Atomic layer deposition on 3D NAND structures

Abstract

Methods and apparatus that provide tungsten deposition with low roughness are described. In some embodiments, the method includes co-flowing nitrogen with hydrogen during an atomic layer deposition process of tungsten deposition using hydrogen as a reducing agent. In some embodiments, the method includes depositing a capping layer, such as a tungsten oxide or amorphous tungsten layer, on sidewall surfaces of the 3D NAND structure. The disclosed embodiments have a wide range of applications, including deposition of tungsten into 3D NAND structures.

Description

This application is a divisional application of the invention patent application with application number 201980092041.9, application date December 13, 2019, applicant is Rum Research Company, and invention name is "Atomic layer deposition on 3D NAND structure". Incorporated by Reference

[0001] The PCT application form is filed concurrently with this specification as a part of this application. Each application to which this application claims the benefit of or priority as identified in the concurrently filed PCT application form is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] The deposition of tungsten-containing materials is an integral part of many semiconductor manufacturing processes. These materials can be used for horizontal interconnects, vias between adjacent metal layers, and contacts between metal layers and devices. However, as devices shrink and the industry uses more complex patterning schemes, the deposition of 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 here is for the purpose of generally presenting the context of the present disclosure. No admission is made, either explicitly or implicitly, that the work of the presently designated inventors is prior art to the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed. Summary of the Invention

[0004] One aspect of the present disclosure relates to a method comprising providing a structure to be filled with a tungsten-containing material; and exposing the structure to a plurality of deposition cycles, wherein each deposition cycle comprises sequentially delivering a dose of hydrogen (H2) co-flowed with nitrogen (N2) and a dose 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 comprising sidewalls and a plurality of openings in the sidewalls leading to a plurality of features having a plurality of interior regions fluidly accessible through the openings.

[0006] In some embodiments, the dose of the tungsten precursor is delivered at a pressure of at least 300 Torr.

[0007] In some embodiments, the dose of the tungsten precursor is delivered in the absence of nitrogen.

[0008] In some embodiments, N2 is between 10-30% (volume) of the total N2+H2 flow.

[0009] In some embodiments, the substrate temperature does not exceed 350° C. during the dose of H 2 co-flowing with N 2 .

[0010] In some embodiments, during the dose of H2 co-flowing with N2, N2 is greater than 30% (volume) of the total N2+H2 flow rate and the substrate temperature is at least 375° C. 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 co-flowing with N2.

[0011] The present disclosure relates to a method comprising: providing a structure having a gap to be filled with a tungsten-containing material; exposing the structure to a plurality of deposition cycles, wherein each deposition cycle comprises sequentially delivering a dose of hydrogen (H2) and a dose of a tungsten precursor to deposit a bulk tungsten film in the gap; and forming a capping layer on the bulk tungsten film.

[0012] In some embodiments, the structure is a partially fabricated three-dimensional (3-D) NAND structure that includes sidewalls and a plurality of openings in the sidewalls leading to the gap to be filled with tungsten.

[0013] In some embodiments, the capping layer is a tungsten oxide layer.

[0014] In some embodiments, the capping layer is an amorphous tungsten layer.

[0015] In some embodiments, the structure is provided to a multi-station deposition chamber, and wherein the plurality of deposition cycles are performed in one or more first stations of the multi-station deposition chamber, and the cap layer is formed in one or more second stations of the multi-station deposition chamber. In some embodiments, the cap layer is deposited on the sidewalls.

[0016] Another aspect of the present disclosure relates to 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) depositing a tungsten template layer on the tungsten nucleation layer by alternating pulses of the 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.

[0017] In some embodiments, the tungsten nucleation layer is deposited to a thickness of no more than 30 angstroms.

[0018] Yet another aspect of the present disclosure relates to an apparatus comprising: a processing chamber having one or more stations, each station configured to hold a substrate; one or more process gas inlets for coupling to a hydrogen (H2) gas source, a nitrogen (N2) gas source, and a tungsten precursor gas source; and a controller for controlling operations in the apparatus, comprising machine-readable instructions for sequentially delivering a dose of hydrogen (H2) co-flowed with nitrogen (N2) and a dose of a tungsten precursor to the processing chamber.

[0019] These and other aspects are described in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A Presented is a cross-sectional side view of a 3-D NAND structure that may be filled with tungsten according to embodiments described herein.

[0021] Figure 1B Presented Figure 1A A cross-sectional top view of a -D NAND.

[0022] Figure 2A and 2B is a process flow diagram describing the operation of a method according to certain disclosed embodiments.

[0023] Figure 2C is a timing diagram illustrating example cycles in a method for depositing a film according to certain disclosed embodiments.

[0024] Figure 3 A cross-sectional side view of a filled wordline feature of a 3D-NAND structure is presented.

[0025] Figure 4 is a timing diagram illustrating exemplary cycles in a method for depositing a film according to certain disclosed embodiments.

[0026] Figures 5A-5D is a process flow diagram describing the operation of a method according to certain disclosed embodiments.

[0027] Figure 6 is a schematic diagram of an exemplary processing tool for performing certain disclosed embodiments.

[0028] Figure 7 is a schematic diagram of an exemplary station for performing certain disclosed embodiments.

[0029] Figure 8 is a schematic diagram illustrating basic features of a manifold system that may be used in accordance with certain embodiments. DETAILED DESCRIPTION

[0030] In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments presented. The disclosed embodiments can be practiced without some or all of these specific details. In other instances, well-known processing operations are not described in detail to avoid unnecessarily obscuring the disclosed embodiments. Although the disclosed embodiments will be described in conjunction with specific embodiments, it should be understood that they are not intended to limit the disclosed embodiments.

[0031] Tungsten (W) filling of features is frequently used in semiconductor device manufacturing to form electrical contacts. In conventional methods for depositing tungsten films, a nucleated tungsten layer is first deposited into the via or contact. Typically, the nucleation layer is a thin, conformal layer used to facilitate the subsequent formation of the bulk material thereon. The tungsten nucleation layer can be deposited to conformally coat the sidewalls and bottom of the feature. Conformity with the underlying feature bottom and sidewalls is crucial to support high-quality deposition. The nucleation layer is typically deposited using atomic layer deposition (ALD) or pulsed nucleation layer (PNL) methods.

[0032] In ALD or PNL techniques, pulses of reactants are injected sequentially and are typically purged from the reaction chamber by pulses of a sweep gas between reactants. The first reactant may be adsorbed onto the substrate, which is available to react with the next reactant. The process is repeated in a cyclical manner until the 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 for vapor phase or surface reactions. PNL and ALD processes are distinct from CVD processes and vice versa.

[0033] After the tungsten nucleation layer is deposited, 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 the tungsten nucleation layer. Bulk tungsten as used herein refers to tungsten that is used to fill most or all of a feature (e.g., at least about 50% of a feature). Unlike the nucleation layer, which is a thin conformal film that is used to facilitate the subsequent formation of a bulk material thereon, bulk tungsten is used to carry current. It is characterized by a larger grain size and lower resistivity than the nucleation film. In various embodiments, bulk tungsten may be deposited to at least The thickness of tungsten.

[0034] As devices scale to smaller technology nodes and use more complex patterned structures, tungsten fill presents various challenges. One challenge is conformal deposition within these structures to distribute the material evenly throughout the structure. The distribution of material within a feature or structure can be characterized by its step coverage. For the purposes of this specification, "step coverage" is defined as the ratio of two thicknesses. For example, step coverage can be the thickness of the material inside the feature divided by the thickness of the material near the opening. For the purposes of this document, the term "inside a feature" refers to the middle portion of a feature located near the midpoint of the feature along the feature axis, for example, between approximately 25% and 75% of the feature's depth, or, in certain embodiments, between approximately 40% and 60% of the feature's depth, or at the end of a feature located between approximately 75% and 95% of the feature's depth, measured from the opening. The terms "near the feature's opening" or "near the feature opening" mean that the top of the feature is within 25%, or more specifically, within 10%, of the edge of the opening or other typical element representing the edge of the opening. For example, by filling a feature wider near the middle or bottom of the feature than at the feature opening, step coverage exceeding 100% can be achieved.

[0035] Another challenge is reducing the fluorine concentration or content in the deposited tungsten film. Smaller features in a tungsten film with the same fluorine concentration as larger features have a more significant impact on device performance than larger features. For example, the smaller the features, the thinner the deposited film. As a result, the fluorine in the deposited tungsten film is more likely to diffuse through the thinner film, potentially leading to device failure. Sidewall roughness is also a challenge for structures such as 3D NAND structures.

[0036] The methods and apparatus provided herein may have one or more of the following advantages. In some implementations, they provide tungsten deposition with reduced roughness. This can be achieved by providing smoother growth without intermediate etching operations. Low-fluorine tungsten can be deposited. Furthermore, the methods may provide good step coverage. The disclosed embodiments have a wide range of applications, including depositing tungsten into 3D NAND structures.

[0037] The disclosed embodiments can be used to deposit tungsten with reduced tungsten content. This can be achieved by providing smoother growth without intermediate etching operations. Low-fluorine tungsten can be deposited. Furthermore, the methods can provide good step coverage. The disclosed embodiments have a wide range of applications, including deposition of tungsten into 3D NAND structures.

[0038] The methods described herein are performed on a substrate that can be contained in a chamber. The substrate can be a silicon or other semiconductor wafer, such as a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material (e.g., dielectric, conductive, or semiconductive material) deposited thereon. The methods are not limited to semiconductor substrates and can be performed to fill any feature with a metal (e.g., tungsten).

[0039] Figure 1A A cross-sectional side view of a 3-D NAND (also referred to as a vertical NAND or VNAND) structure 110 (formed on a semiconductor substrate 103) is presented having a VNAND stack (left 125 and right 126), a central vertical structure 130, and a plurality of stacked horizontal features 120 having openings 122 on opposing sidewalls 140 of the central vertical structure 130. Note Figure 1A Two stacks 125 and 126 of the illustrated 3-DNAND structure 110 are shown, which together form a trench-like central vertical structure 130. However, in some embodiments, there may be more than two stacks arranged in sequence and spaced parallel to each other, with the gap between each pair of adjacent stacks forming the central vertical structure 130, as shown in FIG. Figure 1A As clearly stated in Figure 1A In the example of FIG, horizontal feature 120 is a 3-D memory word line feature that is fluidically accessible from central vertical structure 130 through opening 122. Although not explicitly indicated in the figure, the presence of Figure 1A The horizontal features 120 in both the 3-D NAND stacks 125 and 126 shown in FIG. 1 (i.e., the left 3-D NAND stack 125 and the right 3-D NAND stack 126) are also accessible from the other sides of the stack (the leftmost and rightmost sides, respectively) through similar vertical structures formed by additional 3-D NAND stacks (the leftmost and rightmost sides, but not shown). In other words, each 3-D NAND stack 125, 126 includes stacked word line features that are fluidically accessible from both sides of the 3-D NAND stack through the central vertical structure 130.

[0040] The wordline features in a 3-D NAND stack are typically formed by depositing alternating stacks of silicon oxide and silicon nitride layers, and then selectively removing the nitride layers, leaving behind stacked oxide layers 142 with gaps between the oxide layers 142. These gaps are the wordline features. Any number of wordlines can be stacked vertically in such a 3-D NAND structure, as long as there is a technique available to form them and a technique available to successfully achieve (substantially) gap-free fill of the vertical features. Thus, for example, a VNAND stack can 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. (listed ranges are understood to include the recited endpoints).

[0041] Figure 1B Presentation and Figure 1A FIG. 1 is a cross-sectional top view of the same 3-D NAND structure 110 shown in side view in FIG. 1 , wherein the cross section is taken through horizontal portion 160 . Figure 1A Indicated by the horizontal dashed line in . Figure 1B The cross-sectional view illustrates several rows of columns 155, which are Figure 1A 10 as extending vertically from the bottom of the semiconductor substrate 103 to the top of the 3-D NAND stack 110. In some embodiments, these pillars 155 are made of polysilicon material and are structurally and functionally important to the 3-D NAND structure 110. In some embodiments, such polysilicon pillars can serve as gate electrodes for stacked memory cells formed within the pillars. Figure 1B The top view illustrates that the pillar 155 is formed in the opening 122 to the constriction of the wordline feature 120 - that is, the fluid accessibility of the wordline feature 120 from the central vertical structure 130 through the opening 122 (eg, Figure 1B ) is suppressed by pillars 155. In some embodiments, the horizontal gap between adjacent polysilicon pillars has a size between about 1 and 20 nm. This reduction in fluid accessibility increases the difficulty of uniformly filling wordline features 120 with tungsten material.

[0042] Figures 2A-2C Methods that can be performed to fill 3D NAND structures with low fluorine and low resistivity tungsten are described. Figure 2A ,implement Figure 2A The tungsten nucleation layer is deposited by ALD using operations 202-210. 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 can 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 about 3 Torr.

[0043] The deposition process is performed at a lower pressure than the subsequent bulk deposition in operation 280. For example, operations 202-210 may be performed at a lower pressure than about 10 Torr. In some examples, operations 202-210 may be performed at a lower pressure than about 10 Torr.

[0044] The process is performed at a pressure of about 10 Torr or about 3 Torr.

[0045] In some implementations, performing operations 202 - 210 at low pressure reduces the fluorine concentration in the deposited tungsten film due to the lower partial pressure of the fluorine-containing precursor in the chamber when depositing the film, such that less fluorine is incorporated into the film.

[0046] In operation 202, the substrate is exposed to a tungsten-containing precursor, such as WF6. For the purposes of this description, although WF6 is used as an example of a tungsten-containing precursor, it should be understood that other tungsten-containing precursors may be suitable for performing the disclosed embodiments. For example, a metal-containing organic tungsten precursor may be used. Organometallic precursors and fluorine-free precursors such as MDNOW (methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW (ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten) may also be used. Tungsten chloride (WCl x ) and tungsten hexacarbonyl W(CO) 6 tungsten-containing precursors may include combinations of these compounds. In some embodiments, a carrier gas (e.g., nitrogen (N 2 ), argon (Ar), helium (He), or other inert gases) may flow during operation 202 .

[0047] Operation 202 can be performed for any suitable duration and at any suitable temperature. In some examples, operation 202 can be performed for a duration between about 0.25 seconds and about 30 seconds, about 0.25 seconds and about 5 seconds, or about 0.5 seconds and about 3 seconds. This operation can, in some embodiments, be performed for a duration sufficient to saturate the active sites on the substrate surface.

[0048] The chamber is optionally purged to remove excess WF6 that is not adsorbed onto the substrate surface in operation 204. The purge can be performed by flowing an inert gas at a fixed pressure, thereby reducing the chamber pressure and re-pressurizing the chamber before starting another gas exposure.

[0049] In operation 406, the substrate is exposed to a reducing agent to deposit a tungsten nucleation layer. The reducing agent can be a borane, a silane, or a germane. Exemplary boranes include borane (BH3), diborane (B2H6), triborane, alkylboranes, aminoboranes, carboranes, and halogenated boranes. Exemplary silanes include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), alkylsilanes, aminosilanes, carbosilanes, and halogenated silanes. Germanes include Ge n H n+4 、Gen H n+6 、Ge n H n+8 and Ge n H m , wherein n is an integer from 1 to 10, and n is an integer different from m. Other germanes, such as alkylgermanes, aminogermanes, carbogermanes, and halogenated germanes, may also be used. Generally, halogenated germanes may not have a significant reduction potential, but there may be process conditions and tungsten-containing precursors suitable for forming films using halogenated germanes.

[0050] Operation 206 can be performed for any suitable duration. In some examples, exemplary durations include between about 0.25 seconds and about 30 seconds, between about 0.25 seconds and about 5 seconds, or between about 0.5 seconds and about 3 seconds. In some embodiments, this operation can be sufficient to react with the adsorbed layer of WF6 on the substrate surface. Operation 206 can be performed for durations outside these example ranges. In some embodiments, a carrier gas such as argon (Ar), helium (He), or nitrogen (N2) can be used.

[0051] After operation 208, there may be an optional purge step to remove excess reducing agent still in the gas phase that does not react with the WF6 on the surface of the feature. The purge may be performed by flowing an inert gas at a fixed pressure, thereby reducing the pressure of the chamber and re-pressurizing the chamber before initiating another gas exposure.

[0052] In operation 210, it is determined whether the tungsten nucleation layer has been deposited to a sufficient 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 implementations, the order of operations 202 and 206 may be reversed, such that the reducing agent is introduced first.

[0053] After the tungsten nucleation layer is deposited to a sufficient thickness, bulk tungsten is deposited in operation 280 as described below. In various embodiments, operation 280 can be performed at a pressure greater than the pressure during operations 202-210. For example, operation 280 can be performed at a pressure greater than or equal to about 10 Torr, such as about 10 Torr, or about 40 Torr. In some embodiments, the pressure during deposition of the nucleation layer and bulk layer can be about 5-20 Torr, or 10 Torr.

[0054] Figure 2B A process flow diagram of the operations that may be performed during operation 280 is provided. Note that the Figure 2A Execute in case of operation Figure 2B operation. Figure 2CA timing diagram describing an exemplary cycle of ALD in process 200 is provided.

[0055] exist Figure 2B In operation 282, the substrate is exposed to a reducing agent such as H2. This operation may be referred to as "pulsing" or "dosing," which may be used interchangeably herein. H2 is pulsed without the flow of another reactant. In some embodiments, a carrier gas may flow. The carrier gas may be a Figure 2A Any of those carrier gases described in operation 204 of FIG. Operation 282 can be performed for any suitable duration. In some examples, exemplary durations include between about 0.25 seconds and about 30 seconds, between about 0.25 seconds and about 5 seconds, or between about 0.5 seconds and about 3 seconds.

[0056] Figure 2C H2 dosing 220A in deposition cycle 211A is shown, which may correspond to Figure 2B Operation 282. During H2 dosing 220A, the carrier gas flows, the reducing agent is pulsed, and the WF6 flow is turned off.

[0057] Return to Figure 2B At operation 284, the chamber is purged. This purging operation can remove excess H2 that remains in the gas phase. Purging is performed by flowing an inert gas at a fixed pressure, thereby reducing the chamber pressure and re-pressurizing the chamber before initiating another gas exposure. The chamber can be purged for any suitable duration, for example, for a duration between about 0.1 seconds and about 3 seconds. Figure 2B Operation 284 may correspond to Figure 2C The cleaning phase 240A. Figure 2C As shown, during the sweep phase 240A, the carrier gas is flowing, but the H2 flow and the WF6 flow are turned off.

[0058] return Figure 2B In operation 286, the substrate is exposed to a tungsten-containing precursor (e.g., WF6) to form a sub-monolayer or monolayer of film on the substrate. In various embodiments, WF6 flows into the chamber during this operation for a duration between about 0.1 seconds to about 3 seconds or about 0.5 seconds. In some embodiments, WF6 can be transferred to fill the gas line and the line changed before dosing. In some embodiments, WF6 flows into the chamber but does not completely react with all H2 molecules on the substrate surface. Operation 286 may correspond to Figure 2C The WF6 in the tank is dosed at 260A. Figure 2C As shown, during WF6 dosing 260A, the carrier gas is flowing, the H2 flow is off, and the WF6 flow is on.

[0059] exist Figure 2BIn operation 288, the chamber is purged to remove the byproducts of the reaction and WF6 in the gas phase from the chamber. In some embodiments, the purge duration is between about 0.1 seconds and about 2 seconds, and the low adsorption rate of WF6 to the tungsten surface may prevent all WF6 from being removed from the substrate surface. In some embodiments, the purge duration is between about 0.1 seconds and about 15 seconds, for example, about 7 seconds. For example, to manufacture a 3D NAND structure, the chamber may be purged for about 7 seconds during operation 288. The purge duration depends on the substrate and stress.

[0060] Figure 2B Operation 288 may correspond to Figure 2C The cleaning phase 270A. Figure 2C As shown, sweep phase 270A concludes deposition cycle 211A. In some embodiments, operations 286 and 282 can be reversed such that operation 286 is performed before operation 282. In some embodiments, operation 282 can be performed before operation 286.

[0061] exist Figure 2B In operation 290, it is determined whether the bulk tungsten has been deposited to a sufficient thickness. If not, operations 282-288 are repeated until the desired thickness is deposited. In some embodiments, operations 282-288 are repeated until the feature is filled. Figure 2C In the process, it was determined that the bulk tungsten was not deposited to a sufficient thickness, so the deposition cycle 211B was repeated. Figure 2B Operations 282-288 result in the execution of H2 dosing 220B, followed by a sweep phase 240B. WF6 dosing 260B is executed, followed by another sweep phase 270B.

[0062] The disclosed embodiments may have various applications in tungsten deposition processes. For example, in some embodiments, a feature may be filled by depositing a tungsten nucleation layer via an ALD cycle using alternating pulses of a reducing agent (e.g., borane, silane, or germane) and WF6, followed by bulk tungsten deposition via an ALD cycle using alternating pulses of H2 and WF6. In some embodiments, as described above with reference to Figure 2B and 2C The bulk deposition performed directly on the underlying feature or layer can omit the tungsten nucleation layer.Tungsten films deposited using the disclosed embodiments have low fluorine concentration, low stress, good step coverage, and low resistivity.

[0063] In some aspects, the methods described herein provide smooth films with low roughness. For example, in a 3D NAND structure, the sidewalls 140 of the 3D NAND stacks 125, 126 will have tungsten at the opening of each tungsten wordline deposited at each horizontal feature 120. Figure 3346. The tungsten at 346 lines the sidewalls 340 of the stack comprising the wordline 320 and the oxide layer 342 and is etched back in subsequent processing. However, sidewall roughness can lead to uneven profiles after etch back and can ultimately cause the etch chemistry to diffuse into the wordline and device failure.

[0064] While CVD techniques can produce smooth sidewall coverage, they may lack step coverage and conformality within features. This paper provides an ALD method that results in low roughness and can be used with the above references. Figures 2A-2C The ALD method described herein can reduce surface diffusion of W adatoms, which can cause faceting and roughness outside the gap (e.g., in the center trench of a 3D-NAND).

[0065] In some embodiments, the method comprises Figure 2B In operation 282, nitrogen (N2) is co-flowed with the reducing agent. Figure 4 A timing diagram is provided to illustrate an example cycle of ALD in process 400. The timing diagram is similar to Figure 2B In the timing diagram, N2 is added to the co-flow during H dosing. In particular, Figure 4 H2+N2 dosing 420A is shown in deposition cycle 411A, which may correspond to Figure 2B Operation 282. During H2 dosing 420A, the carrier gas flows, H2 and N2 are pulsed, and the WF6 flow is turned off. Deposition cycle 411A also includes WF6 dosing 460A and as described above with reference to Figure 2C These operations are repeated in subsequent deposition cycles, as shown in 420B, 440B, 460B, and 470B. Compared to the sidewall roughness without nitrogen flow during H2 operation, the sidewall roughness of the substrate is significantly improved with the use of Figure 4 The timing sequence shown in Figure 3 significantly reduces sidewall roughness. In particular, the sidewall roughness was found to be reduced by approximately half. This is likely due to the addition of N2 to the surface, which inhibits the diffusion of W adatoms (adatoms) and suppresses tungsten growth at feature corners. Notably, flowing N2 during the reducing agent dosing was found to reduce roughness more than flowing it during the tungsten precursor pulse.

[0066] According to various embodiments, N2 can represent approximately 10-30% (vol.) of the total N2+H2 flow rate. Higher N2 flow rates can be used, which can result in further reductions in roughness but increase film resistivity and / or stress. This increase in stress can be prevented or avoided by using relatively high temperatures, such as 375°C or higher, for example, 400°C.

[0067] In some embodiments, Figure 2BIn the ALD process, the roughness is improved by using a chamber pressure of at least 20 Torr or 25 Torr. Figure 2C and Figure 4 The deposition cycles 200 and 400 shown in FIG can be performed at approximately 25 Torr. This shows an improvement of 10 Torr, likely due to a reduction in the diffusion length of W adatoms. The chamber pressure can be between 20 Torr and 40 Torr to reduce roughness. At pressures above 40 Torr, step coverage may be affected because the process becomes too CVD-like and cleaning may be difficult.

[0068] In some embodiments, the tungsten precursor is delivered at a high dosing pressure during operation 286. As described below, the gas lines can be filled to deliver each reactant. Delivering the tungsten precursor at a high fill pressure, such as at least 300 Torr or about 400 Torr, results in lower roughness. This may be due to higher adsorption on the surface, which limits the diffusion of adatoms. In some embodiments, the tungsten precursor is delivered at a pressure between 400 Torr and 700 Torr.

[0069] Table 1 below shows the roughness reduction achieved under different process conditions within the scope of the present disclosure.Tungsten was deposited in a 3-D NAND structure to fill wordline features and the sidewall roughness was measured.

[0070] At high temperatures, sidewall roughness can be reduced by co-flowing N2 with WF6. For example, at temperatures above 400°C, co-flowing N2 with WF6 (or other precursors) has been shown to reduce roughness from 7.4nm to 3.5nm. N2 can account for 10%-90% vol. of the total N2+WF6 flow, where higher N2 leads to lower roughness without degrading film performance. At lower temperatures (e.g., 300°C), roughness may not improve. This is in contrast to the other methods mentioned above, where roughness can be reduced at low temperatures (e.g., 300°C).

[0071] Figure 5A is a process flow diagram illustrating another method of filling a structure having a gap with tungsten. In some embodiments, the structure is as follows Figure 1A The method begins at operation 502, where a tungsten nucleation layer is deposited to conformally line the structure with tungsten. Operation 502 may be as described above with reference to Figure 2A In some embodiments, a silicon-containing and / or boron-containing reducing agent is used during the deposition of the tungsten nucleation layer. In some embodiments, operation 502 can be omitted, as described above. Next, a bulk tungsten layer is deposited by ALD in operation 504 to fill the gaps in the structure. Operation 504 can refer to Figure 2AOperations 282-290 and / or Figure 2C and Figure 4 The timing diagrams 200 and 400 in FIG. 1 are performed as described above. However, rather than allowing deposition to continue outside of the feature (e.g., Figure 4 346 in the example of ), but instead stops deposition at operation 506. At this point, the interior of the wordline feature can be complete or filled. A cap layer is then formed on the bulk tungsten in operation 508. The cap layer is a relatively thin layer (thinner than the bulk tungsten layer) and can be deposited by CVD or ALD in some embodiments. An exemplary thickness range is 100-200 angstroms. Examples of cap layers include amorphous tungsten and tungsten oxide layers. The cap layer can be formed only on the exterior of the wordline feature.

[0072] In some embodiments, block 508 involves CVD deposition of a capping layer on the sidewalls of the 3D-NAND structure. CVD deposition on the 3D-NAND structure improves the smoothness of the sidewalls. This is because its higher deposition rate allows for less time for W adatoms to diffuse onto the surface. Therefore, transitioning from block 506 to block 508 can involve transitioning from alternating pulses of the tungsten precursor and (hydrogen or other reducing agent) into the deposition chamber to simultaneously introducing the tungsten precursor and reducing agent into the deposition chamber.

[0073] In some embodiments, block 508 involves forming a tungsten oxide capping layer on the sidewalls of the 3D-NAND structure. For example, this may involve forming a tungsten oxide capping layer according to Figure 2C A relatively thin tungsten ALD layer is deposited in a sequential order of 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 709, 809, 810, 820, 830, 840, 850, 860, 870, 880, 890, 909, 910, 920, 930, 940, 950, 960, 970, 980, 990, 10 ...

[0074] In some embodiments, block 508 may involve performing the following steps as described above with respect to Figure 2A Deposition of an ALD tungsten layer formed by the described method. While the cap layer is not a "nucleation" layer in the sense that there is typically no bulk deposited on top of it, it can be smoother than the bulk layer. An ALD tungsten layer deposited using a silane or boron reducing agent and a tungsten precursor can be an amorphous tungsten layer.

[0075] Table 2 below shows the roughness reduction achieved for different capping layers within the scope of the present disclosure.Tungsten was deposited in a 3-D NAND structure to fill wordline features and the sidewall roughness was measured.

[0076] It should be noted that a higher resistivity of the capping layer can be tolerated since the capping layer will be removed during a subsequent etching operation.

[0077] Figure 5Bis a process flow diagram illustrating another method of filling a structure having a gap with tungsten. Figure 5B In the operation 602 and 604 can be as described above with respect to Figure 5A At 556, crystal growth of the ALD layer is stopped. This may involve stopping the ALD deposition and performing a process to interrupt grain growth. In some embodiments, block 558 may involve performing the process described above with respect to Figure 2A The nitrogen (N2) soaking or tungsten nucleation layer deposition is then carried out as described above. Figure 2C and 4 The bulk layer deposition process is performed, however, grain growth is restarted, thereby reducing roughness. In some embodiments, bulk layer deposition conditions may be changed from operation 504 to operation 558. For example, operation 504 may involve Figure 2C The timing diagram described in , without nitrogen co-flow, as Figure 4 Nitrogen is added to the chamber for operation 558. Similarly, the chamber pressure and / or tungsten delivery pressure may be increased in operation 558.

[0078] Figure 5C is a process flow diagram illustrating a method of filling a 3D-NAND structure with tungsten. Figure 5C The method described in can also be applied to other structures having gaps to be filled. The method begins at operation 562, where a tungsten nucleation layer is deposited to conformally line the wordline features with tungsten. Operation 562 can be described above with reference to Figure 2A In some embodiments, a silicon-containing and / or boron-containing reducing agent is used during the deposition of the tungsten nucleation layer. In some embodiments, operation 502 can be omitted, as described above. Next, a bulk tungsten layer is deposited by ALD in operation 564 to fill the wordline features in the structure. Operation 564 can be referred to as Figure 2A Operations 282-290 and / or Figure 2C The timing diagram 200 in FIG. 2 is executed as described above. Once the wordline features are filled, a smooth bulk tungsten layer is deposited outside the wordline features in operation 566. Operation 566 can use one or more of the techniques described above: 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 566 is gradual; for example, nitrogen can be gradually added to the reducing agent pulse as the wordline features near completion. It is also important to note that wordline features may be filled at different times; operation 566 can be performed after some or all features are filled.

[0079] Figure 5D is a process flow diagram illustrating another method of filling a 3D-NAND structure with tungsten. Figure 5DThe method described in can also be applied to other structures having gaps to be filled. The method begins at operation 582, where a thin tungsten nucleation layer is deposited to conformally line the wordline features with tungsten. Operation 582 can be described above with reference to Figure 2A In some embodiments, a silicon-containing and / or boron-containing reducing agent is used during the deposition of the tungsten nucleation layer. However, in Figure 5D In the method, the deposited nucleation layer is thinner than that deposited by other methods. The nucleation layer in operation 582 can range from approximately 15 angstroms to 25 angstroms, as opposed to the 25 angstroms to 40 angstroms that can be used in certain other embodiments. Reducing the nucleation thickness can effectively change the density of nucleation sites, thereby adjusting the grain size of the crystal growth and reducing roughness. A tungsten nucleation layer of less than 20 angstroms can be used. However, one disadvantage of reducing the grain size can be an increase in resistivity. If the nucleation layer is not fully converted, the resistivity may increase due to excess boron from the reducing agent in the nucleation layer. In some embodiments, operation 582 involves reducing excess boron residue by increasing argon dilution and / or increasing the exposure time of the tungsten precursor. For example, in some embodiments, the B2H6:Ar dilution is at least 1:5 or 1:9. This is an increase compared to the 1:3 dilution used in certain other nucleation layer deposition methods. The dilution can be increased even further, but at levels such as 1:20, step coverage may be poor. In some embodiments, the dilution level is, for example, 1:5-1:12. In some embodiments, the duration of the tungsten precursor pulse is longer than the duration of the reducing agent pulse, for example, at least 1.5 or 2 times the duration of the reducing agent pulse.

[0080] 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 in lieu of limiting boron incorporation in operation 582. In some embodiments, operation 584 may be omitted if the resistance increase is effectively mitigated in operation 584. If operation 584 is performed, operation 584 involves ALD using pulses of WF6 (or other tungsten precursor) and a H2 reducing agent at a low temperature between 250°C and 350°C, or in some embodiments, between 250°C and 325°C, or between 250°C and 300°C. In some embodiments, a temperature of less than 300°C may be used. An exemplary thickness of the template film may be 20 angstroms to 50 angstroms, or approximately 30 angstroms. This low temperature template layer provides a better 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 can also be performed by ALD WF6 / H2 operation (or using other tungsten precursors), but at higher temperatures (e.g., 350°C-450°C, or above 375°C). An example of a total tungsten deposition can be about 300 angstroms, which includes the nucleation layer, template layer, and bulk layer. In some embodiments, for example, the deposition sequence can involve: ALD deposition of tungsten nucleation layer: WF6 / B2H6 pulses ALD deposition of the template layer: WF6 / H2 pulses at 250°C–350°C; Raising the substrate temperature, for example, by at least 50°C; ALD deposition of bulk layer: WF6 / H2 pulse at 350℃-450℃.

[0081] Figure 5D The method described in can also be implemented in combination with any of the above methods. Figures 5A-5C Any of the methods described is performed by depositing a thin tungsten nucleation layer as described above, with or without a subsequent template layer. Device

[0082] Any suitable chamber may be used to implement the disclosed embodiments. Exemplary deposition apparatus include various systems, such as and Max, which is available from Lam Research Corp. in Fremont, California, or any of a variety of other commercially available processing systems. In some embodiments, atomic layer deposition (ALD) can be performed at a first station, which is one of two, five, or even more deposition stations located in a single deposition chamber. Thus, for example, a separate gas supply system can be used at a first station to introduce diborane (B2H6) and tungsten hexafluoride (WF6) in alternating pulses into the surface of the semiconductor substrate, thereby generating a local atmosphere at the substrate surface. Another station can be used for tungsten bulk layer deposition. Another station can be used for depositing a cap layer by CVD. Two or more stations can be used to deposit tungsten in parallel processing. Alternatively, the wafer can be indexed to perform operations sequentially on two or more stations.

[0083] Figure 6 6 is a schematic diagram of a processing system suitable for performing a deposition process according to an embodiment. System 600 includes a transfer module 603. The transfer module 603 provides a clean, pressurized environment to minimize the risk of contamination of the substrate being processed as it moves between the various reactor modules. According to various embodiments, a multi-station reactor 609 is mounted on the transfer module 603, and the multi-station reactor 609 is capable of performing ALD and CVD. The multi-station reactor 609 may include a plurality of stations 611, 613, 615, and 617, which may perform operations sequentially according to the disclosed embodiments. For example, according to various embodiments, the 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. In some embodiments, station 615 may also perform an ALD tungsten deposition operation, and station 617 may perform a CVD operation.

[0084] The station may include a heated pedestal or substrate support, one or more gas inlets or showerheads, or a dispersion plate. Figure 7 An example of a deposition station 700 is shown in FIG, which includes a substrate support 702 and a showerhead 703. A heater may be provided in the base portion 701.

[0085] Return to Figure 6Also mounted on the transfer module 503 may be one or more single-station or multi-station modules 607 capable of performing plasma or chemical (non-plasma) pre-cleaning, other deposition operations, or etching operations. The modules may also be used for various processes, such as preparing substrates for deposition processes. The system 600 also includes one or more wafer source modules 601, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 619 may first move the wafers from the source module 601 to the load lock 621. The wafer transfer device (typically a robotic arm unit) in the transfer module 603 moves the wafers from the load lock 621 to the modules mounted on the transfer module 603 and moves the wafers between these modules.

[0086] In various embodiments, a system controller 629 is used to control process conditions during the deposition process. The controller 629 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, a stepper motor controller board, etc.

[0087] The controller 629 controls all deposition device activities. The system controller 629 runs system control software, which includes an instruction set for controlling timing, gas mixing, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power level, wafer chuck or susceptor position, and other parameters of a particular process. In some embodiments, other computer programs stored on a memory device associated with the controller 629 may be used.

[0088] Typically, there will be a user interface associated with the controller 629. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and a user input device such as a pointing device, keyboard, touch screen, microphone, or the like.

[0089] The system control logic can be configured in any suitable manner. Generally, the logic can be designed or configured in hardware and / or software. The instructions for controlling the driver circuits can be hard-coded or provided as software. The instructions can be provided through "programming." Such programming is understood to include any form of logic, including hard-coded logic in digital signal processors, application-specific integrated circuits, and other devices having specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that can be executed on a general-purpose processor. The system control software can be encoded in any suitable computer-readable programming language.

[0090] The computer program code for controlling the germanium-containing reducing agent pulses, hydrogen gas flow, and tungsten-containing precursor pulses, as well as other processes in the process sequence, can be written in any conventional computer-readable programming language, such as assembly language, C, C++, Pascal, Fortran, or others. The compiled object code or script is executed by a processor to perform the tasks identified in the program. As also indicated, the program code can be hard-coded.

[0091] Controller parameters relate to process conditions such as, for example, process gas composition and flow rate, 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 can be input using a user interface.

[0092] Signals for monitoring the process may be provided via analog and / or digital input connections of the system controller 629. Signals for controlling the process may be output via analog and digital output connections of the deposition apparatus 600.

[0093] The system software can be designed or configured in many different ways. For example, a plurality of chamber component subroutines or control objects can be written to control the operation of the chamber components required to perform a deposition process according to the disclosed embodiments. Examples of programs or program segments for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0094] In some embodiments, the controller 629 is part of a system, which can be part of the above-described embodiments. Such a system includes a semiconductor processing apparatus that includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems can be integrated with electronic devices to control the operation of these systems before, during, or after processing of semiconductor wafers or substrates. The electronic devices can be referred to as "controllers" and can control various components or sub-parts of one or more systems. Depending on the processing requirements and / or the type of system, the controller 629 can be programmed to control any of the processes disclosed herein, including controlling the 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 rate settings, fluid delivery settings, position and operation settings, wafer entry and exit tools and other transfer tools and / or transfer of load locks connected to or interfaced with a particular system.

[0095] In a broad sense, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit can include a chip that stores program instructions in the form of firmware, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions delivered to the controller or system in the form of various different settings (or program files), and the different settings (or program files) define operating parameters for performing specific processes on or for a semiconductor wafer. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps in the manufacturing process of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or bare chips of a wafer.

[0096] In some embodiments, the controller 629 can be part of or coupled to a computer that is integrated with, coupled to, or connected to the system via a network, or a combination thereof. For example, the controller 629 can be in the "cloud" or all or part of a main computer system in a wafer fab, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, review the history of past manufacturing operations, review trends or performance metrics across multiple manufacturing operations, change parameters of the current process, set processing steps to follow the current process, or start a new process. In some embodiments, a remote computer (e.g., a server) can provide process recipes to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that allows for the input or programming of parameters and / or settings, which are then transmitted 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 these parameters can be specific to the type of process to be performed and the type of tool the controller is configured to connect to or control. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers that are connected together via a network and work toward a common goal (e.g., the process and control described herein). An example of a distributed controller for these purposes would be one or more integrated circuits within the chamber that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which combine to control the process within the chamber.

[0097] Exemplary systems may include, but are not limited to, plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, CVD chambers or modules, ALD chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the preparation and / or fabrication of semiconductor wafers.

[0098] As described above, depending on the process step or steps to be performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, combination tools, other tool interfaces, adjacent tools, adjoining tools, tools located throughout the fab, a host computer, another controller, or tools used in material handling to move containers of wafers to and from tool locations and / or load ports in a semiconductor fabrication facility.

[0099] The controller 629 may include various programs. A substrate positioning program may include program code for controlling chamber components used to load a substrate onto a susceptor or chuck and control the spacing between the substrate and other components of the chamber, such as a gas inlet and / or a target. A process gas control program may include code for controlling gas composition, flow rate, pulse duration, and optionally, for flowing gas into the chamber to stabilize the pressure in the chamber prior to deposition. A pressure control program may include code for controlling the pressure in the chamber by adjusting, for example, a throttle valve in an exhaust system in 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.

[0100] Examples of chamber sensors that can be monitored during deposition include mass flow controllers, pressure sensors such as manometers, and thermocouples located in the susceptor or chuck. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain desired process conditions.

[0101] The apparatus may include a gas manifold system that provides charges to various gas distribution lines, such as Figure 8Schematically shown. 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 via valved distribution lines 805, 813, and 825, respectively. Various valves are opened or closed to provide line material, i.e., to pressurize the distribution lines. For example, to pressurize distribution line 805, valve 806 is closed to vacuum and valve 808 is closed. After a suitable time increment, valve 808 is opened and the tungsten-containing precursor gas is delivered to the chamber. In some embodiments, filling the tungsten precursor to a high pressure (e.g., to 400 Torr) during ALD deposition of the bulk layer can increase resistivity. After a suitable time for the gas to be delivered, valve 808 is closed. The chamber can then be purged to vacuum by opening valve 806 toward vacuum.

[0102] A similar process is used to deliver reducing gas and purge gas. For example, to introduce reducing gas, distribution line 813 is filled by closing valve 815 and closing valve 817 toward the vacuum. Valve 815 is opened to enable the delivery of reducing gas to the chamber. Similarly, to introduce purge gas, distribution line 825 is filled by closing valve 827 and closing valve 823 toward the vacuum. Opening valve 827 enables the delivery of argon or other inert purge gas to the chamber. The amount of time allowed for line filling will change the amount and timing of the initial gas delivery.

[0103] Figure 8 A vacuum pump is also shown, where valves 806, 817, and 823 can be opened to purge the system, respectively. The supply of gas through the various distribution lines is controlled by a controller (e.g., a mass flow controller) controlled by a microprocessor, digital signal processor, or the like, which is programmed with the flow rate, flow duration, and sequence of processes.

[0104] Note that the above process may require precise timing of valves and mass flow controllers (MFCs) to deliver reagent pulses to the semiconductor substrate during deposition. In one approach to making this possible, valve and MFC commands are transmitted to an embedded digital input-output controller (IOC) in discrete packets containing instructions for all time-critical commands for all or part of a deposition sequence. Lam Research's ALTUS system provides at least one IOC sequence. The IOC can be physically located at different locations in the apparatus; for example, within a process module or on a separate power rack located some distance from the process module. There can be multiple IOCs in each module (e.g., three per module). Regarding the actual instructions contained in the sequence, all commands for controlling valves and setting MFC flows (for all carrier and reactant gases) can be contained within a single IOC sequence. This ensures that the timing of all equipment is tightly controlled both in absolute terms and in relation to each other. There are typically multiple IOC sequences running at any given time. This enables, for example, ALD to be run at stations 1-2, where all the timing of all hardware components required to deposit the ALD-W nucleation layer at those stations is controlled. A second sequence may be run simultaneously to deposit a tungsten body at other deposition stations in the same module using the above timing. The relative timing of the equipment controlling the delivery of reagents to stations 3-4 is important within this group of equipment, but the relative timing of the ALD process at stations 1-2 can deviate from the relative timing of stations 3-4. The IOC converts the information in a packaged sequential manner and transmits digital or analog command signals directly to the MFC or pneumatic solenoid valve group that controls the valves.

[0105] The pulse of tungsten-containing gas can be generated as follows. Initially, when the MFC or other flow control device is stable, the system transfers WF6 to the vacuum pump for a period of time. In one example, this can be done in a time period of about 0.5 to 5 seconds. Next, the system pressurizes the tungsten gas delivery manifold by closing the diverting outlet 606 and outlet 608 leading to the deposition chamber. This can be done in a time period of about 0.1 to 5 seconds, for example to produce an initial burst of reagent when the outlet of the deposition chamber is opened. In one example, this is achieved by opening the outlet valve 808 for a time period of about 0.1 to 10 seconds. Thereafter, the tungsten-containing gas is purged from the deposition chamber using a suitable purge gas. Pulsed flows of other reagents can be performed in a similar manner.

[0106] The foregoing describes embodiments of the present invention as implemented in a single-chamber or multi-chamber semiconductor processing tool. The apparatus and processes described herein can be used in conjunction with photolithographic patterning tools or processes, for example, for preparing or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, and the like. Typically, though not necessarily, these tools / processes will be used or operated together in a common manufacturing facility. Photolithographic patterning of films typically includes some or all of the following steps, each of which utilizes multiple available tools: (1) applying photoresist to a workpiece, i.e., a substrate, using a spin coating or spray coating tool; (2) curing the photoresist using a hot plate or oven or UV curing tool; (3) exposing the photoresist to visible light or UV light or X-rays using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist and thereby pattern it using a tool such as a wet cleaning station; (5) transferring the resist pattern to an underlying film or workpiece using a dry or plasma assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper. in conclusion

[0107] Although the above embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be implemented within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the embodiments of the present invention. Therefore, the embodiments of the present invention are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

1. A method comprising: (a) Deposition of 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 applying alternating pulses of a tungsten precursor and hydrogen (H2) when the substrate temperature is below 300° C.; as well as (c) After (b), depositing a bulk layer of tungsten by alternating pulses of a tungsten precursor and hydrogen (H2) gas when the substrate temperature is at least 350°C.

2. The method according to claim 1, wherein The thickness of the deposited tungsten nucleation layer does not exceed 30 angstroms.

3. The method according to claim 1, wherein The tungsten precursor in step (a) is tungsten hexafluoride. The method according to claim 1 , wherein the second tungsten precursor in step (b) is tungsten hexafluoride. The method according to claim 1 , wherein the tungsten precursor in step (c) is tungsten hexafluoride. The method according to claim 1 , wherein the tungsten precursor in step (a) is a chlorine-containing tungsten precursor.

7. The method according to claim 1, wherein the tungsten precursor in step (b) is a chlorine-containing tungsten precursor. The method according to claim 1 , wherein the tungsten precursor in step (c) is a chlorine-containing tungsten precursor.

9. The method of claim 1, wherein the pulse of tungsten precursor in step (c) is delivered at a pressure of at least 300 Torr.

10. The method of claim 1, wherein in step (b), H2 pulses are co-flowed with N2.

11. The method of claim 10, wherein the delivery pressure of the tungsten precursor pulse is higher than the pulse pressure of the H2 and N2 co-flow in step (b).

12. The method of claim 10, wherein N2 accounts for 10-30% (vol.) of the total flow of N2+H2 in the H2 and N2 co-flow pulse.

13. The method of claim 1, wherein in step (c), H2 pulses are co-flowed with N2.

14. The method of claim 13, wherein the delivery pressure of the tungsten precursor pulse is higher than the pulse pressure of the H2 and N2 co-flow in step (c).

15. The method according to claim 14, wherein N2 accounts for 10-30% (vol.) of the total N2+H2 flow in the H2 and N2 co-flow pulse.

16. The method according to claim 1, wherein In step (a), a tungsten precursor pulse is delivered in the absence of nitrogen.

17. The method according to claim 1, wherein In step (a), a tungsten precursor pulse is delivered in the absence of nitrogen.

18. The method according to claim 1, wherein In step (c), the substrate temperature is between 350°C and 450°C.

19. The method according to claim 1, wherein In step (c), the substrate temperature is higher than 375°C.

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