Method for seamless gap filling using gradient oxidation

Abstract

To provide processing methods for seamless gap filling of high aspect ratio structures.SOLUTION: Methods comprise forming a metal gate film on a narrow feature and a wide feature, and depositing a hard mask on the metal gate film. The hard mask forms on the metal gate film at a top, bottom and sidewalls of the wide feature and on a top of the narrow feature so as to cover the metal gate film. The methods further comprise oxidizing the metal gate film on the narrow feature to convert a portion of the metal gate film into a metal oxide film, etching the metal oxide film from the narrow feature to leave a gradient etch profile, and filling the narrow feature and the wide feature with a gap fill material comprising one or more of a metal nitride, titanium nitride (TiN) and titanium oxynitride (TiON), the gap fill material substantially free of seams and voids.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 254,015, filed on 8 October 2021, the entire disclosure of which is incorporated herein by reference.

[0002]

[0002] Embodiments of the present disclosure relate more broadly to methods for filling gaps in high aspect ratio structures. In particular, embodiments of the present disclosure relate to methods for seamlessly filling gaps in high aspect ratio structures. [Background technology]

[0003]

[0003] In the manufacture of microelectronic devices, many applications require filling narrow trenches with an aspect ratio (AR) greater than 10:1 without generating voids. One application is shallow trench isolation (STI). In this application, the film needs to be of high quality with a very low leakage rate throughout the trench (for example, having a wet etching rate ratio of less than 2).

[0004]

[0004] Ultra-high density memory devices can be manufactured using a three-dimensional (3D) stacked memory structure. For example, a 3D NAND stacked memory device can be formed from an array of alternating conductive and dielectric layers. Memory holes are formed through the memory layers, and NAND strings are formed by filling the memory holes with a suitable material. As the dimensions of the structure decrease and the aspect ratio increases, the post-curing method of the deposited film becomes more difficult.

[0005]

[0005] Filling metal gate stacks in gate trenches has become increasingly difficult with device scaling. One aspect of device scaling is seamless gap filling to avoid problems in downstream integration processes in advanced node applications. The challenge in device scaling down relates to gap filling processes where both wide and narrow structures exist. The challenge is to generate seamless or voidless gap filling in narrow features without affecting overall device performance by adversely impacting wide features. Although not bound by any particular operating theory, oxidation in wide features is considered to adversely affect overall device performance.

[0006]

[0006] Therefore, in the art, there is a need for a method of seamlessly filling gaps in high aspect ratio structures. [Overview of the project]

[0007]

[0007] One or more embodiments of the present disclosure relate to a processing method. The processing method includes depositing a hard mask on a metal gate film formed on a substrate surface having narrow features and wide features. The narrow features have an aspect ratio of about 15 or more, and the wide features have an aspect ratio of 3 or less. The hard mask is formed on the metal gate film at the top, bottom, and sidewalls of the wide features and on the metal gate film on the top of the narrow features so as to cover the metal gate film, while substantially no hard mask is formed on the bottom and sidewalls of the narrow features, leaving the metal gate film intact. The processing method further includes oxidizing the metal gate film within the narrow features to convert a portion of the metal gate film into a metal oxide film. The metal oxide film is formed as a gradient oxide layer, with the amount of metal oxide decreasing from the top to the bottom of the narrow features. The processing method further includes etching the metal oxide film from the narrow features to leave a gradient etching profile.

[0008]

[0008] Another embodiment of the present disclosure relates to a processing method. The processing method comprises performing at least one process cycle, each process cycle comprising depositing a hard mask on a metal gate film formed on a substrate surface having narrow features and wide features. The narrow features have an aspect ratio of about 15 or more, and the wide features have an aspect ratio of 3 or less. The hard mask is formed on the metal gate film at the top, bottom, and sidewalls of the wide features and on the metal gate film on the top of the narrow features so as to cover the metal gate film, while substantially no hard mask is formed on the bottom and sidewalls of the narrow features, leaving the metal gate film intact. Each process cycle further comprises oxidizing the metal gate film within the narrow features to convert a portion of the metal gate film into a metal oxide film. The metal oxide film is formed as a gradient oxide layer, with the amount of metal oxide decreasing from the top to the bottom of the narrow features. Each process cycle further comprises etching the metal oxide film from the narrow features to leave a gradient etching profile. The processing method further comprises filling narrow and wide features with a gap-filling material comprising one or more of metal nitrides, titanium nitride (TiN), and titanium oxynitride (TiON), wherein the gap-filling material is substantially free of seams and voids.

[0009]

[0009] Further embodiments of the present disclosure relate to processing methods. The processing method comprises (a) depositing a hard mask containing carbon onto a metal gate film formed on a substrate surface having narrow features and wide features. The narrow features have an aspect ratio of 20 and a width in the range of 2 nm to 10 nm, and the wide features have an aspect ratio of 1.5 and a width in the range of 50 nm to 300 nm. The hard mask is formed on the metal gate film at the top, bottom, and sidewalls of the wide features and on the metal gate film on the top of the narrow features so as to cover the metal gate film, while substantially no hard mask is formed on the bottom and sidewalls of the narrow features, leaving the metal gate film intact. The processing method further comprises (b) oxidizing the metal gate film within the narrow features to convert a portion of the metal gate film into a metal oxide film. The metal oxide film is formed as a gradient oxide layer, with the amount of metal oxide decreasing from the top to the bottom of the narrow feature. The processing method further comprises (c) etching the metal oxide film from the narrow features to leave a gradient etch profile. The processing method further comprises (d) repeating (a) through (c) 10 times or less. The processing method further comprises (e) filling the narrow and wide features with a gap-filling material containing titanium oxynitride (TiON).

[0010]

[0010] To enable a detailed understanding of the features of the present disclosure described above, a more specific description of the present disclosure, which has been briefly summarized above, can be obtained by reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings show only typical embodiments of the present disclosure and therefore should not be considered to limit the scope of the present disclosure, as the present disclosure may allow for other equally valid embodiments. [Brief explanation of the drawing]

[0011] [Figure 1]

[0011] One or more embodiments of the present disclosure show an electronic device having narrow features and wide features formed in a substrate. [Figure 2]

[0012] Figure 1 shows the electronic device after forming a metal gate film on narrow and wide features. [Figure 3]

[0013] Figure 2 shows the electronic device after a hard mask has been formed on the substrate surface at the tops of narrow and wide features to cover the metal gate film. [Figure 4]

[0014] Figure 3 shows the electronic device after a portion of the metal gate film has been oxidized to form a metal oxide film on narrow features and on the sidewalls of wide features. [Figure 5]

[0015] Figure 4 shows the electronic device after etching the metal oxide film on narrow and wide features. [Figure 6]

[0016] The following are electronic devices of one or more embodiments after optionally repeating a process cycle in which a hard mask is formed, a metal gate film is oxidized, and a metal oxide film is etched. [Figure 7]

[0017] One or more embodiments of an electronic device are shown after the hard mask has been optionally removed. [Figure 8]

[0018] One or more embodiments of an electronic device are shown after selectively filling gaps between narrow and / or wide features. [Figure 9]

[0019] The process flow diagrams of processing methods according to one or more embodiments of this disclosure are shown. [Modes for carrying out the invention]

[0012]

[0020] Before describing some exemplary embodiments of this disclosure, it should be understood that this disclosure is not limited to the configuration or process step details presented in the following description. Other embodiments of this disclosure are possible and can be implemented or performed in a variety of ways.

[0013]

[0021] As used in the present specification and the appended claims, the terms "substrate" and "wafer" are used interchangeably, and both refer to the surface or a portion of the surface on which a process acts. As will be understood by those skilled in the art, when reference is made to a substrate, it may refer to only a portion of the substrate unless the context explicitly indicates otherwise. Furthermore, reference to deposition on a substrate can refer to both a bare substrate and a substrate having one or more layers or features deposited or formed on the surface thereof.

[0014]

[0022] As used herein, the term "substrate" refers to any substrate or a material surface formed on a substrate on which film treatment is performed during a manufacturing process. For example, depending on the application, the substrate surface on which treatment may be performed includes materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. The substrate includes, but is not limited to, a semiconductor wafer. The substrate may be exposed to a pretreatment process of polishing, etching, reducing, oxidizing, hydroxylating (or otherwise generating or grafting target chemical moieties to impart chemical functionality), annealing and / or baking the substrate surface. In addition to performing film treatment directly on the surface of the substrate itself, in the present disclosure, any of the disclosed film treatment steps may be performed on an underlayer formed on the substrate, which is disclosed in more detail below. The term "substrate surface" is intended, as the context indicates, to include such underlayers. Accordingly, for example, where a film / layer or partial film / layer is deposited on the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface. What a given substrate surface comprises depends on which films are deposited and the specific chemical properties employed.

[0015]

[0023] According to one or more embodiments, the term "on" as it relates to a film or a layer of a film encompasses both that the film or layer is present directly on a surface, for example a substrate surface, and that one or more underlying layers are present between the film or layer and the surface, for example the substrate surface. Accordingly, in one or more embodiments, the phrase "on the substrate surface" is intended to encompass one or more underlying layers. In other embodiments, the phrase "directly on" refers to a layer or film that is in contact with a surface (e.g., a substrate surface) with no intervening layers. Accordingly, the phrase "a layer directly on a substrate surface" refers to a layer that is in direct contact with the substrate surface, with no layers between them.

[0016]

[0024] Referring to FIGS. 1 to 8, there is shown an electronic device 10 having narrow features 100 and wide features 200 formed in a substrate 50. The narrow features 100 and wide features 200 extend in a depth direction from a substrate surface 52 into the substrate 50, as described below. FIG. 9 illustrates a processing method for forming any of the features (e.g., narrow features 100 and wide features 200) of one or more embodiments shown in FIGS. 1 to 8. The narrow features 100 and wide features 200 shown in the drawings have a rectangular cross-section. However, this is merely representative of one possible configuration, and those skilled in the art will recognize that the shape of the narrow features 100 and wide features 200 may be any suitable shape, including but not limited to elongated trenches with rounded or angular corners and cylindrical vias. Suitable non-limiting examples of features include trenches having a top (a substrate surface immediately adjacent the trench), two sidewalls and a bottom, peaks having a top and two sidewalls, and circular vias having continuous sidewalls. The processes and layers / films performed herein may be described with reference to narrow features 100 and / or wide features 200, as indicated by the relevant context.

[0017]

[0025] Figure 1 shows a narrow feature 100 having a top 110, side walls 120, and a bottom 130. The top 110 of the narrow feature 100 is a region of the substrate surface 52 adjacent to the opening indicated by the side walls 120 of the narrow feature 100. The narrow feature 100 has a height H1, measured as the depth of the narrow feature 100 extending from the substrate surface 52 to the bottom 130. In some embodiments, the height H1 is in the range of 25 nm to 1000 nm, or 50 nm to 500 nm, or 75 nm to 250 nm, or 100 nm to 200 nm. In one or more embodiments, the narrow feature 100 has a width W1 in the range of 2 nm to 10 nm. The width W1 is measured as the average distance between the side walls 120 measured at equal distances from the bottom 130. In one or more embodiments, the narrow feature 100 has an aspect ratio of 15 or more (measured as the ratio of height H1 to width W1). In one or more embodiments, the aspect ratio of the narrow feature 100 is 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, or 50 or more.

[0018]

[0026] The broad feature 200 has a top 210, sidewalls 220, and a bottom 230. The top 210 of the broad feature 200 is a region of the substrate surface 52 adjacent to the opening indicated by the sidewalls 220 of the broad feature 200. The broad feature 200 has a height H2 measured as the depth of the broad feature 200 extending from the substrate surface 52 to the bottom 230. In some embodiments, the height H2 is in the range of 25 nm to 1000 nm, or 50 nm to 500 nm, or 75 nm to 250 nm, or 100 nm to 200 nm. In some embodiments, the height H2 of the broad feature 200 is within ±5%, ±2%, or ±1% of the height H1 of the narrow feature 100. The broad feature 200 has a width W2 in the range of 50 nm to 300 nm. In one or more embodiments, the broad feature 200 has an aspect ratio of 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 or less (measured as the ratio of height H2 to width W2).

[0019]

[0027] Figure 2 shows the electronic device 10 of Figure 1 after the formation of the metal gate film 140 by operation 705 of method 700. The metal gate film 140 is deposited on the narrow feature 100 and the wide feature 200. In some embodiments, the metal gate film 140 is a conformal film. In some embodiments, the metal gate film 140 is a non-conformal film.

[0020]

[0028] The metal gate film 140 can be any suitable material known to those skilled in the art. In some embodiments, the metal gate film 140 comprises one or more of the following: titanium aluminum carbide (TiAlC), titanium nitride (TiN), tantalum nitride (TaN), tungsten nitride (WN), silicon nitride (SiN), or aluminum nitride (AlN). In some embodiments, the metal gate film 140 has a thickness in the range of 1 nm to 30 nm, or in the range of 2 nm to 15 nm.

[0021]

[0029] Figure 3 shows the electronic device 10 of Figure 2 after the formation of the hard mask 150 by operation 710 of method 700. In some embodiments, the hard mask 150 comprises one or more of carbon (C), titanium nitride (TiN), titanium oxynitride (TiON), silicon dioxide (SiO2), or silicon nitride (SiN). The hard mask 150 can be deposited by any suitable technique known to those skilled in the art. In one or more embodiments, the hard mask 150 is deposited on the metal gate film 140 by chemical vapor deposition (CVD) or physical vapor deposition (PVD). In some embodiments, the hard mask 150 is deposited by physical vapor deposition (PVD).

[0022]

[0030] In some embodiments, as shown in Figure 3, the hard mask 150 is formed on the substrate surface at the top 110 of the narrow feature 100 and the top 210 of the wide feature so as to cover the metal gate film 140. In one or more embodiments, the hard mask 150 is not substantially formed on the metal gate film 140 at the bottom 130 of the narrow feature 100 or on the sidewall 120, leaving the metal gate film 140 exposed. Those skilled in the art will recognize that some hard mask 150 may be formed on the upper portion of the sidewall of the narrow feature 100, as shown in Figure 3. When used in this manner, the term “not substantially formed” means that the hard mask 150 on the bottom 130 of the narrow feature 100 and the hard mask 150 on the bottom two-thirds of the sidewall 120 of the narrow feature 100 has an average thickness of about 5%, 2%, or 1% or less of the thickness of the hard mask 150 on the top 110 of the narrow feature 100. In one or more embodiments, the hard mask 150 on the top 110 of the narrow feature 100 has a thickness ranging from 10 Å to 1000 Å.

[0023]

[0031] As shown in Figure 3, the hard mask 150 is formed on the top 210, bottom 230, and sidewalls 220 of the broad feature 200. In one or more embodiments, the hard mask 150 on the top 210 of the broad feature 200 has a thickness ranging from 10 Å to 1000 Å. In one or more embodiments, the hard mask 150 on the bottom 230 and sidewalls 220 of the broad feature 200 has a thickness ranging from 10 Å to 1000 Å. In some embodiments, the thickness of the hard mask 150 formed on the sidewalls 220 and bottom 230 of the broad feature 200 is smaller than the thickness of the hard mask 150 formed on the top 210 of the broad feature 200.

[0024]

[0032] FIG. 4 illustrates the electronic device 10 of FIG. 3 after oxidizing a portion of the metal gate film 140 according to operation 720 of method 700. Oxidizing a portion of the metal gate film 140 forms a graded metal oxide film 160 over the narrow feature 100. In one or more embodiments, in operation 720, oxidizing the metal gate film 140 comprises exposing the metal gate film 140 to one or more of oxidizing plasma or oxygen radicals. The plasma may be any suitable oxidizing plasma known to those skilled in the art. In one or more embodiments, the oxidizing plasma comprises one or more of oxygen (O₂), nitrous oxide (N₂O), water (H₂O), ozone (O₃), inductively coupled plasma (ICP) thereof, or capacitively coupled plasma (CCP) thereof. In one or more embodiments, the oxidizing plasma has a high ion concentration. In one or more embodiments, the oxidizing plasma having a high ion concentration has about 10 10 / cm 3 or higher ion concentration, or about 10 9 / cm 3 , 10 11 / cm 3 , 10 12 / cm 3 , 10 13 / cm 3 , or 10 14 / cm 3 or higher ion concentration. The oxidizing plasma used for processing may be any suitable plasma that can modify film properties (e.g., direct or remote). In one or more embodiments, about 5% of the metal gate film 140 is converted to the metal oxide film 160. In one or more embodiments, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the metal gate film 140 is converted to the metal oxide film 160.

[0025]

[0033] In one or more embodiments, the metal oxide film 160 is formed as a gradient oxide layer, and the thickness of the metal oxide film decreases from the top 110 of the narrow feature 100. In one or more embodiments, the amount of metal oxide at the top 110 of the narrow feature 100 has a thickness in the range of 500 Å to 1000 Å. In one or more embodiments, the amount of metal oxide at the midpoint between the top 110 and the bottom 130 of the narrow feature 100 has a thickness in the range of 100 Å to 500 Å. In one or more embodiments, the amount of metal oxide at the bottom 130 of the narrow feature 100 has a thickness in the range of 10 Å to 100 Å.

[0026]

[0034] In some embodiments, oxidation of the metal gate film 140 removes the hard mask 150 on the sidewall of the broad feature 200 and / or oxidizes a portion of the metal gate film 140 formed on the sidewall of the broad feature 200. Figure 4 shows the metal oxide film 160 on the sidewall 220 of the broad feature 200. In one or more embodiments, the metal oxide film 160 on the sidewall 220 of the broad feature 200 has a thickness ranging from 10 Å to 1000 Å.

[0027]

[0035] While not bound by any particular theory of operation, in operation 710, forming a hard mask 150 on the metal gate film 140 on the narrow feature 100 favorably enables, in operation 720, the oxidation of the metal gate film 140 without damaging it. While not bound by any particular theory of operation, in operation 710, forming a hard mask 150 on the metal gate film 140 on the narrow feature, and then in operation 720, oxidizing the metal gate film 140, enables the formation of a "V" shaped narrow feature 100.

[0028]

[0036] The metal oxide film 160 comprises any suitable oxide known to those skilled in the art. The metal oxide film 160 formed is the oxide of the metal gate film 140 formed in operation 705 of method 700. In some embodiments, the metal oxide film 160 comprises one or more of titanium oxynitride (TiON), tantalum oxynitride (TaON), tungsten oxynitride (WON), silicon oxynitride (SiON), and aluminum oxynitride (AlON).

[0029]

[0037] Figure 5 shows the electronic device 10 of Figure 4 after etching by operation 730 of method 700. The substrate 50 may be etched and / or the metal oxide film 160 may be selectively removed by any process known to those skilled in the art. Such processes include, but are not limited to, wet etching, plasma-based sputter etching, chemical etching, Siconi® etching, reactive ion etching (RIE), high-density plasma (HDP) etching, chemical mechanical planarization (CMP), and the like. In one or more embodiments, etching the metal oxide film 160 in operation 730 includes exposing the metal oxide film 160 to one or more of the following: metal halides, chlorine (Cl2), nitrogen trifluoride (NF3), tantalum pentachloride (TaCl5), tungsten pentachloride (WCl5), or tungsten dioxide dichloride (WO2Cl2). In one or more embodiments, the metal oxide film 160 is completely removed from the narrow feature 100. In one or more embodiments, the metal oxide film 160 is substantially absent on the narrow feature 100. Thus, the phrase “substantially absent metal oxide film 160” means that approximately 5%, 2%, or less than 1% of the metal oxide film 160 formed in operation 720 (see Figure 4) remains after etching.

[0030]

[0038] In one or more embodiments, the metal oxide film 160 is etched from the narrow feature 100, leaving a gradient etching profile. In one or more embodiments, etching by operation 730 reduces the thickness of the metal oxide film 160 on the narrow feature 100. In some embodiments, after etching by operation 730, the amount of metal oxide at the top 110 of the narrow feature 100 has a thickness ranging from 10 Å to 50 Å. In some embodiments, after etching by operation 730, the amount of metal oxide at the midpoint between the top 110 and bottom 130 of the narrow feature 100 has a thickness ranging from 5 Å to 30 Å. In other embodiments, after etching by operation 730, the amount of metal oxide at the bottom 130 of the narrow feature 100 has a thickness ranging from 0 Å to 10 Å.

[0031]

[0039] Figure 5 also shows the result of etching the metal oxide film 160 on the broad feature 200 according to operation 730. In one or more embodiments, the metal oxide film 160 is completely removed from the broad feature 200. In one or more embodiments, the metal oxide film 160 is substantially absent on the broad feature 200. Thus, the term “substantially absent” means that about 5%, 2%, or 1% or less of the metal oxide film 160 formed by operation 720 (see Figure 4) remains after etching. In one or more embodiments, etching by operation 730 reduces the thickness of the metal oxide film 160 on the broad feature 200. In some embodiments, after etching by operation 730, the metal oxide film 160 on the sidewall 220 of the broad feature 200 has a thickness ranging from 5 Å to 30 Å.

[0032]

[0040] In some embodiments, the processing method 700 optionally includes repeating a portion of the processing method described herein in operation 740. In one or more embodiments, operations 710, 720, and 730 are repeated to deposit a hard mask on the metal gate film, oxidize the metal film in the narrow feature to form a metal oxide film, and etch the metal oxide film. In one or more embodiments, the cycle includes operations 710, 720, and 730. In one or more embodiments, the optional operation 740 includes repeating the cycle 10 or less times. Figure 6 shows the electronic device 10 after the cycles of operations 710, 720, and 730 have been repeated, resulting in a gradient oxidation profile in the narrow feature 100 that extends to or near the bottom of the feature.

[0033]

[0041] In some embodiments, oxidation and etching result in the formation of a "V"-shaped opening in the narrow feature 100 and / or the wide feature 200. Several embodiments of the present disclosure advantageously provide one or more of the narrow feature 100 or wide feature 200 having a "V" shape. Although not bound by any particular operating theory, the narrow feature 100 and / or wide feature 200 having a "V" shape advantageously allow for improved gap filling.

[0034]

[0042] Figure 7 shows the electronic device 10 of Figure 6 after the hard mask 150 has been removed by an optional operation 750 of method 700. The removal of the hard mask 150 can be carried out, for example, by any suitable technique known to those skilled in the art, depending on the composition of the hard mask. In some embodiments, one or more of the narrow features 100 or wide features 200 have a "V" shape. Figure 7 shows a narrow feature 100 having a "V" shape.

[0035]

[0043] Figure 8 shows the electronic device 10 of Figure 7 after gap filling by operation 760 of method 700. In some embodiments, one or more of the narrow features 100 or wide features 200 have a "V" shape. Figure 8 shows the narrow feature 100 having a "V" shape. The narrow features 100 and wide features 200 are filled with gap-filling material 170. The gap-filling material 170 can be any suitable material deposited by any suitable technique known to those skilled in the art. In some embodiments, the gap-filling material 170 comprises one or more of titanium nitride (TiN) or titanium oxynitride (TiON). In one or more embodiments, the gap-filling material 170 is substantially carbon (C) free. When used in this way, the term "substantially carbon free" means that the gap-filling material 170 contains about 5%, 2%, or 1% or less carbon (C) on an atomic basis. In one or more embodiments, the gap-filling material 170 is substantially seam- and void-free. When used in this manner, terms such as "substantially free of seams and voids" mean that voids or seams constitute less than 1% of the stated volume.

[0036]

[0044] Some or all of the processes and methods of this disclosure may also be executed in hardware. Therefore, the processes may be implemented in software and executed using a computer system in hardware, for example, as an application-specific integrated circuit or other types of hardware implementation or a combination of software and hardware. When executed by a processor, the software routines transform a general-purpose computer into a dedicated computer (controller) that controls the chamber operation so that the processes can be executed.

[0037]

[0045] Multiple embodiments of this disclosure relate to non-temporary computer-readable media. In one or more embodiments, the non-temporary computer-readable media includes instructions, when executed by a controller of a processing chamber, that cause the processing chamber to perform any operation of the processing methods described herein. In one or more embodiments, the processing chamber performs an operation of processing method 700. In one or more embodiments, the processing chamber performs a plurality of operations. The operations include: depositing a hard mask on a metal gate film formed on a substrate surface having narrow and wide features, wherein the narrow features have an aspect ratio of approximately 15 or more, and the wide features have an aspect ratio of 3 or less, and the hard mask is formed on the metal gate film at the top, bottom, and sidewalls of the wide features and on the metal gate film on the top of the narrow features so as to cover the metal gate film, and substantially not forming a hard mask on the bottom and sidewalls of the narrow features, leaving the metal gate film as is; oxidizing the metal gate film within the narrow features to convert a portion of the metal gate film into a metal oxide film, wherein the metal oxide film is formed as a gradient oxide layer in which the amount of metal oxide decreases from the top to the bottom of the narrow features; and etching the metal oxide film from the narrow features to leave a gradient etching profile.

[0038]

[0046] According to one or more embodiments, the substrate is processed before and / or after layer formation. This processing may be carried out in the same chamber or in one or more separate processing chambers. In one or more embodiments, deposition / oxidation / etching is performed within the same processing tool.

[0039]

[0047] Several well-known cluster tools that may be adapted to this disclosure are Olympia®, Continuum®, and Trillium®, all available from Applied Materials, Inc. in Santa Clara, California. However, the exact arrangement and combination of the multiple chambers may be modified for the purpose of performing specific steps of the processes described herein. Other processing chambers that may be used include, but are not limited to, periodic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma treatment, etching, pre-cleaning, chemical cleaning, heat treatment such as RTP, plasma nitriding, degassing, hydroxylation, and other substrate processes. Performing chamber processing on a cluster tool can avoid surface contamination of the substrate by airborne impurities without oxidation before subsequent film deposition.

[0040]

[0048] According to one or more embodiments, the substrate is continuously under reduced pressure or "load-lock" conditions and is not exposed to ambient air when moved from one chamber to the next. Thus, the transfer chamber is under reduced pressure and "pumped down" under reduced pressure. An inert gas may be present in the processing chamber or transfer chamber. In some embodiments, an inert gas is used as a purge gas to remove some or all of the reactants (e.g., reactants). According to one or more embodiments, the purge gas is injected at the outlet of the deposition chamber to prevent the reactants (e.g., reactants) from moving from the deposition chamber to the transfer chamber and / or further processing chambers. Thus, a flow of inert gas forms a curtain at the chamber outlet.

[0041]

[0049] The substrates may be processed in a single substrate deposition chamber, where a single substrate is loaded, processed, and unloaded before another substrate is processed. Multiple substrates may also be processed in a continuous manner, similar to a conveyor system, where they are individually loaded into a first section of the chamber, move through the chamber, and unloaded from a second section. The shape of the chamber and associated conveyor system can form a straight or curved path. Furthermore, the processing chamber may be a carousel, where multiple substrates move around a central axis and undergo processes such as deposition, etching, annealing, and cleaning along the carousel path.

[0042]

[0050] During processing, the substrate can be heated or cooled. Such heating or cooling can be achieved by any suitable means, including, but not limited to, changing the temperature of the substrate support and flowing a heated or cooled gas onto the substrate surface. In some embodiments, the substrate support includes a heater / cooler that can be controlled to change the substrate temperature conductively. In one or more embodiments, the gas used (either a reactive or inert gas) is heated or cooled to locally change the substrate temperature. In some embodiments, the heater / cooler is positioned inside the chamber adjacent to the substrate surface to change the substrate temperature by convection.

[0043]

[0051] The substrate can also be stationary or rotated during the process. A rotating substrate can be rotated continuously or discontinuously in steps (around the substrate axis). For example, the substrate may be rotated throughout the entire process, or it may be rotated little by little between exposures to various reactive or purging gases. Rotating the substrate (continuously or in steps) during the process can help minimize the effects of local variability in the gas flow shape, for example, and contribute to the creation of more uniform deposition or etching.

[0044]

[0052] Spatial relative terms such as “down,” “below,” “underside,” “up,” “above,” and “upperside” may be used herein to facilitate the description of the relationship of one element or feature to another (or more) elements or features, as shown in the drawings. It should be understood that spatial relative terms are intended to encompass various orientations of a device in use or operation, in addition to the orientation depicted in the drawings. For example, if a device in a drawing is turned upside down, an element described as “below” or “below” another element or feature will be oriented “above” that other element or feature. Thus, the exemplary term “down” may include both up and down orientations. A device may be oriented in other ways (rotated 90 degrees or to other orientations), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0045]

[0053] In the context of describing the materials and methods described herein (particularly in the context of the following claims), the use of the terms “a” and “an” and “the” and similar references shall be construed to cover both singular and plural, unless otherwise indicated herein or clearly inconsistent with the context. Enumerations of value ranges herein are merely intended to function as abbreviations for each individual value within the range, unless otherwise specifically indicated herein, and each individual value is incorporated into the specification as if it were individually cited herein. All methods described herein may be performed in any suitable order, unless otherwise indicated herein or clearly inconsistent with the context. The use of any and all examples or exemplary words provided herein (e.g., “such as”) is merely intended to better describe the materials and methods and does not limit their scope unless specifically requested. Words in the specification should not be construed to indicate elements not claimed to be essential to the carrying out of the disclosed materials and methods.

[0046]

[0054] Throughout this specification, any reference to “one embodiment,” “certain embodiments,” “one or more embodiments,” or “an embodiment” means that a particular feature, structure, material, or property described in relation to an embodiment is included in at least one embodiment of this disclosure. Therefore, expressions such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment,” or “in an embodiment” in various parts of this specification do not necessarily refer to the same embodiment of this disclosure. In one or more embodiments, a particular feature, structure, material, or property may be combined in any suitable manner.

[0047]

[0055] While the disclosure herein is described with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and uses of the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatus of the disclosure without departing from the spirit and scope of the disclosure. Accordingly, the present invention is intended to include modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. A hard mask is deposited on a metal gate film formed on a substrate surface having narrow features and wide features, wherein the narrow features have an aspect ratio of approximately 15 or more, and the wide features have an aspect ratio of 3 or less, and the hard mask is formed on the metal gate film at the top, bottom, and side walls of the wide features, and on the metal gate film on the top of the narrow features, so as to cover the metal gate film, and substantially not formed on the bottom and side walls of the narrow features, leaving the metal gate film as is, in a manner that deposits the hard mask. The process involves oxidizing the metal gate film within the narrow feature to convert a portion of the metal gate film into a metal oxide film, wherein the metal oxide film is formed as a gradient oxide layer in which the amount of metal oxide decreases from the top to the bottom of the narrow feature. A processing method comprising etching the metal oxide film from the narrow feature to leave a gradient etching profile.

2. The hard mask is made of carbon (C), titanium nitride (TiN), titanium oxynitride (TiON), and silicon dioxide (SiO2). 2 The processing method according to claim 1, comprising one or more of the following: ), and silicon nitride (SiN).

3. The processing method according to claim 1, wherein the hard mask on the top of the broad feature and the top of the narrow feature has a thickness in the range of 10 Å to 1000 Å.

4. The processing method according to claim 1, wherein the hard mask on the bottom and side walls of the broad feature has a thickness of 10 Å or more.

5. The processing method according to claim 1, wherein the aspect ratio of the narrow feature is 20 or more.

6. The processing method according to claim 1, wherein the aspect ratio of the wide feature is 2 or less.

7. The processing method according to claim 1, wherein the narrow feature has a width in the range of 2 nm to 10 nm, and the wide feature has a width in the range of 50 nm to 300 nm.

8. The treatment method according to claim 1, wherein oxidizing the metal gate film includes exposing the metal gate film to one or more of oxidizing plasma and oxygen radicals.

9. The aforementioned oxidizing plasma is oxygen (O 2 ), nitrous oxide (N 2 O), water (H 2 O), ozone (O 3 The processing method according to claim 8, comprising one or more of the following: ), inductively coupled plasma (ICP), or capacitively coupled plasma (CCP).

10. The treatment method according to claim 1, wherein the metal oxide film comprises one or more of titanium oxynitride (TiON), tantalum oxynitride (TaON), tungsten oxynitride (WON), silicon oxynitride (SiON), and aluminum oxynitride (AlON).

11. The processing method according to claim 1, further comprising repeating a cycle that includes depositing the hard mask, oxidizing the metal gate film, and etching the metal oxide film.

12. The processing method according to claim 11, wherein the cycle is repeated 10 times or less.

13. Etching the metal oxide film comprises exposing the metal oxide film to one or more of a metal halide, chlorine (Cl 2 ), nitrogen trifluoride (NF 3 ), tantalum pentachloride (TaCl 5 ), tungsten pentachloride (WCl 5 ), or tungsten dioxide dichloride (WO 2 Cl 2 ), the processing method according to claim 1.

14. The processing method according to claim 1, further comprising filling the narrow feature and the wide feature with a gap-filling material that is substantially free of seams and voids.

15. The treatment method according to claim 14, wherein the gap-filling material comprises one or more of titanium nitride (TiN) and titanium oxynitride (TiON).

16. The treatment method according to claim 15, wherein the gap-filling material substantially contains no carbon (C).

17. A processing method comprising performing at least one process cycle, wherein each process cycle is: A hard mask is deposited on a metal gate film formed on a substrate surface having narrow features and wide features, wherein the narrow features have an aspect ratio of approximately 15 or more, and the wide features have an aspect ratio of 3 or less, and the hard mask is formed on the metal gate film at the top, bottom, and side walls of the wide features, and on the metal gate film on the top of the narrow features, so as to cover the metal gate film, and substantially not formed on the bottom and side walls of the narrow features, leaving the metal gate film as is, in a manner that deposits the hard mask. The process involves oxidizing the metal gate film within the narrow feature to convert a portion of the metal gate film into a metal oxide film, wherein the metal oxide film is formed as a gradient oxide layer in which the amount of metal oxide decreases from the top to the bottom of the narrow feature. This includes etching the metal oxide film from the narrow feature to leave a gradient etching profile, The aforementioned processing method further, A processing method comprising filling the narrow feature and the wide feature with a gap-filling material comprising one or more of metal nitrides, titanium nitride (TiN), and titanium oxynitride (TiON), wherein the gap-filling material is substantially free of seams and voids.

18. The processing method according to claim 17, further comprising repeating each process cycle 10 times or less.

19. The treatment method according to claim 18, wherein oxidizing the metal gate film comprises exposing the metal gate film to one or more of oxidizing plasma and oxygen radicals, and the metal oxide film comprises one or more of titanium oxynitride (TiON), tantalum oxynitride (TaON), tungsten oxynitride (WON), silicon oxynitride (SiON), and aluminum oxynitride (AlON).

20. (a) Depositing a carbon-containing hard mask onto a metal gate film formed on a substrate surface having narrow features and wide features, wherein the narrow features have an aspect ratio of 20 and a width in the range of 2 nm to 10 nm, and the wide features have an aspect ratio of 1.5 and a width in the range of 50 nm to 300 nm, and the hard mask is formed on the metal gate film at the top, bottom, and side walls of the wide features and on the metal gate film on the top of the narrow features so as to cover the metal gate film, and substantially no hard mask is formed on the bottom and side walls of the narrow features, leaving the metal gate film as is, by depositing a carbon-containing hard mask onto a metal gate film. (b) Oxidizing the metal gate film within the narrow feature to convert a portion of the metal gate film into a metal oxide film, wherein the metal oxide film is formed as a gradient oxide layer in which the amount of metal oxide decreases from the top to the bottom of the narrow feature, (c) Etching the metal oxide film from the narrow feature to leave a gradient etching profile, (d) Repeat (a) through (c) at least 10 times, (e) A processing method comprising filling the narrow feature and the wide feature with a gap-filling material containing titanium oxynitride (TiON).

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