210 at low pressure reduces the fluorine concentration in the deposited tungsten film due to a lower partial pressure of the fluorine-containing precursor in the chamber when depositing the film, resulting in less fluorine being incorporated into the film.

[0034] In operation 202, the substrate is exposed to a tungsten-containing precursor, such as WF6. For purposes of description herein, WF6 is used as an example of a tungsten-containing precursor, but it should be understood that other tungsten-containing precursors may be suitable for carrying out the disclosed embodiments. For example, organometallic tungsten-containing precursors may be used. Organometallic precursors may also be used, as well as fluorine-free precursors such as MDNOW (methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW (ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten). Tungsten chloride (WCl x ) and tungsten hexacarbonyl W(CO). Tungsten-containing precursors may include combinations of these compounds. In some embodiments, a carrier gas such as nitrogen (N), argon (Ar), helium (He), or other inert gas may be flowed during operation 202.

[0035] Operation 202 may be performed for any suitable duration and at any suitable temperature. In some examples, operation 202 may be performed for a duration between about 0.25 seconds and about 30 seconds, about 0.25 seconds to about 5 seconds, or about 0.5 seconds to about 3 seconds. In some embodiments, the operation may be performed for a duration sufficient to saturate the active sites on the substrate surface.

[0036] In operation 204, the chamber is optionally purged to remove excess WF6 that has not been adsorbed onto the substrate surface. Purging may be performed by flowing an inert gas at a fixed pressure, thereby reducing the chamber pressure, and repressurizing the chamber before starting another gas exposure.

[0037] In operation 206, the substrate is exposed to a reducing agent to deposit a tungsten nucleation layer. The reducing agent may be a borane, a silane, or a germane. Examples of boranes include borane (BH3), diborane (B2H6), triborane, alkylboranes, aminoboranes, carboboranes, and haloboranes. Examples of silanes include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), alkylsilanes, aminosilanes, carbosilanes, and halosilanes. Germanes 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 is different from m. Other germanes may also be used, for example, alkylgermanes, aminogermanes, carbogermanes, and halogermanes. In general, halogermanes may not have a significant reduction potential, but suitable processing conditions and tungsten-containing precursors may exist for forming films using halogermanes.

[0038] Operation 206 may be performed for any suitable duration. In some examples, example durations may include between about 0.25 seconds and about 30 seconds, about 0.25 seconds to about 5 seconds, or about 0.5 seconds to about 3 seconds. In some embodiments, the operation may be sufficient to react with an adsorbed layer of WF6 on the substrate surface. Operation 206 may be performed for durations exceeding these example ranges. In some embodiments, a carrier gas such as, for example, argon (Ar), helium (He), or nitrogen (N2) may be used.

[0039] After operation 208, there may be an optional purge step to purge excess reducing agent still in the gas phase that did not react with WF6 on the surface of the feature. Purging may be performed by flowing an inert gas at a fixed pressure, thereby reducing the pressure in the chamber and repressurizing the chamber before starting another gas exposure.

[0040] In operation 210, it is determined whether the tungsten nucleation layer has been deposited to an appropriate thickness. If not, operations 202-208 are repeated until a tungsten nucleation layer of the desired thickness is deposited on the surface of the feature. Each repetition 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, such that the reducing agent is introduced first.

[0041] After the tungsten nucleation layer is deposited to an appropriate thickness, bulk tungsten is deposited in operation 280, as described below. In various embodiments, operation 280 may be performed at a pressure greater than the pressure during operations 202-210. For example, operation 280 may be performed at a pressure of about 10 Torr or greater, such as about 10 Torr or about 40 Torr. In some embodiments, the pressure during both the nucleation layer deposition and the bulk layer deposition may be about 5 Torr to 20 Torr, or 10 Torr.

[0042] Figure 2B provides a process flow diagram for operations that may be performed during operation 280. Note that the operations of Figure 2B may be performed without performing the operations of Figure 2A. Figure 2C provides a timing sequence diagram illustrating an example ALD cycle of process 200.

[0043] In FIG. 2B, in operation 282, the substrate is exposed to a reducing agent such as H2. This operation may be referred to as a "pulse" or a "dose," which may be used interchangeably herein. The H2 is pulsed without flowing another reactant. In some embodiments, a carrier gas may be flowed. The carrier gas may be any of the carrier gases described above with respect to operation 204 in FIG. 2A. Operation 282 may be performed for any suitable duration. In some examples, example durations may include between about 0.25 seconds and about 30 seconds, about 0.25 seconds to about 5 seconds, or about 0.5 seconds to about 3 seconds.

[0044] Figure 2C shows H2 dosage 220A in deposition cycle 211A, which may correspond to operation 282 of Figure 2B. During H2 dosage 220A, the carrier gas is flowed, the reducing agent is pulsed, and the WF6 flow is turned off.

[0045] Returning to FIG. 2B, in operation 284, the chamber is purged. This purge operation may remove excess H2 remaining in gas phase form. Purging is performed by flowing an inert gas at a fixed pressure, thereby reducing the chamber pressure, and repressurizing the chamber before starting another gas exposure. The chamber may be purged for any suitable duration, for example, for a duration between about 0.1 seconds and about 3 seconds. Operation 284 of FIG. 2B may correspond to purge stage 240A of FIG. 2C. As shown in FIG. 2C, during purge stage 240A, the carrier gas is flowed, but the H2 and WF6 flows are turned off.

[0046] Returning to FIG. 2B, in operation 286, the substrate is exposed to a tungsten-containing precursor (e.g., WF6) to form a sub-monolayer or monolayer of a film on the substrate. In various embodiments, WF6 is flowed into the chamber during this operation for a duration between about 0.1 seconds and about 3 seconds, or about 0.5 seconds. In some embodiments, WF6 is delivered to fill gas lines and line switches before dosing. In some embodiments, WF6 is flowed into the chamber but does not completely react with all H2 molecules on the substrate surface. Operation 286 may correspond to WF6 dosing 260A in FIG. 2C. As shown in FIG. 2C, during WF6 dosing 260A, the carrier gas is flowed, the H2 flow is turned off, and the WF6 flow is turned on.

[0047] In operation 288 of FIG. 2B, the chamber is purged to remove reacted by-products and gas phase WF6 from the chamber. In some embodiments, the purge duration may be between about 0.1 seconds and about 2 seconds to prevent removing all of the WF6 from the substrate surface due to the low adsorption rate of WF6 on the tungsten surface. In some embodiments, the purge duration may be between about 0.1 seconds and about 15 seconds, such as about 7 seconds. For example, to fabricate a 3D NAND structure, the chamber may be purged for about 7 seconds during operation 288. The purge duration depends on the substrate and the stress.

[0048] Operation 288 of Figure 2B may correspond to the purge stage 270A of Figure 2C. As shown in Figure 2C, the purge stage 270A completes the deposition cycle 211A. In some embodiments, operations 286 and 282 may be reversed, such that operation 286 is performed before 282. In some embodiments, operation 282 may be performed before operation 286.

[0049] In act 290 of FIG. 2B, it is determined whether bulk tungsten has been deposited to an adequate thickness. If not, acts 282-288 are repeated until the desired thickness is deposited. In some embodiments, acts 282-288 are repeated until the feature is filled. In FIG. 2C, it is determined that bulk tungsten has not been deposited to an adequate thickness, so acts 282-288 of FIG. 2B are repeated in deposition cycle 211B, resulting in H2 dosing 220B being performed, followed by purge phase 240B. WF6 dosing 260B is performed, followed by purge phase 270B.

[0050] The disclosed embodiments may have various applications in tungsten deposition processes. For example, in some embodiments, 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 WF6, followed by bulk tungsten deposition by using ALD cycles of alternating pulses of H2 and WF6. In some embodiments, the tungsten nucleation layer may be omitted, and bulk deposition as described above with reference to Figures 2B and 2C is performed directly on the underlying feature or layer. Tungsten films deposited using the disclosed embodiments have low fluorine concentration, low stress, good step coverage, and low resistivity.

[0051] In some aspects, the methods described herein provide smooth films with low roughness. In a 3D NAND structure, for example, the sidewalls 140 of the 3D NAND stacks 125, 126 have tungsten at the opening of each tungsten wordline deposited in each horizontal feature 120. This is shown at 346 in FIG. 3 for a single wordline 320. The tungsten at 346 covers the sidewalls 340 of the stack including the wordline 320 and oxide layer 342, and is etched back in subsequent processing. However, the roughness of the sidewalls can lead to an uneven profile after etchback, which can eventually cause the etching chemicals to diffuse into the wordline, leading to device failure.

[0052] CVD techniques may provide smooth sidewall coverage, but step coverage and conformality inside the feature may be lacking. Provided herein is an ALD method that provides low roughness that may be implemented using the processes described above with reference to Figures 2A-2C. The ALD method described herein can reduce the surface diffusion of W adatoms that leads to shoulder drop and roughness outside the gap, such as in the 3D-NAND center trench.

[0053] In some embodiments, the method involves flowing nitrogen (N2) along with the reducing agent in operation 282 of FIG. 2B. FIG. 4 provides a timing sequence diagram illustrating an example of an ALD cycle of process 400. The timing sequence diagram is similar to that of FIG. 2B with the addition of co-flowing N2 during H dosing. In particular, FIG. 4 shows H2+N2 dosing 420A in deposition cycle 411A, which may correspond to operation 282 of FIG. 2B. During H2 dosing 420A, carrier gas is flowed, H2 and N2 are pulsed, and WF6 flow is turned off. Deposition cycle 411A further includes WF6 dosing 460A and a purge stage 470A, as described above with reference to FIG. 2C. These operations are repeated in subsequent deposition cycles as shown at 420B, 440B, 460B, and 470B. Sidewall roughness is significantly reduced using the timing sequence shown in FIG. 4 compared to a timing sequence without nitrogen flow during H2 operation. In particular, the timing sequence shown in Figure 4 was found to reduce sidewall roughness by approximately half. This can be attributed to the addition of N2 on the surface inhibiting diffusion of adsorbed W atoms (W adatoms) and suppressing tungsten growth at the feature corners. Notably, flowing N2 during the reducing agent dose was found to reduce roughness more than flowing it during the tungsten precursor pulse.

[0054] According to various embodiments, N2 may represent about 10%-30% (by volume) of the total N2+H2 flow. Higher N2 flows may be used, which may lead to even less roughness, but may lead to increased film resistivity and / or stress. Stress increase can be prevented or avoided by using relatively high temperatures, e.g., 375° C. or higher, such as 400° C.

[0055] In some embodiments, roughness is improved by using an ALD process with a chamber pressure of at least 20 Torr or 25 Torr in FIG. 2B. For example, deposition cycles 200 and 400 may be performed at about 25 Torr as shown in FIG. 2C and FIG. 4, respectively. This shows an improvement of over 10 Torr, which is attributed to a reduction in W adatom diffusion distance. To reduce roughness, the chamber pressure may be between 20 Torr and 40 Torr. At pressures higher than 40 Torr, step coverage may be compromised as the process may become too CVD-like and purging may be difficult.

[0056] In some embodiments, the tungsten precursor is delivered at a high dosing pressure during operation 286. As described below, gas lines may be flooded to deliver each reactant. Delivering the tungsten precursor at a high flood pressure, for example at least 300 Torr or about 400 Torr, results in less roughness. This may be due to higher adsorption on the surface, which limits atomic adsorption diffusion. In some embodiments, the tungsten precursor is delivered at a pressure between 400 Torr and 700 Torr.

[0057] Table 1 below shows the roughness reduction achieved for different processing conditions that fall within the scope of this disclosure. Tungsten was deposited in a 3-D NAND structure to fill wordline features and the sidewall roughness was measured. [Table 1]

[0058] Flowing N2 with WF6 at elevated temperatures can reduce sidewall roughness. For example, flowing N2 with WF6 (or other precursors) at temperatures above 400°C has been shown to reduce roughness from 7.4 nm to 3.5 nm. N2 can be from 10% to 90% by volume of the total N2+WF6 flow, with higher N2 resulting in less roughness without degrading film properties. At lower temperatures (e.g., 300°C), the roughness may not improve. This is in contrast to other methods mentioned above, which can reduce roughness at lower temperatures such as 300°C.

[0059] FIG. 5A is a process flow diagram illustrating another method of filling a structure having gaps with tungsten. In some embodiments, the structure is a 3D NAND structure as shown in FIG. 1A. The method begins with operation 502, depositing a tungsten nucleation layer to conformally cover the structure with tungsten. Operation 502 may be performed as described above with reference to operations 202-210 of FIG. 2A. In some embodiments, a silicon-containing reducing agent and / or a boron-containing reducing agent is used during the tungsten nucleation layer deposition. In some embodiments, operation 502 may be omitted as described above. Next, in operation 504, a bulk tungsten layer is deposited by ALD to fill the gaps in the structure. Operation 504 may be performed as described above with reference to operations 282-290 of FIG. 2A and / or timing sequence diagrams 200 and 400 of FIG. 2C and FIG. 4, respectively. However, rather than continuing deposition (e.g., at 346 in the example of FIG. 4) and allowing deposition to occur outside the feature, deposition is stopped at operation 506. At this point, the inside of the wordline feature may be completely filled. A cap layer is then formed over the bulk tungsten at operation 508. The cap layer is a relatively thin layer, i.e., thinner than the bulk tungsten layer, and may be deposited by CVD or ALD in some embodiments. Example thicknesses range from 100 Angstroms to 200 Angstroms. Examples of cap layers include amorphous tungsten layers and tungsten oxide layers. The cap layer may be formed only outside the wordline feature.

[0060] In some embodiments, block 508 involves CVD deposition of a cap layer on the sidewalls of the 3D-NAND structure. CVD deposition on the 3D-NAND structure improves sidewall smoothness because of the faster deposition rate of CVD deposition, which allows less time for W adatom surface diffusion. Thus, the transition from block 506 to block 508 may involve a transition from alternating pulses of tungsten precursor and (hydrogen or other reducing agent) to simultaneously introducing the tungsten precursor and reducing agent into the deposition chamber.

[0061] In some embodiments, block 508 involves forming a tungsten oxide cap layer on the sidewalls of the 3D-NAND structure. This involves depositing a relatively thin ALD layer of tungsten, then exposing the structure to air to oxidize the layer, and then repeating, for example according to the timing sequence diagrams of Figure 2C or Figure 4. For example, block 508 may involve ALD deposition of about 20 angstroms of tungsten, oxidation, and repeating to form 100 angstroms to 200 angstroms of tungsten oxide.

[0062] In some embodiments, block 508 may involve the deposition of an ALD tungsten layer formed by a method such as that described above with respect to FIG. 2A. The cap layer is not a "nucleation" layer in the sense that there is typically no bulk deposition thereon, but it is smoother than the bulk layer. An ALD tungsten layer deposited with a silane or boron reducing agent and a tungsten precursor may be an amorphous tungsten layer.

[0063] Table 2 below shows the roughness reduction achieved for different capping layers falling within the scope of this disclosure. Tungsten was deposited in a 3-D NAND structure to fill the wordline features and the sidewall roughness was measured. [Table 2]

[0064] It should be noted that the higher resistivity of the cap layer is tolerable since the cap layer is removed during a subsequent etching operation.

[0065] FIG. 5B is a process flow diagram illustrating another method of filling a structure having gaps with tungsten. In FIG. 5B, operations 602 and 604 may be performed as described above with respect to FIG. 5A. At 556, the crystal growth of the ALD layer is stopped. This may involve stopping the ALD deposition and performing a process to interrupt the grain growth. In some embodiments, block 558 may involve a nitrogen (N2) soak or tungsten nucleation layer deposition as described above with respect to FIG. 2A. A bulk deposition process is then performed as described above with respect to FIG. 2C and FIG. 4, however, grain growth begins anew, reducing roughness. In some embodiments, the bulk layer deposition conditions may be changed from operation 504 to operation 558. For example, operation 504 may involve a timing diagram as described in FIG. 2C without co-flowing nitrogen, and adding nitrogen as in FIG. 4 for operation 558. Similarly, the chamber pressure and / or tungsten delivery pressure may be increased at operation 558.

[0066] FIG. 5C is a process flow diagram illustrating a method for filling a 3D NAND structure with tungsten. The method described in FIG. 5C may also be applied to other structures having gaps to be filled. The method begins with operation 562, depositing a tungsten nucleation layer to conformally cover the wordline features with tungsten. Operation 562 may be performed as described above with reference to operations 202-210 of FIG. 2A. In some embodiments, a silicon-containing reducing agent and / or a boron-containing reducing agent is used during the tungsten nucleation layer deposition. In some embodiments, operation 502 may be omitted as described above with reference to operations 202-210 of FIG. 2A. Next, in operation 564, a bulk tungsten layer is deposited by ALD to fill the wordline features in the structure. Operation 564 may be performed as described above with reference to operations 282-290 of FIG. 2A and / or timing sequence diagram 200 of FIG. 2C. Once the wordline features are filled, in operation 566, a smooth bulk tungsten layer is deposited outside the wordline features. Operation 566 may use at least one or more of the techniques described above, namely, adding N2 to the H2 pulse, increasing the process pressure, increasing the tungsten precursor delivery pressure, depositing a cap layer, and interrupting grain growth. In some embodiments, the transition from operation 564 to operation 566 may be gradual, for example, nitrogen may be gradually added to the reducing agent pulse as the wordline feature nears completion. It should also be noted that the wordline feature may be filled at different times, and operation 566 may be implemented after some or all of the feature is filled.

[0067] FIG. 5D is a process flow diagram illustrating another method of filling a 3D NAND structure with tungsten. The method described in FIG. 5D may also be applied to other structures having gaps to be filled. The method begins with operation 582, depositing a thin tungsten nucleation layer to conformally cover the wordline features with tungsten. Operation 582 may be performed as described above with reference to operations 202-210 of FIG. 2A. In some embodiments, a silicon-containing reducing agent and / or a boron-containing reducing agent is used during the tungsten nucleation layer deposition. However, in the method of FIG. 5D, the deposited nucleation layer is thinner than that deposited by other methods. The nucleation layer range of operation 582 may be about 15-25 Å, as opposed to 25-40 Å that may be used in certain other embodiments. Reducing the nucleation thickness can effectively alter the nucleation site density, thus tuning the grain size of the crystal growth and reducing roughness. A tungsten nucleation layer of less than 20 Å may be used. However, one drawback of reducing grain size can be increased resistivity. Increased resistivity can occur due to excess boron from the presence of reducing agent in the nucleation layer if the nucleation layer is not fully converted. In some embodiments, operation 582 involves mitigating excess boron residues by increasing argon dilution and / or increasing tungsten precursor exposure time. For example, in some embodiments, the B2H6:Ar dilution is at least 1:5 or 1:9. This is increased from the 1:3 dilution used in certain other nucleation layer depositions. The dilution can be increased even further, although levels such as 1:20 may provide insufficient step coverage. In some embodiments, the dilution level is, for example, 1:5 to 1:12. In some embodiments, the tungsten precursor pulse is of longer duration than the reducing agent pulse, for example, at least 1.5 to 2 times longer duration.

[0068] In some embodiments, a thin template layer of tungsten is then deposited on the nucleation layer in operation 584. This operation may be performed in addition to or instead of limiting boron incorporation in operation 582. In some embodiments, if operation 584 effectively mitigates the resistance increase, operation 584 may be omitted. If performed, operation 584 involves ALD using pulses of WF6 (or other tungsten precursor) and reducing agent H2 at low temperatures between 250°C and 350°C, or in some embodiments, 250°C to 325°C or 250°C to 300°C. In some embodiments, temperatures below 300°C may be used. Example thicknesses of the template film may be 20 Å to 50 Å, or about 30 Å. This low temperature template layer provides a good template for large grain growth in the subsequent bulk tungsten deposition. The method then continues with depositing bulk tungsten on the template layer in operation 586. This may also be accomplished by an ALD WF6 / H2 operation (or using other tungsten precursors), but at higher temperatures, e.g., 350°C-450°C, or 375°C or higher. An example of the total tungsten deposition, including the nucleation layer, template layer, and bulk layer, may be about 300 Å. In some embodiments, for example, the deposition sequence may involve: ALD deposition of tungsten nucleation layer: WF6 / B2H6 pulses ALD deposition of template layer: WF6 / H2 pulses at 250℃-350℃ Increase the substrate temperature, for example by at least 50° C. ALD deposition of bulk layers: WF6 / H2 pulses at 350°C–450°C

[0069] The method described in Figure 5D may also be implemented in combination with any of the methods described above. For example, the step of depositing a thin tungsten nucleation layer as described above, with or without a subsequent template layer, may be accomplished in any of the ways described with reference to Figures 5A-5C.

[0070] Device Any suitable chamber may be used to implement the disclosed embodiments. Examples of deposition apparatus include various systems, such as ALTUS® or ALTUS® Max available from Lam Research Corp., Fremont, Calif., or various other commercially available processing systems. In some embodiments, atomic layer deposition (ALD) may be performed in a first station that is one of two, five, or even more deposition stations positioned within a single deposition chamber. Thus, for example, diborane (B2H6) and tungsten hexafluoride (WF6) may be introduced in alternating pulses to the surface of the semiconductor substrate in the first station using individual gas delivery systems that create air localized at the substrate surface. Another station may be used for tungsten bulk layer deposition. Another station may be used to deposit a cap layer by CVD. Two or more stations may be used to deposit tungsten in a parallel process. Alternatively, the wafer may be indexed to perform operations sequentially across two or more stations.

[0071] FIG. 6 is a schematic diagram of a processing system suitable for performing deposition processing according to embodiments. System 600 includes a transfer module 603. Transfer module 603 provides a clean, pressurized environment that minimizes the risk of contaminating the substrate being processed when moving the substrate between various reactor modules. Mounted on transfer module 603 is a multi-station reactor 609 capable of performing ALD and CVD according to various embodiments. Multi-station reactor 609 may include a number of stations 611, 613, 615, and 617 that may sequentially perform operations according to disclosed embodiments. For example, multi-station reactor 609 may be configured such that station 611 performs a tungsten nucleation layer deposition using a chlorine-containing tungsten precursor or a fluorine-containing precursor, and station 613 performs an ALD tungsten deposition operation according to various embodiments. In some embodiments, station 615 may also form an ALD tungsten deposition operation, and station 617 may perform a CVD operation.

[0072] The station may include a heated pedestal or substrate support, one or more gas inlets or showerheads, or a distribution plate. An example of a deposition station 700 including a substrate support 702 and a showerhead 703 is depicted in Figure 7. A heater may be provided in the pedestal portion 701.

[0073] Returning to FIG. 6, also mounted on the transfer module 503 may be one or more single or multi-station modules 607 capable of performing plasma pre-clean or chemical (non-plasma) pre-clean, other deposition operations, or etching operations. Additionally, the modules may be used for various procedures, such as to prepare substrates for deposition processing. The system 600 also includes one or more wafer source modules 601 that store wafers before or after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 619 may initially move the wafer from the source module 601 to the load lock 621. Wafer transfer equipment (typically a robot arm unit) in the transfer module 603 moves the wafer from the load lock 621 to and between modules mounted on the transfer module 603.

[0074] In various embodiments, a system controller 629 is used to control the process conditions during deposition. The controller 629 typically includes 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, etc.

[0075] The controller 629 may control all of the deposition equipment activities. The system controller 629 executes system control software that includes sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. In some embodiments, other computer programs stored in memory elements associated with the controller 629 may be used.

[0076] Typically, there is a user interface associated with the controller 629. The user interface may include a display screen, a graphical software representation of the equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0077] The system control logic may be configured in any suitable manner. In general, logic may be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry may be hard-coded or provided as software. Instructions may be provided by "programming." Such programming is understood to include any form of logic, including logic hard-coded into digital signal processors, application specific integrated circuits, and other elements that implement specific algorithms 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.

[0078] Computer program code for controlling the germanium-containing reducing agent pulses, hydrogen flow, and tungsten-containing precursor pulses, as well as other operations in the process sequence, can be written in any conventional computer readable programming language, such as assembly language, C, C++, Pascal, Fortran, etc. The processor executes compiled object code or scripts to perform the tasks identified in the program. Also, as shown, the program code may be hard coded.

[0079] The controller parameters relate to process conditions, such as process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature, etc. These parameters are provided to the user in the form of a recipe and may be entered using a user interface.

[0080] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 629. Signals for controlling the process are output on analog and digital output connections of the deposition apparatus 600.

[0081] The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be written to control the operation of chamber components necessary to perform deposition processes according to disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0082] In some implementations, the controller 629 is part of a system that may be part of the examples described above. Such a system may include semiconductor processing equipment including one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedals, gas flow systems, etc.). These systems may be integrated with electronics to control their operation before, during, and after processing of a semiconductor wafer or semiconductor substrate. The electronics may be referred to as a "controller" that may control various components or subdivisions of one or more systems. Depending on the processing requirements and / or type of system, the controller 629 may be programmed to control any of the processes disclosed herein, including delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow settings, fluid delivery settings, position and motion settings, wafer transfer into and out of tools and other transfer tools, and / or load locks connected to or interfaced with specific systems.

[0083] Broadly speaking, a controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute the program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing specific operations on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon oxides, surfaces, circuits, and / or dies of a wafer.

[0084] The controller 629 may be part of or coupled to a computer that is integrated with, coupled to, or otherwise networked to the system, or a combination thereof, in some implementations. For example, the controller 629 may be in the "cloud" or may be all or part of a host computer system in a semiconductor fab, thereby enabling remote access of wafer processing. The computer may enable remote access to the system to monitor the current progress of a fabrication operation, examine the history of past fabrication operations, examine trends or performance indicators from multiple fabrication operations, modify parameters of a current process, set up processing steps following a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows for entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by including one or more separate controllers networked together that work toward a common purpose, such as the process and control described herein. One example of a distributed controller for such purposes is one or more integrated circuits on the chamber that are in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control the process on the chamber.

[0085] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin and rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a CVD chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0086] As noted above, depending on the processing step or steps to be performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, nearby tools, adjacent tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to and from tool locations and / or load ports within the semiconductor manufacturing factory.

[0087] The controller 629 may include a variety of programs. A substrate positioning program may include program code for controlling chamber components used to load a substrate onto a pedestal or chuck and control spacing between the substrate and other parts of the chamber, such as gas inlets and / or targets. A process gas control program may include code for controlling gas composition, flow rates, pulse times, and optionally code for flowing gas into the chamber prior to deposition to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber, for example, by adjusting a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating unit used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas, such as helium, to the wafer chuck.

[0088] Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as pressure gauges, and thermocouples located in the pedestal or chuck. Data obtained from these sensors may be used to maintain desired process conditions using appropriately programmed feedback and control algorithms.

[0089] The apparatus may include a gas manifold system that provides line charges to various gas distribution lines as shown diagrammatically in FIG. 8. Manifold 804 has an input 802 from a source of tungsten-containing precursor gas (not shown), manifold 811 has an input 809 from a source of hydrogen or other reducing gas (not shown), and manifold 821 has an input 819 from a source of inert purge gas (not shown). Manifolds 804, 811, and 821 provide tungsten-containing precursor gas, reducing gas, and purge gas to the deposition chamber through valved distribution lines 805, 813, and 825, respectively. Various valves are opened and closed to provide the line charges, i.e., to pressurize the distribution lines. For example, to pressurize distribution line 805, valve 806, which applies a vacuum, is closed and valve 808 is closed. After an appropriate time, valve 808 is opened and tungsten-containing precursor gas is delivered to the chamber. Filling the tungsten precursor to high pressure (e.g., up to 400 Torr) during ALD deposition of the bulk layer can improve resistivity in some embodiments. After a suitable time to deliver the gas, valve 808 is closed. The chamber can then be purged and evacuated by opening vacuum valve 806.

[0090] A similar process is used to deliver reducing and purge gases. To introduce reducing gas, for example, fill distribution line 813 by closing valve 815 and closing valve 817 which applies a vacuum. Opening valve 815 allows the reducing gas to be delivered to the chamber. Similarly, to introduce purge gas, fill distribution line 825 by closing valve 827 and closing valve 823 which applies a vacuum. Opening valve 827 allows the delivery of argon gas or other inert purge gas to the chamber. The amount and timing of the initial delivery of gas will vary depending on the time it takes to allow the lines to fill.

[0091] 8 also shows a vacuum pump that can purge the system by opening valves 806, 817, and 823, respectively. The supply of gases through the various distribution lines is controlled by a controller, such as a mass flow controller controlled by a microprocessor, digital signal processor, or the like, programmed with flow rates, duration of flow, and sequencing of operations.

[0092] It should be noted that the above processes may require precise timing of valves and mass flow controllers (MFCs) to deliver pulses of reagents to the semiconductor substrate during deposition. One way to enable this is to deliver valve and MFC commands to an embedded digital input-output controller (IOC) in a separate information packet that contains instructions for all of the time-critical commands for all or part of the deposition sequence. Lam Research's ALTUS system provides at least one IOC sequence. The IOCs can be physically located at various points in the equipment, for example, inside the process modules or on a standalone power rack that is located a short distance away from the process modules. There may be multiple IOCs in each module (e.g., three per module). In terms of the actual instructions contained in the sequence, a single IOC sequence may contain all of the commands to the MFCs to control the valves and set the flows (for all carrier and reactant gases). This ensures that the timing of all the equipment is tightly controlled in absolute terms and relative to each other. There are typically multiple IOC sequences running at any given time. This allows, for example, ALD to operate at stations 1 and 2, with all timing controlled for all hardware components required to deposit an ALD-W nucleation layer at stations 1 and 2. Other deposition stations in the same module may deposit tungsten bulk using the timing sequence described above while a second sequence is running simultaneously. The relative timing of the instruments controlling the delivery of reagents to stations 3 and 4 is important within that group of instruments, but the relative timing of the ALD processes at stations 1 and 2 can be offset from the relative timing of stations 3 and 4. The IOC translates the information in the packetized sequences and delivers digital or analog command signals directly to MFCs or to pneumatic solenoid banks that control valves.

[0093] A pulse of tungsten-containing gas may be generated as follows: First, the system diverts WF6 to the vacuum pump for a period of time during which the MFC or other flow control device is stable. In one example, this may be done for a period of between about 0.5 seconds and 5 seconds. The system then pressurizes the tungsten gas delivery manifold by closing both the diversion outlet 606 and the outlet 608 to the deposition chamber. This may be done for a period of between about 0.1 seconds and 5 seconds, for example, to create an initial burst of reagent when the outlet to the deposition chamber opens. In one example, this is accomplished by opening the outlet valve 808 for a period of between about 0.1 seconds and 10 seconds. The tungsten-containing gas is then purged from the deposition chamber using an appropriate purge gas. Flows of other reagents may be pulsed in a similar manner.

[0094] The foregoing describes implementing the disclosed embodiments in single or multi-chamber semiconductor processing tools. The apparatus and methods described herein may be used in association with lithographic patterning tools or patterning processes, for example to fabricate or manufacture semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, but not necessarily, such tools are used together in a common fabrication facility or such processes are performed together in a common fabrication facility. Lithographic patterning of films typically includes some or all of the following steps, each of which may include: (1) applying photoresist onto a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curing the photoresist using a hotplate or 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 selectively remove the resist and thereby pattern the resist using a tool such as a wet bench; (5) transferring the resist pattern into the underlying film or workpiece by using a dry etching tool or a plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper, with each step including several possible tools.

[0095] conclusion Although the foregoing embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be made 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. Thus, the present embodiments should be considered as illustrative and not restrictive, and the embodiments should not be limited to the details shown herein. The present invention can be realized, for example, in the following manner. Application example 1: 1. A method comprising: Providing a structure to be filled with a tungsten-containing material; Exposing the structure to a number of deposition cycles, each of which includes introducing nitrogen (N 2 ) and hydrogen (H 2 ) and a dose of a tungsten precursor; A method for providing the above. Application example 2: The method of Application Example 1, wherein the structure is a partially fabricated three-dimensional (3-D) NAND structure having sidewalls and a plurality of openings in the sidewalls, the plurality of openings leading to a plurality of features having a plurality of internal regions accessible by fluid through the openings. Application example 3: The method of application example 1, wherein the administration of the tungsten precursor comprises administering the N 2 The H that flows together with 2 wherein the dose is delivered at a pressure greater than that of the subject. Application example 4: The method of any one of application examples 1 to 3, wherein the dose of tungsten precursor is delivered at a pressure of at least 300 Torr. Application example 5: The method according to any one of application examples 1 to 3, wherein the dose of the tungsten precursor is delivered without the nitrogen. Application example 6: In the method according to any one of Application Examples 1 to 3, 2 N 2 The H that flows together with 2 N of said administration 2 +H 2 A method in which the volume of the total flow is between 10% and 30%. Example 7: In the method of Application Example 6, the substrate temperature is 2 The H that flows together with 2 wherein the temperature is below 350° C. during said administration. Application example 8: In the method according to any one of Application Examples 1 to 3, 2 N 2 +H 2 The substrate temperature is increased by more than 30% (by volume) of the total flow of N 2 The H that flows together with 2 wherein the temperature is at least 375° C. during said administering. Example 9: The method according to any one of Application Examples 1 to 3, wherein the tungsten precursor is tungsten hexafluoride. Example 10: The method according to any one of Application Examples 1 to 3, wherein the tungsten precursor is a chlorine-containing tungsten precursor. Example 11: 1. A method comprising: providing a structure having a gap to be filled with a tungsten-containing material; Exposing the structure to a number of deposition cycles, each of which may include a hydrogen (H 2 ) and a tungsten precursor to deposit a bulk tungsten film in the gap; forming a cap layer on the bulk tungsten film; A method for providing the above. Example 12: The method of application example 11, wherein the structure is a partially fabricated three-dimensional (3-D) NAND structure having sidewalls and multiple openings in the sidewalls that lead to the gaps that are filled with tungsten. Application example 13: The method of claim 12, further comprising depositing the cap layer on the sidewalls. Example 14: The method according to any one of Application Examples 11 to 13, wherein the cap layer is a tungsten oxide layer. Example 15: The method according to any one of Application Examples 11 to 13, wherein the cap layer is an amorphous tungsten layer. Application example 16: A method according to any one of Application Examples 11 to 13, comprising providing the structure in a multi-station deposition chamber, performing the multiple deposition cycles in one or more first stations of the multi-station deposition chamber, and forming the cap layer in one or more second stations of the multi-station deposition chamber. Example 17: 1. A method comprising: (a) depositing a tungsten nucleation layer in a feature on a substrate by alternating pulses of a tungsten precursor and a boron-containing reducing agent; (b) The tungsten precursor and hydrogen (H 2 depositing a tungsten template layer on the tungsten nucleation layer by alternating pulses of (c) after (b), increasing the substrate temperature by at least 50° C.; (d) After (c), the tungsten precursor and the hydrogen (H 2 depositing a bulk layer of tungsten by alternating pulses of A method for providing the above. Example 18: The method of claim 17, wherein the tungsten nucleation layer is deposited to a thickness of 30 Å or less. Example 19: An apparatus comprising: a processing chamber having one or more stations each configured to hold a substrate; Hydrogen (H 2 ) gas source, nitrogen (N 2 ) a gas supply, and one or more process gas inlets for coupling to a tungsten precursor gas supply; Nitrogen (N 2 ) and hydrogen (H 2 a controller for controlling operation within the apparatus comprising machine readable instructions for sequentially delivering a dose of the tungsten precursor to the processing chamber; An apparatus comprising:

Claims

1. 1. A method comprising: providing a structure having a gap to be filled with a tungsten-containing material; Exposing the structure to multiple deposition cycles, each of which may include a hydrogen (H 2 ) and a tungsten precursor to deposit a bulk tungsten film in the gap; forming a cap layer on the bulk tungsten film; Equipped with The method wherein the cap layer is a tungsten oxide layer.

2. 2. The method of claim 1, wherein the structure is a partially fabricated three-dimensional (3-D) NAND structure having sidewalls and a number of openings in the sidewalls that lead to the gaps that are filled with tungsten.

3. The method of claim 2 , further comprising depositing the cap layer on the sidewalls.

4. 4. The method of claim 1, further comprising providing the structure in a multi-station deposition chamber, performing the multiple deposition cycles in one or more first stations of the multi-station deposition chamber, and forming the cap layer in one or more second stations of the multi-station deposition chamber.

5. 1. A method comprising: (a) depositing a tungsten nucleation layer in a feature on a substrate by alternating pulses of a tungsten precursor and a boron-containing reducing agent; (b) reacting the tungsten precursor with hydrogen (H) at a substrate temperature between 250° C. and 350° C. 2 depositing a tungsten template layer on the tungsten nucleation layer by alternating pulses of (c) after (b), increasing the substrate temperature by at least 50° C.; (d) After (c), the tungsten precursor and the hydrogen (H 2 depositing a bulk layer of tungsten by alternating pulses of A method for providing the above.

6. 6. The method of claim 5, wherein the tungsten nucleation layer is deposited to a thickness of 30 Å or less.

7. 1. A method comprising: providing a partially fabricated three-dimensional (3-D) NAND structure having a central vertical structure with a plurality of openings on opposing sidewalls of the central vertical structure, the plurality of openings leading to a plurality of wordline features separated by a plurality of oxide layers, the plurality of wordline features being filled with a tungsten-containing material; Exposing the 3-D NAND structure to multiple deposition cycles, each deposition cycle containing hydrogen (H 2 exposing the 3-D NAND structure, comprising sequentially delivering a dose of a tungsten precursor and a dose of a tungsten precursor to deposit a bulk tungsten film in the wordline features; forming a tungsten-containing cap layer on opposing sidewalls of the central vertical structure, including on the filled wordline features and on the oxide layers.

8. 1. A method comprising: providing a structure having a gap to be filled with a tungsten-containing material; Exposing the structure to multiple deposition cycles, each of which may include a hydrogen (H 2 ) and a tungsten precursor to deposit a bulk tungsten film in the gap; forming a cap layer on the bulk tungsten film; Equipped with The method wherein the cap layer is an amorphous tungsten layer.

9. 10. The method of claim 8, wherein the structure is a partially fabricated three-dimensional (3-D) NAND structure having sidewalls and a number of openings in the sidewalls that lead to the gaps that are filled with tungsten.

10. The method of claim 9 , further comprising depositing the cap layer on the sidewalls.

11. 11. The method of any one of claims 8 to 10, comprising providing the structure in a multi-station deposition chamber, performing the multiple deposition cycles in one or more first stations of the multi-station deposition chamber, and forming the cap layer in one or more second stations of the multi-station deposition chamber.

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