Dry etch with etch byproduct self-cleaning

Abstract

A method includes providing a base structure within an etch chamber, the base structure including a target layer disposed on a substrate and an etch mask disposed on the target layer; dry etching the target layer using thionyl chloride within the etch chamber to obtain a treated substrate structure; and thereafter forming a plurality of features. The treated substrate structure includes a plurality of features and a plurality of openings defined by an etch mask. The method further includes removing the treated substrate structure from the etch chamber. In some embodiments, the target layer includes carbon. In some embodiments, the dry etch is performed at a temperature below zero.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to electronic device manufacturing. Specifically, embodiments of the present disclosure relate to dry etching with self-cleaning of etch byproducts. Background Art

[0002] The electronic device manufacturing apparatus may include multiple chambers, such as a process chamber and a load lock chamber. Such an electronic device manufacturing apparatus may employ a robotic device in a transfer chamber, which is configured to transport substrates between multiple chambers. In some cases, multiple substrates are transported together. The process chamber may be used in the electronic device manufacturing apparatus to perform one or more processes on the substrate, such as a deposition process and an etching process. For many processes, a gas flows into the process chamber. Electronic devices such as semiconductor devices are manufactured by performing a series of operations to form many patterned layers, and the series of operations may include deposition, oxidation, photolithography, ion implantation, etching, and the like. Summary of the invention

[0003] According to an embodiment, a method is provided. The method includes: providing a substrate structure in an etching chamber, the substrate structure including a target layer disposed on a substrate and an etching mask disposed on the target layer, and dry etching the target layer using thionyl chloride in the etching chamber to obtain a processed substrate structure. The target layer includes carbon. The processed substrate structure includes a plurality of features and a plurality of openings defined by the etching mask. The method further includes removing the processed substrate structure from the etching chamber.

[0004] According to an embodiment, a method is provided. The method includes: providing a substrate structure in an etching chamber, the substrate structure including a target layer disposed on a substrate and an etching mask disposed on the target layer, and dry etching the target layer using thionyl chloride at a temperature below zero in the etching chamber to obtain a processed substrate structure. The processed substrate structure includes a plurality of features and a plurality of openings defined by the etching mask. The method further includes removing the processed substrate structure from the etching chamber.

[0005] According to an embodiment, an etching chamber is provided. The etching chamber includes: a gas distribution plate for providing thionyl chloride; a substrate support assembly for holding a substrate structure, the substrate structure including a target layer disposed on a substrate and an etching mask disposed on the target layer; and a shower head including a plurality of gas delivery holes for dry etching the target layer using thionyl chloride to obtain a processed substrate structure. The target layer includes carbon. The processed substrate structure includes a plurality of features and a plurality of openings defined by the etching mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals indicate like elements. It should be noted that different references to "one" or "an" embodiment in the present disclosure do not necessarily mean the same embodiment, and such references mean at least one.

[0007] Figure 1 FIG. is a cross-sectional view of an etching chamber according to some embodiments.

[0008] Figure 2A FIG. is a diagram of an example method for performing dry etching to remove etch by-products using a flash evaporation process according to some embodiments.

[0009] Figure 2B FIG. is a diagram of an example method for performing dry etching with self-cleaning of etch by-products according to some embodiments.

[0010] Figure 3 FIG. is a diagram of an example method for performing dry etching with self-cleaning of etch by-products according to some embodiments.

[0011] FIG. 4A to FIG. 4B FIG. is a diagram of an example lower profile resulting from performing dry etching according to some embodiments.

[0012] Figure 5 FIG. is a flow chart of an example method for performing dry etching with self-cleaning of etch by-products according to some embodiments. DETAILED DESCRIPTION

[0013] The embodiments described herein relate to dry etching with self-cleaning of etch by-products. Electronic devices can include many different types of layers. For example, an electronic device can include a dielectric layer formed of a dielectric material, a conductive layer formed of a conductive material, and a semiconductor layer formed of a semiconductor material. Electronic device processing techniques can involve performing patterning (e.g., lithography) to produce device structures. For example, patterning can include multiple and repeated processes of deposition and etching.

[0014] In general, etching refers to a process for removing material from a base structure including a target layer formed on a substrate. For example, etching can be performed by forming a photoresist (e.g., a "soft" etch mask) on the target layer; aligning a photomask including at least one mask layer over the photoresist; exposing the base structure to ultraviolet (UV) light while each mask layer blocks a corresponding area of ​​the photoresist from exposure to the UV light; removing at least one area of ​​the photoresist by applying a solvent that develops the photoresist (i.e., a developer) to expose at least one area of ​​the target layer; and etching at least one exposed area of ​​the target layer using an etching process. After etching the at least one exposed area of ​​the target layer, the remainder of the photoresist can be removed from the target layer using an appropriate stripping chemical.

[0015] The photoresist includes a photosensitive material (e.g., a photosensitive organic material). In some implementations, the photoresist is a positive photoresist. The positive photoresist material degrades when exposed to UV light, so that each region of the photoresist exposed to UV light can be removed after the solvent is applied. In some implementations, the photoresist is a negative photoresist. Contrary to the positive photoresist, the negative photoresist material strengthens when exposed to UV light, so that each region of the photoresist not exposed to UV light can be removed after the solvent is applied.

[0016] In some implementations, an anti-reflective coating (ARC) layer may be formed on the target layer before forming the photoresist. That is, the ARC layer may be referred to as a bottom ARC layer (BARC). The ARC layer may prevent UV light reflection from occurring under the photoresist. Thus, the ARC layer may improve photoresist performance, especially as feature sizes decrease (i.e., at smaller technology nodes).

[0017] Alternatively, a hard mask may be used instead of a photoresist. For example, a hard mask may be used when the underlying material to be etched is an organic material (e.g., an organic polymer) because the etchant used to etch the underlying material will also etch the photoresist. Additionally or alternatively, a hard mask may be used when the target layer below the hard mask is formed of a material that may be damaged by the chemicals used to strip the photoresist (e.g., a low-k dielectric material). The hard mask may be formed of any suitable inorganic or organic material. The hard mask may be formed of a suitable conductive material (e.g., a metal), a dielectric material, etc. Examples of hard mask materials include silicon-based materials (e.g., silicon dioxide (SiO 2 ), silicon carbide (SiC), silicon oxynitride (SiON)), metal nitride-based materials, metal oxide-based materials, carbon-based materials, organic siloxane-based materials, and the like.

[0018] One example of etching is wet etching (i.e., liquid phase etching). During wet etching, wet etching chemicals are used to remove material from the target layer. Another example of etching is dry etching. Examples of dry etching include gas phase etching and plasma phase etching. Gas phase etching uses a gas mixture at a sufficiently high temperature to remove material from the target layer. The plasma phase ("plasma") uses plasma generated from a gas mixture at a lower temperature to remove material. Examples of plasma etching include isotropic plasma etching, ion beam milling or sputter etching, reactive-ion etching (RIE), etc.

[0019] A plasma may be generated from a process gas. The plasma may include reactive species, such as charged particles (e.g., ions) and / or neutral particles (e.g., atoms and / or free radicals). The surface of at least one exposed region of the target layer reacts with the plasma, which results in etching of these exposed portions of the target layer. The type of process gas in the gas mixture depends on the material of the target layer. The reaction between the target layer and the reactive species may produce volatile etching byproducts (e.g., smaller molecules), which may be removed by a vacuum system.

[0020] In some implementations, the process gas is delivered in a gas mixture that further includes a carrier gas. More specifically, the carrier gas may be an inert gas. For example, the carrier gas may be a rare gas, such as helium (He), argon (Ar), neon (Ne), xenon (Xe), krypton (Kr), radon (Rn), etc. In some implementations, the gas mixture may include a mixture of carrier gases (i.e., a carrier gas mixture). The carrier gas (or carrier gas mixture) may be used to dilute the gas mixture to control the etching rate or improve the etching performance.

[0021] In some implementations, the process gas is delivered without a carrier gas. For example, the process gas can be delivered via a heated gas line.

[0022] As described above, an etching mask may be disposed on a target layer, wherein the etching mask defines features to be formed from the target layer. After the dry etching pulse, etching byproducts or residues may be formed on the sidewalls of the etching mask and / or on the sidewalls of features in the target layer. More specifically, etching products may be formed in openings formed between features. The openings may be formed in at least the top surface of the target layer and / or in the bottom surface of the target layer. In some embodiments, the openings are vias. The etching byproducts may be formed at least in part due to sputtering of a mask material (e.g., silicon (Si)). For example, the etching byproducts may include a silicon oxide material (e.g., SiO 2 ). More specifically, during the bias off time during dry etching, the sputtered material may reorganize on the surface of the sidewalls of the etch mask and / or the target layer.

[0023] In the case where the opening and / or feature has a sufficiently small width (e.g., a critical dimension), the etching byproducts may cause a blockage or clogging of the opening after the etching cycle. The blockage may prevent the execution of additional dry etching processes (e.g., pulses / cycles). Typically, the etching byproducts may be removed by performing a cleaning process (also referred to as a "flash" process) after each etching pulse. The etching pulse and the flash process may form an etching cycle that is repeated until enough material is removed from the target layer (e.g., the feature reaches a target height). However, the flash process must be performed after each etching pulse, which may extend the processing time and reduce the throughput. In addition, in addition to removing the etching byproducts, the flash process may remove portions of the etching mask formed on the target layer. Therefore, the number of times the flash process can be performed is limited and is limited by the thickness of the etching mask. In addition, excessive passivation may be caused by performing dry etching at a temperature below zero (e.g., less than about 0°C). This may negatively affect the etching profile of the features formed from the target layer during dry etching.

[0024] To address these and other shortcomings, embodiments described herein may enable plasma etching with self-cleaning of etching byproducts. For example, a gas mixture used during plasma etching may include a process gas including thionyl chloride (SOCl 2 ). In some embodiments, the target layer comprises a polymer. In some embodiments, the target layer is a hard mask. In some embodiments, the target layer is a photoresist. For example, the target layer can be disposed on a dielectric layer (e.g., an oxide). In some embodiments, the target layer comprises carbon (C). For example, the target layer can include amorphous deposited carbon, spin-on carbon, CVD deposited carbon, etc.

[0025] The etch mask may be formed on the target layer. The etch mask may include a material that enables the formation of features from the target layer using dry etching with thionyl chloride. In some embodiments, the etch mask is a silicon-containing etch mask. For example, the etch mask may include silicon oxynitride (SiON). In some embodiments, the etch mask is a boron-containing etch mask. For example, the etch mask may include boron nitride (BN).

[0026] In some embodiments, the target layer may have dimensions (e.g., thickness and width) that enable the formation of high aspect ratio features. The aspect ratio represents the ratio of the feature height to the feature width (e.g., critical dimension). According to the embodiments described herein, the features may have any suitable aspect ratio. In some implementations, the high aspect ratio features may have a height to width ratio greater than or equal to about 30:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 40:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 50:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 60:1. For example, the length of the feature may be about 1000 nanometers (nm) and the width of the feature may be about 16nm (e.g., an aspect ratio of about 62.5:1).

[0027] According to embodiments described herein, features formed from the target layer may include any suitable width. In some embodiments, the width of the feature may be less than or equal to about 50 nm. In some embodiments, the width of the feature may be less than or equal to about 40 nm. In some embodiments, the width of the feature may be less than or equal to about 30 nm. In some embodiments, the width of the feature may be less than or equal to about 20 nm.

[0028] Thionyl chloride can achieve self-cleaning of etching byproducts that may form on the sidewalls of the etching mask and / or on the sidewalls of features formed from the target layer. For example, if the target layer includes H (e.g., a material including C and H), the H from the target layer can be removed to form HCl. The HCl can clean the etching byproducts and can smooth the exposed surface. Therefore, the embodiments described herein can reduce the number of flash processes that need to be performed to remove etching byproducts from the sidewalls of the etching mask and / or the target layer (e.g., eliminate the flash process).

[0029] In addition, thionyl chloride can cause chemical adsorption (i.e., chemisorption) at the surface of the sidewalls of the features formed from the target layer, which can improve the surface quality (e.g., remove surface roughness) and passivate the surface of the sidewalls of the features. For example, if the target layer includes carbon, sulfur (S) from the thionyl chloride can react with C from the target layer to form a carbon disulfide (CS)-containing carbon on the surface of the sidewalls of the features. 2 ). The presence of the passivation layer can reduce etching of the passivated surface and reduce the roughness of the passivated surface. The improved smoothness can lead to improved roundness of the surface caused by dry etching (such as dry etching performed at sub-zero temperatures). Therefore, the embodiments described herein can achieve sidewall passivation during dry etching with a thionyl chloride gas mixture without using an additional passivating gas, such as carbon sulfide (COS) or sulfur dioxide (SO 2). Thus, an improved etch profile can be achieved by performing a dry etch using the thionyl chloride gas mixture described herein.

[0030] The dry etching may be performed at any appropriate temperature. In some embodiments, the dry etching is performed at a temperature below zero degrees. As an etchant, the thionyl chloride gas mixture may counteract excessive passivation that may be caused by dry etching at a temperature below zero degrees. For example, the dry etching may be performed at a temperature less than about 0°C. As another example, the dry etching may be performed at a temperature less than or equal to about -10°C. As another example, the dry etching may be performed at a temperature less than or equal to about -20°C. As another example, the dry etching may be performed at a temperature less than or equal to about -30°C. As yet another example, the dry etching may be performed at a temperature less than or equal to about -40°C. As yet another example, the dry etching may be performed at a temperature less than or equal to about -50°C. As yet another example, the dry etching may be performed at a temperature less than or equal to about -60°C. As yet another example, the dry etching may be performed at a temperature less than or equal to about -70°C. As yet another example, the dry etching may be performed at a temperature less than or equal to about -80°C. As another example, the dry etching may be performed at a temperature less than or equal to about -90°C. If a carrier gas is included in the gas mixture with the process gas, the carrier gas may push the process gas to flow into the etching chamber at a normal speed and prevent the thionyl gas from condensing at a temperature below zero. In some embodiments, the dry etching is performed at a temperature above zero. More specifically, the dry etching may be performed at a temperature greater than about 0°C. Figures 1 to 3 Additional details regarding performing dry etching with etch byproduct self-cleaning are described.

[0031] Figure 1 1 is a cross-sectional view of an etching chamber 100 according to some embodiments. The etching chamber 100 can be used for etching processes in which a corrosive plasma environment and / or corrosive chemicals are provided. For example, the etching chamber 100 can be a chamber for a plasma etching reactor (also referred to as a plasma etcher). Examples of chamber components that can be exposed to the plasma in the etching chamber 100 are a substrate support assembly 148, an electrostatic chuck (ESC), a ring (e.g., a process kit ring or a single ring), a chamber wall, a substrate, a showerhead 130, a gas distribution plate, a liner, a liner kit, a shield, a plasma mask, a flow equalizer, a cooling substrate, a chamber viewing port, a chamber cover, a nozzle, a process kit ring, etc.

[0032] In one embodiment, the etching chamber 100 includes a chamber body 102 and a showerhead 130, which encloses an internal volume 106. The showerhead 130 may or may not include a gas distribution plate. For example, the showerhead may be a multi-piece showerhead, which includes a showerhead base and a showerhead gas distribution plate bonded to the showerhead base. Alternatively, the showerhead 130 may be replaced by a cover and a nozzle in some embodiments, or by a plurality of pie-shaped showerhead compartments and a plasma generation unit in other embodiments. The etching chamber body 102 may be made of aluminum, stainless steel, or other suitable materials. The etching chamber body 102 generally includes a sidewall 108 and a bottom 110. Any of the showerhead 130 (or cover and / or nozzle), the sidewall 108, and / or the bottom 110 may include a multi-layer plasma-resistant coating.

[0033] An outer liner 116 may be disposed adjacent to the sidewall 108 to protect the etching chamber body 102. The outer liner 116 may be a halogen-containing gas resist material such as Al 2 O 3 or Y 2 O 3 In some embodiments, the outer liner 116 may be coated with a multi-layer plasma resistant ceramic coating.

[0034] An exhaust port 126 may be defined in the etch chamber body 102 and may couple the interior volume 106 to a pump system 128. The pump system 128 may include one or more pumps and throttle valves to evacuate and regulate the pressure of the interior volume 106 of the etch chamber 100.

[0035] The showerhead 130 may be supported on the sidewall 108 of the etching chamber body 102 and / or on the top portion of the etching chamber body. The showerhead 130 (or lid) may be opened to allow access to the interior volume 106 of the etching chamber 100 and may provide a seal for the etching chamber 100 when closed. A gas distribution plate 158 may be coupled to the etching chamber 100 to provide a gas mixture including at least one process gas and / or at least one carrier gas to the interior volume 106 via the showerhead 130 or lid and nozzles. Examples of process gases that may be delivered by the gas distribution plate 158 and used to process substrates / samples in the etching chamber 100 include thionyl chloride. Examples of carrier gases (e.g., diluents) include inert gases (e.g., rare gases). The showerhead 130 includes a plurality of gas delivery holes 132 throughout the showerhead 130. The showerhead 130 may be or may include aluminum, anodized aluminum, an aluminum alloy (e.g., Al 6061), or an anodized aluminum alloy. In some embodiments, the showerhead includes a gas distribution plate coupled to the showerhead. The gas distribution plate may be, for example, Si or SiC. The gas distribution plate may further include a plurality of holes that align with the holes in the showerhead.

[0036] The substrate support assembly 148 is disposed in the interior volume 106 of the etching chamber 100, below the showerhead 130. The substrate support assembly 148 holds the base structure 144 including the substrate during processing. The substrate support assembly 148 may include an electrostatic chuck to secure the base structure 144 during processing, a metal cooling plate coupled to the electrostatic chuck, and / or one or more additional components. An internal liner may cover the periphery of the substrate support assembly 148. The internal liner may be a halogen-containing gas resist material, such as Al 2 O 3 or Y 2 O 3 In some embodiments, the substrate support assembly 148, portions of the substrate support assembly 148, and / or internal linings may be coated with a metal layer and a barrier layer.

[0037] The etching chamber 100 may be configured to perform dry etching with self-cleaning of etching byproducts, as described below with reference to Figures 2A to 5 144. In some embodiments, the target layer includes a polymer. In some embodiments, the target layer is a hard mask. In some embodiments, the target layer is a photoresist. For example, the target layer may be disposed on a dielectric layer (e.g., an oxide). In some embodiments, the target layer includes carbon. For example, the target layer may include amorphous deposited carbon, spin-on carbon, CVD deposited carbon, etc.

[0038] In some embodiments, the target layer is disposed on the dielectric layer. For example, the target layer may be disposed on a dielectric layer including an oxide material. In some embodiments, the dry etching is performed at a temperature below zero degrees. For example, the dry etching may be performed at a temperature below about 0°C. As another example, the dry etching may be performed at a temperature below about -10°C. As another example, the dry etching may be performed at a temperature below about -20°C. As another example, the dry etching may be performed at a temperature below about -30°C. As yet another example, the dry etching may be performed at a temperature below about -40°C.

[0039] For example, base structure 144 may include an etch mask stack disposed on a target layer, and the target layer may be disposed on at least one layer of the substrate. In some embodiments, the etch mask stack includes a photoresist, a BARC layer, and an etch mask. In some embodiments, the at least one layer of the substrate includes a dielectric layer (e.g., an oxide). The etch mask may include a material that enables features to be formed from the target layer during dry etching using thionyl chloride. In some embodiments, the etch mask is a silicon-containing etch mask. For example, the etch mask may include SiON. In some embodiments, the etch mask is a boron-containing etch mask. For example, the etch mask may include BN.

[0040] In some embodiments, the substrate includes a substrate layer (e.g., a dielectric layer is disposed between the target layer and the substrate layer). For example, the substrate layer may be a silicon (Si) substrate layer, a glass substrate layer, a silicon germanium (SiGe) substrate layer (e.g., a stack of alternating sublayers of Si and Ge), etc. Figures 2A to 5 Additional details regarding performing dry etching with etch byproduct self-cleaning are described.

[0041] Figure 2A FIG. 2 is a diagram of an exemplary method 200A for performing dry etching using a flash evaporation process to remove etching byproducts. Initially, a substrate structure is provided, the substrate structure including a target layer 210A and etching mask layers 220A- 1 and 220A- 2 disposed on the target layer 210A.

[0042] At step 215, a portion of the material of the target layer 210A is removed using a dry etching process (e.g., dry etching pulses / cycles). For example, the dry etching process may include at least one of plasma etching, ion beam milling, RIE, etc. More specifically, the portion of the material removed from the target layer 210A is in an area not protected by the etching mask layers 220A-1 and 220A-2. The dry etching process causes the formation of etching byproducts 230-1 at least on the sidewalls of the etching mask layers 220A-1 and 220A-2. Although not shown, the etching byproducts 230-1 may also be formed on the sidewalls of the target layer 210A. Due to the geometry of the features and openings (e.g., high aspect ratios and / or widths), the etching byproducts may cause the openings to become blocked, which may prevent further dry etching from being performed. At step 225, the etching byproducts 230-1 are removed by performing a flash evaporation process. As further shown, the flash evaporation process also removes a portion of the etching mask layers 220A-1 and 220A-2.

[0043] At step 235, another portion of the target layer 210A is removed using another dry etching process (similar to step 215). The dry etching process causes the etching byproduct 230-2 to be formed at least on the sidewalls of the etching mask layers 220A-1 and 220A-2. Although not shown, the etching byproduct 230-2 may also be formed on the sidewalls of the target layer 210A. At step 245, the etching byproduct 230-1 is removed by performing another flash evaporation process. As further shown, the flash evaporation process also removes another portion of the etching mask layers 220A-1 and 220A-2.

[0044] The process of removing portions of the target layer 210A using dry etching and then removing the resulting etch byproducts can continue until the feature is complete. However, the process of removing the etch byproducts is time consuming and may reduce throughput. In addition, the flash process may remove portions of the etch mask, which limits the number of dry etching pulses / cycles that can be performed. Therefore, as will now be described below with reference to Figure 2B As described, embodiments described herein may enable dry etching with self-cleaning of etch byproducts.

[0045] Figure 2B FIG. 2 is a diagram of an exemplary method 200B for performing dry etching with self-cleaning of etching byproducts according to some embodiments. Initially, a substrate structure is provided, the substrate structure including a target layer 210B and etching mask layers 220B- 1 and 220B- 2 disposed on the target layer 210B.

[0046] The target layer 210B may include any suitable material. In some embodiments, the target layer 210B includes a polymer. In some embodiments, the target layer 210B is a hard mask. In some embodiments, the target layer 210B is a photoresist. For example, the target layer 210B may be a hard mask disposed on a dielectric layer (e.g., an oxide). In some embodiments, the target layer 210B includes carbon. For example, the target layer 210B may include amorphous deposited carbon, spin-on carbon, CVD deposited carbon, etc.

[0047] The etch mask layers 220B-1 and 220B-2 may include any suitable material that enables features to be formed from the target layer during dry etching using thionyl chloride. In some embodiments, the etch mask layers 220B-1 and 220B-2 are silicon-containing etch mask layers. For example, the etch mask layers 220B-1 and 220B-2 may include SiON. In some embodiments, the etch mask layers 220B-1 and 220B-2 are boron-containing etch mask layers. For example, the etch mask layers 220B-1 and 220B-2 may include BN.

[0048] In some implementations, the target layer 210B may have a thickness that enables the formation of high aspect ratio features. In some embodiments, the target layer 210B has a thickness ranging from about 2 micrometers (μm) to about 20 μm. In some embodiments, the target layer 210B has a thickness ranging from about 3 μm to about 10 μm. In some embodiments, the target layer 210B has a thickness ranging from about 4 μm to about 6 μm.

[0049] In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 40: 1. In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 50: 1. In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 60: 1. For example, the length of the feature may be about 1000 nm and the width of the feature may be about 16 nm (e.g., an aspect ratio of about 62.5: 1).

[0050] According to embodiments described herein, features formed from a target layer may include any suitable width (e.g., critical dimension). In some embodiments, the width of the feature may be less than or equal to about 50 nanometers (nm). In some embodiments, the width of the feature may be less than or equal to about 40 nm. In some embodiments, the width of the feature may be less than or equal to about 30 nm. In some embodiments, the width of the feature may be less than or equal to about 20 nm.

[0051] At step 255, a portion of the target layer 210B is removed using dry etching to form a feature. Examples of dry etching include plasma etching, ion beam milling, RIE, etc. For example, the dry etching may include an appropriate number of dry etching processes (e.g., dry etching pulses / cycles). More specifically, the portion of the target layer 210B is within the area not protected by the etching mask layers 220B-1 and 220B-2.

[0052] Dry etching can utilize at least one process gas that can remove etching byproducts. More specifically, the at least one process gas can include thionyl chloride. In some embodiments, the process gas is delivered in a gas mixture that further includes at least one carrier gas. More specifically, the at least one carrier gas can include at least one inert gas. For example, the at least one carrier gas can include a rare gas (e.g., He, Ar, Ne, Xe, Kr, Rn). In some embodiments, the process gas is delivered without a carrier gas. For example, the process gas can be delivered via a heated gas line.

[0053] Thionyl chloride can achieve self-cleaning of etching byproducts that would otherwise form on the sidewalls of the etching mask and / or the target layer. For example, if the target layer includes H (e.g., a material including C and H), the H from the target layer can be removed to form HCl. HCl can clean the etching byproducts and can make the surface smooth before etching. Therefore, the embodiments described herein can reduce (e.g., eliminate) the number of flash processes that need to be performed to remove etching byproducts from the sidewalls of the etching mask and / or the target layer.

[0054] In addition, thionyl chloride can cause chemical adsorption (i.e., chemisorption) at the surface of the sidewalls of the features formed from the target layer, which can improve the surface roughness and passivate the surface of the sidewalls of the features. For example, if the target layer includes carbon, S from thionyl chloride can react with C from the target layer to form a C-containing ... 2 The improved smoothness may result in an improved roundness of the surface caused by dry etching (such as dry etching performed at a temperature below zero degrees). Thus, without using an additional passivation gas (such as COS or SO 2), sidewall passivation can be achieved during dry etching with a thionyl chloride gas mixture. Thus, an improved etch profile can be achieved by performing the dry etching using a thionyl chloride gas mixture as described herein.

[0055] The dry etching may be performed at any appropriate temperature. In some embodiments, the dry etching is performed at a temperature below zero degrees. For example, the dry etching may be performed at a temperature less than about 0°C. As another example, the dry etching may be performed at a temperature less than or equal to about -10°C. As another example, the dry etching may be performed at a temperature less than or equal to about -20°C. As another example, the dry etching may be performed at a temperature less than or equal to about -30°C. As another example, the dry etching may be performed at a temperature less than or equal to about -40°C. As another example, the dry etching may be performed at a temperature less than or equal to about -50°C. As another example, the dry etching may be performed at a temperature less than or equal to about -60°C. As another example, the dry etching may be performed at a temperature less than or equal to about -70°C. As another example, the dry etching may be performed at a temperature less than or equal to about -80°C. As another example, the dry etching may be performed at a temperature less than or equal to about -90°C. If a carrier gas is included in the gas mixture with the process gas, the carrier gas can push the process gas to flow into the etching chamber at a normal speed and prevent the thionyl gas from condensing at a temperature below zero. In some embodiments, the dry etching is performed at a temperature above zero. For example, the dry etching can be performed at a temperature greater than about 0°C.

[0056] and Figure 2A In contrast to method 200A, a reduced number of flash evaporation processes are performed to remove etching byproducts from the sidewalls of target layer 210B and / or the sidewalls of etching mask layers 220B-1 and 220B-2. In some embodiments, it is not necessary to perform a flash evaporation process to remove etching byproducts. Figure 3 Additional details regarding performing dry etching with etch byproduct self-cleaning are described.

[0057] Figure 3 300 is a diagram of an example method of performing dry etching with self-cleaning of etch byproducts according to some embodiments. As shown, a substrate structure 305 is provided. The substrate structure 305 includes a layer 310, a target layer 320 disposed on the layer 310, an etch mask 330, a BARC layer 340 disposed on the etch mask 330, and a photoresist 350 disposed on the BARC layer 340.

[0058] Layer 310 may include any suitable material. In some embodiments, layer 310 includes a dielectric material. For example, layer 310 may include an oxide (eg, a metal oxide).

[0059] The target layer 320 may include any suitable material. In some embodiments, the target layer 320 includes a polymer. In some embodiments, the target layer 320 is a hard mask. In some embodiments, the target layer 320 is a photoresist. For example, the target layer 320 may be disposed on a dielectric layer (e.g., an oxide). In some embodiments, the target layer 320 includes carbon. For example, the target layer 320 may include amorphous deposited carbon, spin-on carbon, CVD deposited carbon, etc.

[0060] In some implementations, the target layer 320 may have a thickness that enables the formation of high aspect ratio features and / or features with sufficiently small widths. In some embodiments, the target layer 320 has a thickness ranging from about 2 micrometers (μm) to about 20 μm. In some embodiments, the target layer 320 has a thickness ranging from about 3 μm to about 10 μm. In some embodiments, the target layer 320 has a thickness ranging from about 4 μm to about 6 μm.

[0061] In some implementations, the high aspect ratio features may have a height to width ratio of greater than or equal to about 30:1. In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 40:1. In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 50:1. In some embodiments, the high aspect ratio features may have a height to width ratio of greater than or equal to about 60:1. For example, the length of the feature may be about 1000 nm and the width of the feature may be about 16 nm (e.g., an aspect ratio of about 62.5:1).

[0062] The etch mask 330 may include any suitable material that enables features to be formed from the target layer during dry etching using thionyl chloride. In some embodiments, the etch mask 330 is a silicon-containing etch mask. For example, the etch mask may include SiON. In some embodiments, the etch mask 330 is a boron-containing etch mask. For example, the etch mask 330 may include BN. The BARC layer 340 may include any suitable ARC material. In some embodiments, the photoresist 350 is a positive photoresist. In some embodiments, the photoresist 350 is a negative photoresist.

[0063] A dry etch may be performed at step 360. For example, the dry etch may include plasma etching, ion beam milling, RIE, etc. The dry etch may be performed using at least one process gas. More specifically, the at least one process gas may include thionyl chloride. In some embodiments, the process gas is delivered in a gas mixture that further includes at least one carrier gas. More specifically, the at least one carrier gas may include at least one inert gas. For example, the at least one carrier gas may include a rare gas (e.g., He, Ar, Ne, Xe, Kr, Rn). In some embodiments, the process gas is delivered without a carrier gas. For example, the process gas may be delivered via a heated gas line.

[0064] The dry etching performed at step 360 results in the formation of a plurality of features 370 having sidewalls 375 and a plurality of openings 380, wherein each opening 380 separates a pair of features 370. As further shown, a portion of layer 310 is removed during the dry etching, resulting in surface 385. More specifically, features 370 are high aspect ratio features and / or have sufficiently small widths. For example, each of features 370 may have a height to width ratio greater than or equal to about 100:1.

[0065] The dry etching may be performed at any appropriate temperature. In some embodiments, the dry etching is performed at a temperature below zero degrees. For example, the dry etching may be performed at a temperature less than about 0°C. As another example, the dry etching may be performed at a temperature less than or equal to about -10°C. As another example, the dry etching may be performed at a temperature less than or equal to about -20°C. As another example, the dry etching may be performed at a temperature less than or equal to about -30°C. As another example, the dry etching may be performed at a temperature less than or equal to about -40°C. As another example, the dry etching may be performed at a temperature less than or equal to about -50°C. As another example, the dry etching may be performed at a temperature less than or equal to about -60°C. As another example, the dry etching may be performed at a temperature less than or equal to about -70°C. As another example, the dry etching may be performed at a temperature less than or equal to about -80°C. As another example, the dry etching may be performed at a temperature less than or equal to about -90°C. If a carrier gas is included in the gas mixture with the process gas, the carrier gas can push the process gas to flow into the etching chamber at a normal speed and prevent the thionyl gas from condensing at a temperature below zero. In some embodiments, the dry etching is performed at a temperature above zero. For example, the dry etching can be performed at a temperature greater than about 0°C.

[0066] The use of thionyl chloride during dry etching can achieve self-cleaning of etching byproducts that will be formed on the sidewall 375. For example, if the target layer 320 includes H (e.g., a material including C and H), the H from the target layer 320 can be removed to form HCl. HCl can clean the etching byproducts and can make the surface before etching smooth. In addition, thionyl chloride can cause chemical adsorption (i.e., chemical absorption) at the surface of the sidewall 375, which can improve the surface roughness and passivate the surface of the sidewall 375. For example, if the target layer 320 includes carbon, S from thionyl chloride can react with C of the target layer 320 to form a layer including CS on the surface of the sidewall 375. 2 The improved smoothness may result in an improved roundness of the surface 385 caused by dry etching (such as dry etching performed at a temperature below zero degrees). Thus, without using an additional passivation gas (such as COS or SO 2 ), sidewall passivation can be achieved during dry etching with a thionyl chloride gas mixture. Thus, an improved etch profile can be achieved by performing the dry etching using a thionyl chloride gas mixture as described herein. FIG. 4A to FIG. 4B Additional details regarding the improved roundness of surface 385 are described.

[0067] According to some embodiments, Figure 4A is a diagram 400A of an example bottom CD profile resulting from plasma etching performed without thionyl chloride, and Figure 4B 400B is a diagram of an example method of performing a dry etch with self-cleaning of etch byproducts using thionyl chloride. More specifically, diagram 400A shows a lower profile of a plurality of openings (e.g., vias) including opening 410A, and diagram 400B shows a lower profile of a plurality of openings including opening 410B. For example, opening 410B may be similar to the above referenced Figure 3 The opening 380 of the lower profile 390-2 described above is compared with the opening 410A. Figure 3 The described method forms the opening 410B with improved roundness and improved etch profile.

[0068] Figure 5 FIG. 5 is a flow chart of an example method 500 for performing a dry etch with self-cleaning of etch byproducts according to some embodiments. For example, the method 500 may be performed by an etching chamber, such as the one described above with reference to FIG. Figure 1 An etch chamber 100 is depicted.

[0069] At box 510, a base structure including a target layer is provided. For example, the base structure may be received by a substrate support assembly of an etching chamber for holding the base structure. The target layer may have a thickness that enables the formation of high aspect ratio features and / or features with sufficiently small widths. In some implementations, the high aspect ratio features may have a height to width ratio greater than or equal to about 30:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 40:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 50:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 60:1. For example, the length of the feature may be about 1000nm and the width of the feature may be about 16nm (e.g., an aspect ratio of about 62.5:1).

[0070] More specifically, the base structure may include an etching mask disposed on the target layer. In some embodiments, the target layer includes a polymer. In some embodiments, the target layer includes a polymer. In some embodiments, the target layer is a hard mask. In some embodiments, the target layer is a photoresist. For example, the target layer may be disposed on a dielectric layer (e.g., an oxide). In some embodiments, the target layer includes carbon. For example, the target layer may include amorphous deposited carbon, spin-on carbon, CVD deposited carbon, etc.

[0071] The etch mask may include any suitable material that enables features to be formed from the target layer during dry etching using thionyl chloride. In some embodiments, the etch mask is a silicon-containing etch mask. For example, the etch mask may include SiON. In some embodiments, the etch mask is a boron-containing etch mask. For example, the etch mask may include BN. In some embodiments, the etch mask is included in an etch mask stack, which includes an etch mask disposed on the BARC layer. In some embodiments, providing a base structure includes forming an etch mask stack on the target layer. The BARC layer may include any suitable ARC material. In some embodiments, the photoresist is a positive photoresist. In some embodiments, the photoresist 350 is a negative photoresist.

[0072] At box 520, the target layer is dry-etched using at least one process gas including thionyl chloride to obtain a processed substrate structure. In some embodiments, the at least one process gas is delivered in a gas mixture, and the gas mixture further includes at least one carrier gas. In some embodiments, the at least one process gas is delivered without a carrier gas. For example, the at least one process can be delivered via a heated gas line. Dry etching the target layer may include bringing the etching chamber to a target temperature and pressure. More specifically, one or more heating components and pumps may be used to bring the etching chamber to a target temperature and pressure. In some embodiments, the pressure of the etching chamber may be from about 0.1 mTorr to about 500 mTorr, from about 1 mTorr to about 400 mTorr, from about 5 mTorr to about 300 mTorr, from about 10 mTorr to about 200 mTorr, from about 25 mTorr to about 100 mTorr, or from about 1 mTorr to about 100 mTorr, or any sub-range or value herein. In some embodiments, the temperature of the etching chamber may be a temperature below zero. For example, dry etching may be performed at a temperature less than about 0°C. As another example, dry etching may be performed at a temperature of less than or equal to about -10°C. As another example, dry etching may be performed at a temperature of less than or equal to about -20°C. As another example, dry etching may be performed at a temperature of less than or equal to about -30°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -40°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -50°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -60°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -70°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -80°C. As yet another example, dry etching may be performed at a temperature of less than or equal to about -90°C. If a carrier gas is included in the gas mixture with the process gas, the carrier gas may propel the process gas to flow into the etching chamber at a normal speed and prevent the thionyl gas from condensing at a temperature below zero. In some embodiments, the temperature of the etching chamber may be a temperature above zero degrees (eg, greater than about 0° C.).

[0073] The dry etching target layer may further include performing a dry etching process on the substrate structure. Examples of dry etching processes include plasma etching, ion beam milling, RIE, etc. For example, the dry etching process may include a number of dry etching pulses or cycles. Performing the dry etching process may include forming a plasma from a gas mixture including thionyl chloride. In some embodiments, the gas mixture includes at least one additional process gas. In some embodiments, the gas mixture includes at least one carrier gas. More specifically, the at least one carrier gas may include at least one inert gas (e.g., at least one rare gas). In some embodiments, the at least one carrier gas includes Ar.

[0074] The total gas feed rate of the gas mixture can be any suitable total gas feed rate according to the embodiments described herein. In some embodiments, the total gas feed rate of the gas mixture is from about 50 standard cubic centimeters per minute (sccm) to about 2000 sccm, from about 100 sccm to about 1500 sccm, from about 150 sccm to about 1250 sccm, from about 200 sccm to about 1000 sccm, from about 250 sccm to about 750 sccm, or any sub-range or value herein. In some embodiments, the amount of thionyl chloride in the total gas feed flow is from about 5 mol% to about 80 mol%, from about 5 mol% to about 70 mol%, from about 5 mol% to about 60 mol%, from about 5 mol% to about 50 mol%, from about 5 mol% to about 40 mol%, from about 10 mol% to about 80 mol%, from about 10 mol% to about 70 mol%, from about 20 mol% to about 70 mol%, from about 20 mol% to about 60 mol%, from about 30 mol% to about 50 mol%, or any sub-range or value herein. In some embodiments, the amount of carrier gas in the total gas feed flow may be from about 5 mol% to about 15 mol%, from about 7.5 mol% to about 12.5 mol%, or from about 9 mol% to about 11 mol%, or any sub-range or value herein.

[0075] Performing a dry etching process may include applying a bias power to the substrate structure to achieve a bias state. Any appropriate bias power may be applied according to the embodiments described herein. In some embodiments, the bias power is from about 10 watts (W) to about 5,000 W, from about 200 W to about 2,000 W, from about 300 W to about 3,000 W, from about 400 W to about 2,500 W, from about 500 W to about 2,000 W, from about 600 W to about 1,500 W, or from about 750 W to about 1,250 W, or any sub-range or value herein. Higher bias power may result in a straighter profile (e.g., a more vertical profile on the sidewalls of the trench), along with reduced profile curvature and lower selectivity to the pattern mask. The bias power may be a time-averaged power.

[0076] The bias frequency can be any suitable frequency according to the embodiments described herein. In some embodiments, the bias frequency is from about 400 kilohertz (kHz) to about 60 megahertz (MHz), from about 400 kHz to about 40 MHz, from about 400 kHz to about 35 MHz, from about 400 kHz to about 27 MHz, from about 400 kHz to about 20 MHz, or from about 800 kHz to about 10 MHz, or any sub-range or value herein.

[0077] The bias power may be applied for any suitable time according to the embodiments described herein. In some embodiments, the bias power is applied for from about 10 μs to about 1 ms, from about 30 μs to about 1 ms, from about 50 μs to about 1 ms, from about 70 μs to about 1 ms, or from about 85 μs to about 1 ms, or any sub-range or value herein.

[0078] After stopping the bias power, performing the dry etching process may further include applying a source power to achieve a source state. Any appropriate source power may be applied according to the embodiments described herein. In some embodiments, the source power is from about 10W to about 5000W, from about 200W to about 2,000W, from about 300W to about 3,000W, from about 400W to about 2,500W, from about 500W to about 2,000W, from about 600W to about 1,500W, or from about 750W to about 1,250W, or any sub-range or value herein. The source power may be a time-averaged source power (e.g., source power multiplied by a duty cycle).

[0079] The source frequency can be any suitable frequency according to the embodiments described herein. In some embodiments, the source frequency is about 10 MHz to about 15 MHz, or about 13 MHz, or any sub-range or value herein.

[0080] The source power may be applied for any suitable time according to the embodiments described herein. In some embodiments, the source power may be applied for from about 10 μs to about 1 ms, from about 30 μs to about 1 ms, from about 50 μs to about 1 ms, from about 70 μs to about 1 ms, or from about 85 μs to about 1 ms, or any sub-range or value herein.

[0081] In some embodiments, the ratio of the first time period to the second time period is from about 1:10 to about 10:1, from about 1:9 to about 9:1, from about 1:8 to about 8:1, from about 1:7 to about 7:1, from about 1:6 to about 6:1, from about 1:5 to about 5:1, from about 1:4 to about 4:1, from about 1:3 to about 3:1, from about 1:2 to about 2:1, or about 1:1, or any sub-range or value herein.

[0082] Dry etching the target layer may include determining whether a target amount of material has been removed from the target layer. If the target amount of material has not been removed from the target layer, another dry etching cycle or pulse may be performed. If the target amount of material has been removed from the target layer, the dry etching is complete.

[0083] For example, determining whether a target amount of material has been removed from the target layer may include checking whether a target amount of material has been removed from the target layer after each dry etching cycle or pulse. Additionally or alternatively, determining whether a target amount of material has been removed from the target layer may include determining whether an amount of time that the dry etching has been performed satisfies a threshold condition (e.g., greater than or equal to a target amount of time defined by the etching recipe) based on the etching recipe. If the amount of time does not satisfy the threshold condition (e.g., the dry etching has not been performed for the target amount of time), the target amount of material may not have been removed from the target layer. If the amount of time satisfies the threshold condition (e.g., the dry etching has been performed for the target amount of time), this means that it is likely that the target amount of material has been removed from the target layer.

[0084] In some embodiments, the target layer may have dimensions (e.g., thickness and width) that enable the formation of high aspect ratio features. The aspect ratio represents the ratio of the feature height to the feature width (e.g., critical dimension). According to the embodiments described herein, the features may have any suitable aspect ratio. In some implementations, the high aspect ratio features may have a height to width ratio greater than or equal to about 30:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 40:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 50:1. In some embodiments, the high aspect ratio features may have a height to width ratio greater than or equal to about 60:1. For example, the length of the feature may be about 1000 nanometers (nm) and the width of the feature may be about 16nm (e.g., an aspect ratio of about 62.5:1).

[0085] According to embodiments described herein, features formed from the target layer may include any suitable width. In some embodiments, the width of the feature may be less than or equal to about 50 nm. In some embodiments, the width of the feature may be less than or equal to about 40 nm. In some embodiments, the width of the feature may be less than or equal to about 30 nm. In some embodiments, the width of the feature may be less than or equal to about 20 nm.

[0086] Thionyl chloride can achieve self-cleaning of etching byproducts that may form on the sidewalls of the etching mask and / or on the sidewalls of features formed from the target layer. For example, if the target layer includes H (e.g., a material including C and H), the H from the target layer can be scavenged to form HCl. The HCl can clean the etching byproducts and can smooth the exposed surface. In addition, thionyl chloride can cause chemical adsorption (i.e., chemisorption) at the surface of the sidewall of the feature formed from the target layer, which can improve the surface quality (e.g., remove surface roughness) and passivate the surface of the sidewall of the feature. For example, if the target layer is a carbon layer, the S from the thionyl chloride can react with the C from the target layer to form a C-containing CS ...HCl. 2The presence of the passivation layer can reduce etching of the passivated surface and reduce the roughness of the passivated surface. The improved smoothness can lead to improved roundness of the surface caused by dry etching (such as dry etching performed at sub-zero temperatures). Therefore, without using additional passivation gases (such as COS or SO 2 ), the dry etching performed by the thionyl chloride gas mixture at block 520 can achieve sidewall passivation. Therefore, an improved etch profile can be achieved by performing the dry etching using the thionyl chloride gas mixture at block 520.

[0087] After the dry etch is complete (e.g., after determining that a target amount of material has been removed from the target layer), the processed substrate structure may be removed at block 530. For example, the processed substrate structure may be provided to another process chamber or an etching chamber for further device processing.

[0088] The previous description sets forth many specific details, such as examples of specific systems, components, methods, etc., in order to provide a good understanding of several embodiments of the present disclosure. However, it will be apparent to those skilled in the art that at least some embodiments of the present disclosure may be practiced without these specific details. In other cases, well-known components or methods are not described in detail or presented in the form of simple block diagrams in order to avoid unnecessary confusion of the present disclosure. Therefore, the specific details set forth are merely exemplary. Specific implementations may be different from these exemplary details and are still contemplated to be within the scope of the present disclosure.

[0089] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification are not necessarily all referring to the same embodiment. Additionally, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". When the term "about" or "approximately" is used herein, this is intended to mean that the nominal value presented is accurate to within ±10%.

[0090] Although the operations of the methods are shown and described herein in a particular order, the order of operations of each method may be changed so that certain operations may be performed in a reverse order, or so that certain operations may be performed at least partially simultaneously with other operations. In another embodiment, instructions or sub-operations of different operations may be performed in an intermittent and / or alternating manner.

[0091] It should be understood that the above description is intended to be illustrative, not restrictive. After reading and understanding the above description, many other embodiments will be clear to those skilled in the art. Therefore, the scope of the present disclosure should be determined with reference to the entire scope of the equivalents authorized by the attached claims together with such claims.

Claims

1. A method, the method include: providing a base structure in an etching chamber, the base structure comprising a target layer disposed on a substrate and an etching mask disposed on the target layer, wherein the target layer comprises carbon; dry etching the target layer using thionyl chloride in the etching chamber to obtain a processed substrate structure, the processed substrate structure including a plurality of features and a plurality of openings defined by the etching mask; as well as The processed substrate structure is removed from the etching chamber. 2 . The method of claim 1 , wherein the substrate comprises a dielectric layer, and wherein the target layer is disposed directly on the dielectric layer.

3. The method of claim 1, wherein providing the base structure include: An etch mask stack including the etch mask is formed on the target layer, and wherein the etch mask stack includes the etch mask disposed on a bottom anti-reflective coating (BARC) layer. The method of claim 1 , wherein each feature of the plurality of features is a high aspect ratio feature.

5. The method of claim 4, wherein each feature of the plurality of features has an aspect ratio greater than or equal to 60:

1.

6. The method of claim 1, wherein the etch mask comprises at least one of silicon oxynitride or boron nitride. The method of claim 1 , wherein the target layer is a hard mask.

8. A method, the method comprising: include: providing a base structure in an etching chamber, the base structure comprising a target layer disposed on a substrate and an etching mask disposed on the target layer; dry etching the target layer using thionyl chloride at a sub-zero temperature in the etching chamber to obtain a processed substrate structure, the processed substrate structure including a plurality of features and a plurality of openings defined by the etching mask; as well as The processed substrate structure is removed from the etching chamber.

9. The method of claim 8, wherein the substrate comprises a dielectric layer, and wherein the target layer is disposed directly on the dielectric layer.

10. The method of claim 8, wherein providing the base structure include: An etch mask stack including the etch mask is formed on the target layer, and wherein the etch mask stack includes the etch mask disposed on a bottom anti-reflective coating (BARC) layer. The method of claim 8 , wherein each feature of the plurality of features is a high aspect ratio feature.

12. The method of claim 11, wherein each feature of the plurality of features has an aspect ratio greater than or equal to 60:

1.

13. The method of claim 8, wherein the sub-zero temperature is less than or equal to about -10°C.

14. The method of claim 8, wherein the etch mask comprises at least one of silicon oxynitride or boron nitride.

15. An etching chamber, the etching chamber include: a gas distribution plate for providing thionyl chloride; a substrate support assembly for holding a base structure comprising a target layer disposed on a substrate and an etching mask disposed on the target layer, wherein the target layer comprises carbon; and A showerhead including a plurality of gas delivery holes is used to dry etch the target layer using the thionyl chloride to obtain a processed substrate structure including a plurality of features and a plurality of openings defined by the etch mask.

16. The etch chamber of claim 15, wherein the substrate comprises a dielectric layer, and wherein the target layer is disposed directly on the dielectric layer.

17. The etch chamber of claim 15, wherein obtaining the substrate structure comprises receiving the substrate structure from the transfer robot, and wherein the substrate structure comprises an etch mask stack comprising the etch mask disposed on a bottom anti-reflective coating (BARC) layer.

18. The etch chamber of claim 15, wherein each feature of the plurality of features has an aspect ratio greater than or equal to 60:

1.

19. The etching chamber of claim 15, wherein dry etching the target layer comprises performing the dry etching at a temperature below zero degrees.

20. The etch chamber of claim 15, wherein the etch mask comprises at least one of silicon oxynitride or boron nitride.

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