Selective anisotropic metal etching

Abstract

Methods of patterning a substrate are provided. The methods include the step of modifying a surface of a metal-containing layer formed over a substrate by exposing the surface of the metal-containing layer to a plasma effluents of a chlorine-containing gas precursor and an oxygen-containing gas precursor to form a modified surface of the metal-containing layer while the substrate is positioned in a processing region of a processing chamber. The methods further include the step of directing a plasma effluents of an inert gas precursor toward the modified surface of the metal-containing layer. The plasma effluents of the inert gas precursor is directed by applying a bias to a substrate support holding the substrate. The methods further include the step of anisotropically etching the modified surface of the metal-containing layer with the plasma effluents of the inert gas precursor to form a first recess having a first sidewall in the metal-containing layer.

Description

[0001] background

[0002] field

[0003] Various embodiments of this disclosure generally relate to semiconductor devices and the manufacture of semiconductor devices. More specifically, various embodiments of this disclosure relate to methods for selectively anisotropically etching conductive materials used in semiconductor devices.

[0004] Related technical specifications

[0005] The fabrication of a semiconductor device involves forming (e.g., patterning) one or more materials having desired dimensions and spacing. For example, conductive materials can be patterned into conductive lines, such as access lines (e.g., word lines), digit lines (e.g., read lines, bit lines), conductive contacts, and conductive traces. Other feature structures can be patterned to form, such as selection devices for memory cells, memory storage elements, and other components of the semiconductor device.

[0006] As the feature size of semiconductor devices continues to shrink, it becomes increasingly difficult to pattern feature structures with desired critical dimensions. Furthermore, due to the increasing complexity of semiconductor devices, stacked structures of the material to be patterned can exhibit greater thickness (e.g., height). Additionally, as the number of patterning actions increases with the increasing complexity of semiconductor devices, the dimensions (e.g., height) or aspect ratio (defined as the ratio between the height and width of the structure) of mask materials, such as photoresist and hard mold materials, can be increased to facilitate the patterning of the desired number of feature structures in the semiconductor device. However, due to the increased height and / or aspect ratio of the mask material, the material formed through the mask can exhibit an undesirable increase in sidewall roughness, linewidth roughness (LWR), or a combination thereof. Moreover, current etching processes for conductive materials often etch the conductive material laterally, which worsens sidewall roughness and LWR. Furthermore, when the conductive material (metal) used is a grain growth metal (such as ruthenium), the grains grow within the temperature and thermal budget of the device, exhibiting an additional tendency for lateral etching along the weak grain boundaries of the metal, resulting in sidewall roughness and LWR.

[0007] Therefore, an improved method for etching conductive materials is needed. Summary of the Invention

[0008] Various embodiments of this disclosure generally relate to semiconductor devices and the manufacture of semiconductor devices. In particular, various embodiments of this disclosure relate to methods for selectively anisotropically etching conductive materials used in semiconductor devices.

[0009] In one aspect, a method for patterning a substrate is provided. The method includes the steps of: modifying the surface of a metal-containing layer formed on a substrate by exposing the surface of the metal-containing layer to a chlorine-containing gas precursor and an oxygen-containing gas precursor to form a modified surface of the metal-containing layer, the substrate being positioned in a processing region of a processing chamber. The method further includes the step of: guiding a plasma effluent of an inert gas precursor toward the modified surface of the metal-containing layer, wherein the plasma effluent of the inert gas precursor is guided by applying a bias voltage to a substrate support holding the substrate. The method further includes the step of: anisotropically etching the modified surface of the metal-containing layer using the plasma effluent of the inert gas precursor to form a first recess having a first sidewall in the metal-containing layer, wherein the plasma effluent of the inert gas precursor selectively etches the modified surface of the metal-containing layer relative to an unmodified portion.

[0010] The implementation includes one or more of the following: The inert gas precursor is argon. The metal-containing layer includes one or more of the group consisting of ruthenium (Ru), iridium (Ir), platinum (Pt), and rhodium. Anisotropic etching of the modified surface containing the metal-containing layer forms a characteristic structure including character lines within the metal-containing layer. A chlorine-containing gas precursor flows into the processing region at a flow rate from about 10 sccm to about 50 sccm, and an oxygen-containing gas precursor flows into the processing region at a flow rate from about 100 sccm to about 150 sccm. During the modification of the metal-containing surface and the anisotropic etching of the modified surface containing the metal-containing layer, the pressure within the processing region is maintained at or below about 20 millitors. The bias voltage guiding the plasma effluent of the inert gas precursor toward the modified surface containing the metal-containing layer is or below about 150 watts. The method is repeated at least one additional cycle. The temperature of the electrostatic chuck (ESC) in the processing chamber is maintained at or below about 50 degrees Celsius. Modification of the metal-containing surface is performed without etching the metal-containing surface. Before modifying the surface containing the metal layer, inert gas ions are implanted into the surface containing the metal layer. The first recess is exposed to an etchant gas mixture comprising a passivating gas and an etchant gas to remove additional metal from the metal layer. The method further includes the steps of: forming a plasma of the etchant gas mixture; passivating a first sidewall of the first recess using the plasma effluent of the passivating gas; and anisotropically etching the first recess using the plasma effluent of the etchant gas to deepen the first recess using a second sidewall in the metal layer aligned with the first sidewall. The passivating gas is selected from nitrogen (N2), sulfur dioxide (SO2), or a combination thereof. The etchant gas contains oxygen (O2) and chlorine (Cl2).

[0011] In another aspect, a method for patterning a substrate is provided. The method includes the step of exposing the surface of a metal-containing layer formed on the substrate to an etchant gas mixture comprising a passivation gas selected from N2 and SO2 and an etchant gas comprising O2 and Cl2, while the substrate is positioned in a processing region of a processing chamber. The method further includes the step of anisotropically etching the metal-containing layer using plasma from the etchant gas mixture.

[0012] Multiple implementations may include one or more of the following. The method further includes the steps of: modifying the surface of the metal-containing layer to form a modified surface by exposing the surface of the metal-containing layer to a plasma effluent containing a chlorine gas precursor and an oxygen gas precursor before exposing the surface of the metal-containing layer to the etchant gas mixture. The modified surface of the metal-containing layer is removed by anisotropically etching the metal-containing layer using the plasma of the etchant gas mixture.

[0013] In yet another aspect, a method for patterning a substrate is provided. The method includes the step of exposing the surface of a ruthenium-containing layer formed on the substrate to an etchant gas mixture, wherein the substrate is positioned in a processing region of a processing chamber. The etchant gas mixture comprises 50-200 sccm of O2; 10-100 sccm of Cl2; 100-300 sccm of argon; and 5-100 sccm of N2 or 10-30 sccm of SO2. The method further includes the step of anisotropically etching the ruthenium-containing layer using a plasma of the etchant gas mixture, including maintaining the substrate at a temperature from about 20 degrees Celsius to about 40 degrees Celsius and maintaining the plasma of the etchant gas mixture at a pressure from about 10 mTorr to about 20 mTorr.

[0014] Multiple implementations may include one or more of the following: anisotropically etching a ruthenium-containing layer to form a feature structure including a ruthenium-containing layer for character lines.

[0015] In yet another aspect, a non-transitory computer-readable medium has instructions stored on the non-transitory computer-readable medium that, when executed by a processor, cause the process to perform the operations of the above-described apparatus and / or methods. Attached Figure Description

[0016] To provide a detailed understanding of the features and structures described above in this disclosure, a more specific description of the various embodiments briefly summarized above can be obtained by referring to multiple embodiments. Some embodiments of these embodiments are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate multiple typical embodiments of this disclosure and are not intended to limit the scope of this disclosure, as this disclosure may include other equivalent embodiments.

[0017] Figure 1A cross-sectional view illustrating an example of a plasma processing chamber according to aspects of this disclosure.

[0018] Figure 2 A flowchart illustrating a method for etching a feature structure in a substrate according to aspects disclosed in this disclosure.

[0019] Figures 3A-3G This describes the various stages of the etching process according to the aspects disclosed in this disclosure.

[0020] Figure 4 A flowchart illustrating another method for etching a feature structure in a substrate according to aspects disclosed in this disclosure.

[0021] Figures 5A-5D This describes the various stages of the etching process according to the aspects disclosed in this disclosure.

[0022] Figure 6 A flowchart illustrating another method for etching a feature structure in a substrate according to aspects disclosed in this disclosure.

[0023] Figures 7A-7E This describes the various stages of the etching process according to the aspects disclosed in this disclosure.

[0024] For ease of understanding, the same reference numerals have been used as much as possible to denote common elements in the figures. It is contemplated that elements and features of one embodiment may be advantageously incorporated into several other embodiments without further description. Detailed Implementation

[0025] The following disclosure describes the etching of conductive feature structures. In the following description and... Figures 1-7E Certain specific details are set forth in this disclosure to provide a thorough understanding of the various embodiments thereof. No further details describing known structures and systems related to etching are presented in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments. Furthermore, the device descriptions in this disclosure are illustrative and should not be considered or construed as limiting the scope of the various embodiments described herein.

[0026] The numerous details, operations, dimensions, angles, and other features shown in the drawings are merely illustrative of several specific embodiments. Therefore, other embodiments may have different details, components, dimensions, angles, and features without departing from the spirit or scope of this disclosure. Furthermore, further embodiments of this disclosure may be implemented without requiring some of the details described below.

[0027] Several embodiments of this disclosure relate to methods for selective anisotropic etching of conductive materials in semiconductor devices including conductive feature structures, methods for forming conductive feature structures such as character line stacks with reduced resistance and surface roughness, and methods for forming character line stacks with reduced resistance and character line surface roughness. Despite the need for node reduction, one or more embodiments of this disclosure advantageously address the problem of resistivity reduction. In some embodiments, the resistivity of the character lines is reduced by reducing the surface roughness of the character line metal. Some embodiments of this disclosure advantageously provide improved roughness, controlled anisotropic etching, improved selectivity for hard mold materials, and improved wafer-to-wafer and intra-wafer uniformity, or one or more.

[0028] Existing known etching processes typically etch metallic materials along grain boundaries, which can result in rough sidewalls. Existing layer-by-layer atomic etching processes often lack directionality. This lack of directionality can lead to lateral etching of the vertical sidewalls, which reduces the critical dimension and degrades sidewall roughness, causing defects in structures along lengths such as character lines. Several embodiments described in this disclosure reduce the lateral etching present in known etching techniques and thus provide smooth sidewalls with reduced resistivity.

[0029] While the specific devices that can implement the embodiments described in this disclosure are not limited, it is particularly advantageous to implement multiple embodiments using devices sold by Applied Materials Inc. of Santa Clara, California. Etching systems. In addition, other available etching systems may also benefit from the various embodiments described in this disclosure.

[0030] As used in this disclosure, "substrate" means the surface of a material, or a surface or portion of a material on which a film treatment is performed during a manufacturing process. For example, depending on the application, substrate surfaces on which treatments can be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, doped amorphous silicon, polysilicon, doped polysilicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers. In addition to film treatments performed directly on the surface of the substrate itself, any of the disclosed film treatment steps may also be performed on an under-layer formed on the substrate, as disclosed more precisely below, and as indicated herein, the term "substrate surface" is intended to include this under-layer. Thus, for example, when a film / layer or a portion of a film / layer is deposited on a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0031] The substrate can be a silicon wafer, such as a 200-mm, 300-mm, or 450-mm wafer, including wafers having one or more layers of materials such as dielectric, conductive, or semi-conductive deposited on the wafer. The patterned substrate may have "feature structures" such as vias or contact holes, characterized by narrow and / or recessed openings, constrictions within the feature structure, and one or more high aspect ratios. Feature structures may be formed in one or more of the layers described above. One example of a feature structure is a hole or via in a semiconductor substrate or layer on the substrate. Another example is a trench in a substrate or layer. In some embodiments, the feature structure may have an underlying layer, such as a barrier layer or adhesion layer. Non-limiting examples of underlying layers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers.

[0032] In some embodiments, the type of substrate manufactured by implementing the disclosed embodiments may depend on the aspect ratio of the feature structures on the substrate prior to implementing the disclosed embodiments. The aspect ratio is a comparison of the depth of the feature structure to a critical dimension of the feature structure (e.g., width / diameter). In some embodiments, the feature structures on the substrate may have an aspect ratio of at least about 2:1, at least about 3:1, at least about 4:1, at least about 6:1, at least about 10:1, or higher. The feature structures may also have an opening diameter near the opening, such as an opening diameter with a linewidth between about 5 nm and 500 nm, for example, between about 25 nm and about 300 nm. In one example for a DRAM application, the feature structures have linewidths with a pitch ranging from about 10 nm to about 40 nm, wherein the linewidth ranges from about 10 nm to about 30 nm (e.g., a 24 nm linewidth with a 20 nm pitch; a 35 nm linewidth with a 30 nm pitch; or a 12 nm linewidth with a 6 nm pitch).

[0033] One or more embodiments of this disclosure generally provide structures including one or more low-resistivity feature structures formed of a film refractory metal (e.g., ruthenium), such as feature structures that can be implemented in character line structures and / or gate stacks. Some embodiments include methods for forming character line stacks. As an example, the character line structures formed according to various embodiments of this disclosure can be memory-type semiconductor devices, such as DRAM-type integrated circuits.

[0034] Figure 1This is a simplified cross-sectional view of an example of a plasma processing chamber 100 suitable for patterning material layers and forming material layers disposed on a substrate 300 within the plasma processing chamber 100. The plasma processing chamber 100 is suitable for performing etching processes as described in this disclosure. An example of a plasma processing chamber 100 adaptable to benefit from this disclosure is a product of Applied Materials, Inc., located in Santa Clara, California. Processing chamber. It is contemplated that multiple embodiments, including other processing chambers from other manufacturers, may be adapted to implement this disclosure.

[0035] The plasma processing chamber 100 includes a chamber body 105 having a processing space 101 defined therein. The chamber body 105 has sidewalls 112 and a bottom 118, which are coupled to a ground 126. The sidewalls 112 have gaskets 115 to protect the sidewalls 112 and extend the interval between maintenance cycles of the plasma processing chamber 100. The dimensions of the chamber body 105 and related components of the plasma processing chamber 100 are not limited and can be proportionally larger than the size of the substrate 300 to be processed within the dimensions of the chamber body 105 and related components of the plasma processing chamber 100. Examples of workpiece sizes, among others, include diameters of 200 mm, 250 mm, 300 mm, and 450 mm.

[0036] The chamber body 105 supports the chamber cover assembly 110 to surround the processing space 101. The chamber body 105 may be made of aluminum or other suitable materials. A substrate access port 113 is formed through the sidewall 112 of the chamber body 105 to facilitate the transfer of the substrate 300 into and out of the plasma processing chamber 100. The substrate access port 113 may be coupled to a transfer chamber and / or other chambers of the substrate processing system (not shown).

[0037] A pumping port 145 is defined in the chamber body 105 and connected to the processing space 101. A pumping device (not shown) is coupled to the processing space 101 via the pumping port 145 to vent and control the pressure of the processing space 101. The pumping device may include one or more pumps and a throttle valve.

[0038] Gas panel 160 is coupled to chamber body 105 via gas line 167 to supply process gas to process space 101. Gas panel 160 may include one or more process gas sources 161, 162, 163, 164 and may additionally include inert gases, non-reactive gases, and reactive gases if required. Examples of process gases that can be provided by gas panel 160 include, but are not limited to, oxygen-containing gases, including O2, H2O, H2O2, O3, N2O, NO2; halogen-containing gases, including Cl2, HCl, HF, F2, Br2, HCl, HBr, SF6, NF3; passivating gases, including nitrogen (N2) and sulfur dioxide (SO2); and inert gases, including argon and helium. In addition, the gases to be processed may include gases containing nitrogen, chlorine, fluorine, oxygen and hydrogen, especially gases such as BCl3, C2F4, C4F8, C4F6, CHF3, CH2F2, CH3F, NF3, NH3, CO2, SO2, CO, N2, NO2, N2O and H2.

[0039] Valve 166 controls the process gas flow from sources 161, 162, 163, and 164 via gas panel 160 and is managed by system controller 165. The gas flow supplied from gas panel 160 to chamber body 105 may include combinations of gases.

[0040] The chamber cover assembly 110 may include a nozzle 114. The nozzle 114 has one or more ports for guiding process gases from sources 161, 162, 163, 164 of the gas panel 160 into the process space 101. After the process gases are guided into the plasma processing chamber 100, the gases are energized to form plasma. An antenna 148, such as one or more sensor coils, may be provided adjacent to the plasma processing chamber 100. An antenna power supply 142 may be supplied to the antenna 148 via a matching circuit 141 to inductively couple energy, such as RF energy, to the process gases to maintain the plasma formed by the process gases in the process space 101 of the plasma processing chamber 100. Alternatively, or in addition to the antenna power supply 142, processing electrodes below and / or above the substrate 300 may be used to capacitively couple RF power to the process gases to maintain the plasma within the process space 101. The operation of the antenna power supply 142 may be controlled by a controller, such as a system controller 165, which also controls the operation of other components in the plasma processing chamber 100.

[0041] A substrate support bracket 135 is disposed in the processing space 101 to support the substrate 300 during processing. The substrate support bracket 135 may include an electrostatic chuck (ESC) 122 for holding the substrate 300 during processing. The ESC 122 uses electrostatic attraction to hold the substrate 300 to the substrate support bracket 135. The ESC 122 is powered by an RF power supply 125 integrated with matching circuitry 124. The ESC 122 includes electrodes 121 embedded within a dielectric body. The electrodes 121 are coupled to the RF power supply 125 and provide a bias voltage, which attracts plasma ions formed by the processing gas in the processing space 101 to the ESC 122 and the substrate 300 positioned on the ESC 122. During processing of the substrate 300, the RF power supply 125 may be cyclically switched on and off, or pulsed. To reduce plasma attraction on the sidewalls of the ESC 122 and extend its service life cycles, the ESC 122 has an isolator 128. In addition, the substrate support bracket 135 may have a cathode pad 136 to protect the sidewalls of the substrate support bracket 135 from plasma gas and extend the maintenance time of the plasma processing chamber 100.

[0042] Additionally, electrode 121 is coupled to power supply 150. Power supply 150 provides a clamping voltage of approximately 200 volts to approximately 2000 volts to electrode 121. By directing DC current to electrode 121 to clamp and declamp substrate 300, power supply 150 may also include a system controller for controlling the operation of electrode 121.

[0043] ESC 122 may include a heater (not shown) disposed within ESC 122 and connected to a power source for heating the substrate, while the cooling base 129 supporting ESC 122 may include conduits for circulating heat transfer fluid to maintain the temperature of ESC 122 and the substrate 300 disposed on ESC 122. ESC 122 is configured to operate within a temperature range desired by the thermal budget of the device to be manufactured on substrate 300. For example, ESC 122 is configured to maintain the substrate 300 at a temperature of about 25 degrees Celsius to about 150 degrees Celsius.

[0044] A cooling base 129 is provided to assist in controlling the temperature of the substrate 300. To mitigate process drift and time, the cooling base 129 can maintain the temperature of the substrate 300 substantially constant throughout the time the substrate 300 is located in the plasma processing chamber 100. In one embodiment, the temperature of the substrate 300 is maintained at approximately 25 degrees Celsius to approximately 150 degrees Celsius throughout the etching process.

[0045] A cover ring 130 is disposed on the ESC 122 and along the periphery of the substrate support bracket 135. The cover ring 130 is configured to confine etching gases to a desired portion of the exposed top surface of the substrate 300, while shielding the top surface of the substrate support bracket 135 from the plasma environment within the plasma processing chamber 100. A lifting rod (not shown) is selectively movable via the substrate support bracket 135 to elevate the substrate 300 above the substrate support bracket 135 to facilitate access to the substrate 300 by a transfer robot (not shown) or other suitable transfer mechanism.

[0046] The system controller 165 can be used to control the processing sequence, regulate the gas flow from the gas panel 160 to the plasma processing chamber 100, and other process parameters. When executed by the CPU, the software routines transform the CPU into a dedicated computer (controller) controlling the plasma processing chamber 100, thereby enabling processing to be performed according to this disclosure. The software routines can also be stored and / or executed by a second controller (not shown) collocated with the plasma processing chamber 100.

[0047] Figure 2 A flowchart illustrating a method 200 for etching a feature structure in a substrate according to aspects disclosed in this disclosure. Figures 3A-3G This describes the various stages of the etching process according to the aspects disclosed in this disclosure. While method 200 and... are discussed in the content regarding etching high aspect ratio feature structures in a metal-containing layer... Figure 3A-3G It should be understood that method 200 can be used to etch other feature structures in other types of substrates. Generally, method 200 is applicable to HAR contact mask opening processing and HAR line / pitch patterning (e.g., for gate lines, character lines, interconnect etching) in DRAM, flash memory, and logic devices. For example, in DRAM applications, line / pitch etching is used to form character lines.

[0048] By providing a substrate, method 200 begins at operation 210. The substrate can be... Figure 1 The substrate 300 is depicted in the image. The substrate 300 includes a film stack 302 disposed on the substrate 300. Figure 3AIn the embodiments shown, the film stack 302 includes a metal layer 310 having a hard mold layer 312 disposed on the metal layer 310. A film stack 302 without a hard mold layer 312 (i.e., containing only the metal layer 310) can also be processed according to method 200. Furthermore, the film stack 302 may include additional layers. For example, for some DRAM applications, the film stack 302 may further include cap materials, barrier layer materials, and / or photoresist materials. In some embodiments, the metal layer 310 comprises, essentially, or consists of, a grain-grown metal layer such as ruthenium, where the grain is grown at a normal thermal budget for memory manufacturing (e.g., 900 degrees Celsius for five minutes). In some embodiments, the metal layer 310 comprises one or more of ruthenium (Ru), iridium (Ir), platinum (Pt), or rhodium (Rh). In one example, the metal layer 310 comprises, is substantially composed of, or is composed of ruthenium. As used herein, the term "substantially composed of ruthenium" means that the ruthenium content of the metal layer 310 is greater than or equal to about 95%, 98%, or 99% of the metal layer 310. In one example, the metal layer 310 is a character line metal layer. The character line metal layer may comprise, is substantially composed of, or is composed of ruthenium. In some embodiments, the hard mold layer 312 comprises one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or silicon carbonitride. In one example, the hard mold layer 312 comprises or is composed of silicon nitride. In one example, the metal layer 310 is a ruthenium layer and the hard mold layer 312 is a silicon nitride hard mold layer.

[0049] exist Figure 3A In the embodiment shown, the metal layer 310 is a blanket layer and the hard mold layer 312 is a patterned hard mold having openings or apertures 314 formed therethrough. Following the deposition of the hard mold layer 312, well-known photolithography and etching processes can be used to pattern the hard mold layer 312 and form apertures 314 extending through it. Then, a substrate 300 can be provided to the processing area to continue method 200.

[0050] However, as Figure 3BAs shown in the embodiments, the metal-containing layer 310 may have at least a first feature structure 320 formed or partially formed in the metal-containing layer 310. At least one first feature structure 320 may extend from the top surface 322 of the metal-containing layer 310 toward the bottom surface 324 of the metal-containing layer 310 by a feature structure depth. At least one first feature structure 320 has a width defined by a first sidewall 326a and a second sidewall 326b. At least one first feature structure 320 may extend from the top surface 322 of the metal-containing layer 310 to the bottom surface 328 of the first feature structure 320.

[0051] In operation 220, an optional pre-amorphization process is performed to modify the exposed surface containing the metal layer 310. The pre-amorphization process may include ion doping / implantation of the exposed substrate 300. In one embodiment, beamline implantation is used to implant dopant species. In another embodiment, conformal doping techniques such as plasma doping (PLAD) may be used to implant dopant species.

[0052] In several embodiments of the pre-amorphization process where operation 220 is not performed, operation 230 may be performed directly on the metal layer 310 without pre-amorphization, as will be described in more detail below.

[0053] In some embodiments, the ion doping / implantation process 220 is performed to dope, coat, process, implant, insert, or modify specific film / surface properties at a specific location, including a bottom surface 328 having a first characteristic structure 320 to which a dopant is formed in a metal-containing layer 310, forming a doped region 332 in the metal-containing layer 310. The ion doping / implantation process utilizes incident ions to modify the film / surface properties on the metal-containing layer 310, to which a dopant is doped to form the doped region 332. Ions including desired types of atoms (e.g., inert species) can be doped into the metal-containing layer 310 at a desired concentration. Ions doped into the metal-containing layer 310 can modify the film / surface properties of the metal-containing layer 310, which can affect, improve, or change the lattice structure, crystallinity, bonding structure, or film density of the metal-containing layer 310, forming the doped region 332. Typically, operation 220 is performed to perform ion doping / planting to modify the surface containing the metal layer 310 without sputtering or substantially sputtering the metal layer 310.

[0054] Suitable ionic species for ion doping / implantation processes can be generated from inert precursor materials such as helium, argon, neon, krypton, and xenon. In one embodiment, the dopant or inert species is selected from helium, argon, neon, krypton, or combinations thereof.

[0055] In some embodiments, the doping / implantation process of the pre-amorphization process includes performing a doping / implantation process to implant ions 330 into the metal-containing layer 310 to a depth to form a doped region 332 extending below the bottom surface 328 of the first feature structure 320. Depending on the type and size of the ions and the power and bias voltage used to excite the ions 330, the ions 330 penetrate the metal-containing layer 310 to various depths. The species of ions 330 can be tailored to provide increased etch selectivity for the doped region 332. Without being theoretically limited, it is generally believed that within the doped region 332, the ion implantation during operation 220 creates damaged atomic bonds in the metal lattice structure, making the material defined by the doped region 332 easily separable along the doped region 332. In one example, the doped region 332 can be formed from approximately to approximately Approximately below the bottom surface 328 of the first feature structure 320

[0056]

[0057] Several processing parameters can be controlled during operation 220. The selection of ion dose and implantation energy can depend on the type of dopant used, the type of material used as the metal-containing layer 310, and the desired modification of the metal-containing layer 310. During operation 220, the substrate temperature can be controlled from about 5 degrees Celsius to about 80 degrees Celsius, such as from about 40 degrees Celsius to about 50 degrees Celsius. During operation 220, the overall chamber pressure can be from about 1 millitor to about 50 millitors, for example from about 10 millitors to about 30 millitors; or from about 10 millitors to about 15 millitors.

[0058] The optional pre-amorphization treatment of operation 220 can be performed in a chamber other than that of method 200. For example, the substrate 300 is positioned in a chamber other than the plasma processing chamber 100, such as an ion implantation chamber.

[0059] Method 200 continues to operation 230, wherein substrate 300 is exposed to a modification process to modify the surface of the substrate by adsorption and / or chemisorption. Substrate 300 may be positioned such as... Figure 1The substrate support bracket 135 in the plasma processing chamber 100 depicted is on the substrate support bracket. Modification processing may include contacting the metal-containing layer 310 with halide and oxygen-containing chemical components. The halide and oxygen-containing chemical components may be in the form of gases, plasma, or reactive species. Modification processing may include contacting the metal-containing layer 310 with halide and oxygen-containing gas or gas mixtures, the halide and oxygen-containing gas or gas mixtures being adsorbed onto the surface of the metal-containing layer by adsorption or chemisorption onto the metal-containing layer. Modification processing may include contacting the metal-containing layer 310 with halide and oxygen-containing plasma effluents. Oxygen-containing gas, halogen-containing gas, or mixtures of the above substances may flow into the processing region to form in-situ plasma or enter a remote plasma region to generate plasma effluents. Plasma effluents may flow into the processing region to interact with the exposed surface of the first characteristic structure 320 of the substrate 300. For example, such as... Figure 3C As shown, the plasma effluent forms a thin reactive surface layer 340 on the sidewalls 326a, 326b and the bottom surface 328. In the context of this document, "reaction" refers to a change or transformation in which a substance decomposes, combines with other substances, or exchanges components with other substances. Therefore, it should be recognized that "chemisorbing" is a specific type of reaction that refers to the taking up and chemically binding of a substance to the surface of another substance.

[0060] In some embodiments, the modification process performed in operation 230 includes exposing substrate 300 to a modification gas mixture in the presence of an energy source. The modification gas mixture includes an oxygen-containing gas, a halogen-containing gas, and optionally an inert gas. The oxygen-containing gas may be selected from O2, H2O, H2O2, O3, N2O, NO2, or combinations thereof. In one example, the oxygen-containing gas is selected from O2, O3, or combinations thereof. Without being theoretically limited, it is thought that oxygen reacts with ruthenium to form etching byproducts that can be easily pumped from the processing chamber. The halogen-containing gas may be selected from halogens, Cl2, HCl, HF, F2, Br2, HCl, HBr, SF6, NF3, or combinations thereof. In one example, the halogen-containing gas is Cl2. The inert gas may include argon, helium, xenon, krypton, nitrogen, or combinations thereof. In one example, the oxygen-containing gas is O2 and the halogen-containing gas is Cl2. Performing operation 230 causes the modification of the surface material containing the metal layer 310 to be removed or etched to preferentially exist on other surface materials on the substrate 300. Without being theoretically limited, it is thought that operation 230 forms a thin reactive surface layer 340 with a thickness that is more easily removed than the unmodified surface. For example, in one embodiment, where the metal layer is ruthenium, the plasma species Cl2 and O2 form covalent bonds with the exposed ruthenium surface (e.g., Ru → RuO2-RuO2Cl). x →RuO4+Cl2).

[0061] In some embodiments, a plasma based on a modified gas mixture can be generated during operation 230. Species generated from the plasma based on the modified gas mixture can be generated in situ by forming the plasma in a processing chamber containing the substrate, or species generated from the plasma based on the modified gas mixture can be generated remotely in a processing chamber not containing the substrate (such as a remote plasma generator) and can be supplied to the processing chamber containing the substrate. In some embodiments, the plasma can be inductively coupled plasma, capacitively coupled plasma, or microwave plasma. The power used for the inductively coupled plasma can be set from about 50 W to about 2000 W, such as about 300 W. The power can be set at a sufficiently low level to avoid direct plasma etching of the substrate.

[0062] In some embodiments, a low RF bias power of less than about 500 watts is applied to ions formed from oxygen and halogen-containing gases to bombard the substrate with low energy. The low RF bias power reduces spontaneous etching of the substrate surface by the modified gas mixture, allowing for chemisorption of the modified gas chemical composition on the exposed surfaces of the substrate. In one example, the bias RF power is maintained from about 10 watts to about 500 watts, for example from about 10 watts to about 200 watts, such as from about 50 watts to 100 watts.

[0063] In one example, during operation 230, for a 300mm substrate, oxygen-containing gas can flow into the processing area at a rate of approximately 10 sccm to approximately 200 sccm, such as from approximately 100 sccm to approximately 150 sccm. Halogen-containing gas can flow into the processing area at a rate of approximately 10 sccm to approximately 50 sccm, such as from approximately 30 sccm to approximately 50 sccm. At an RF voltage of approximately 0 volts to approximately 500 volts, the source RF power can be maintained at a rate of approximately 50 watts to approximately 2,000 watts, such as from approximately 200 watts to approximately 300 watts. At an RF voltage of approximately 0 volts to approximately 500 volts, such as from approximately 50 volts and approximately 250 volts, for example below 200 volts, the bias RF power can be maintained at a rate of approximately 10 watts to approximately 500 watts, such as from approximately 100 watts to approximately 200 watts. During operation 230, the substrate temperature can be controlled from about 5 degrees Celsius to about 80 degrees Celsius, such as from about 40 degrees Celsius to about 50 degrees Celsius. During operation 230, the overall chamber pressure can be from about 1 millitor to about 50 millitors, for example from about 10 millitors to about 30 millitors; or from about 10 millitors to about 20 millitors.

[0064] In some embodiments, decontamination may be performed after the modification treatment of operation 230. In the decontamination operation, non-surface-bound oxygen and chlorine species are removed from the treatment chamber. This can be accomplished by decontaminating and / or evacuating the treatment chamber to remove unadsorbed modified chemical compositions without removing the chemisorbed layer. Species generated in chlorine- and oxygen-based plasmas can be removed, optionally in combination with chamber decontamination and / or evacuation, by stopping the plasma and allowing remaining species to decay. Decontamination can be accomplished using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0065] In operation 240, method 200 continues, wherein substrate 300 is exposed to a removal gas, such as plasma or ion bombardment gas, to selectively etch or remove modified portions of the surface of substrate 300, such as... Figure 3D As shown in the diagram. The removed gas or ion bombardment gas can be an inert gas plasma. The inert gas is selected from argon, neon, krypton, helium, or a combination of the above. In one example, the inert gas is argon. In one example, the inert gas plasma is generated in situ by forming a plasma in a processing area containing the substrate 300. In another example, the inert gas plasma is generated remotely and can be supplied to a processing chamber containing the substrate. In some embodiments, the plasma can be an inductively coupled plasma, a capacitively coupled plasma, or a microwave plasma.

[0066] Operation 240 is performed such that removal of the modified portion from a horizontal surface, such as the bottom surface 328 of the first feature structure 320, is preferred over removal of the modified portion from a vertical surface, such as the sidewalls 326a, 326b of the first feature structure 320. In some embodiments, during operation 240, the substrate 300 is bombarded with an ion flux 350 to etch the substrate 300. The ion flux 350 provides directional energy delivery to facilitate the removal of the modified portion containing the metal layer 310. In one instance, the ion flux is anisotropic, thereby reducing the exposure of the sidewalls 326a, 326b of the first feature structure 320. The ion flux 350 bombards a horizontal surface, such as the bottom surface 328 of the first feature structure 320, as... Figure 3D As shown, the modified portion is selectively removed from the bottom surface 328 of the first feature structure 320 relative to the sidewalls 326a, 326b, extending the first feature structure 320 downward to the second bottom surface 352, as... Figure 3E As shown in the figure. In some embodiments of performing operation 220, the doped region 332 may also be selectively etched or removed during operation 240.

[0067] In one example, the ion stream 350 can be generated by any of the aforementioned inert gases using low-frequency RF power. The ion stream 350 can be one or more types of atomic or molecular inert species with low ion energy. Examples of suitable ion species include helium ions, neon ions, xenon ions, argon ions, or combinations thereof, which have low ionization potentials, allowing for a very low plasma bias to reduce the energy level of the ion stream 350. In one example, the inert gas is argon, and plasma activation generates argon ions in the processing region, which bombard and directionally etch the modified portion of the substrate 300.

[0068] During operation 240, a bias voltage is also applied to the substrate 300 to guide ions toward the horizontal surface of the substrate 300. The bias voltage can be generated using power ranging from about 50 watts to about 1500 watts, for example from about 50 watts to about 250 watts; or from about 50 watts to about 100 watts.

[0069] In one example, during operation 240, for a 300 mm substrate, argon gas can flow into the plasma reactor at a rate from about 10 sccm to about 400 sccm, for example, from about 100 sccm to 150 sccm. At an RF voltage from about 0 volts to about 500 volts, the source RF power can be maintained at a rate from about 50 watts to about 200 watts, for example, from about 100 watts to about 150 watts. At an RF voltage from about 0 volts to about 500 volts, such as from about 50 volts to about 250 volts, for example, less than 200 volts, the bias RF power can be maintained at a rate from about 50 watts to about 300 watts, for example, from about 100 watts to about 150 watts. During operation 240, the substrate temperature can be controlled from about 5 degrees Celsius to about 80 degrees Celsius, for example, from about 40 degrees Celsius to about 50 degrees Celsius. During operation 240, the overall chamber pressure can be from about or 1 millitor to about or 50 millitor, for example from about or about 10 millitor to about or 30 millitor; or from about or 10 millitor to about or 20 millitor.

[0070] While not limited to theory, it is generally believed that bombarding the metal-containing layer 310 with an ion beam causes directional energy transfer using argon to facilitate the "etching" or removal of the modified portion. The etching in operation 240 can be considered as atomic-level etching or molecular-level etching (MLE), since the removed portion is at the size scale of the molecular components in the metal film.

[0071] In some implementations, purging may be performed after the selective etching of operation 240. During the purging operation, plasma species are removed from the processing chamber. This can be accomplished by purging and / or evacuating the processing chamber to remove remaining plasma species and etching byproducts. The generated plasma species can be removed, optionally in combination with chamber purging and / or evacuation, by stopping the plasma and allowing the remaining species to decay. Purging can be performed using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0072] In some embodiments, operations 220 to 240 may be repeatedly performed or cycled in the placement cycle, followed by a modification of the etching of the metal layer to achieve the target etching depth of the metal layer. In some embodiments, operations 230 and 240 may be repeatedly performed or cycled in the modified cycle, followed by the etching of the metal layer to achieve the target etching depth containing the metal layer 310. In one example, at least one of operations 220, 230, and 240 is repeated until the top surface 370 of the substrate 300 is exposed, as shown below. Figure 3G As shown in the image.

[0073] In operation 250, an optional passivation and etching process is performed, wherein the substrate 300 is exposed to an etchant gas mixture comprising a passivation gas and an etchant gas to selectively passivate and etch additional metal from the metal-containing layer 310. Operation 250 is performed such that sidewalls 326a, 326b are passivated, while additional metal is removed from the second bottom surface 352 of the first feature structure 320 to form a second feature structure 371 having sidewalls 372a, 372b (collectively referred to as 372) while maintaining a smooth sidewall etching profile. Figure 3F As shown, the sidewalls 372a and 372b of the second feature structure are substantially aligned with the sidewalls 326a and 326b of the first feature structure 320. The passivation gas is primarily used for sidewall passivation to reduce the undercut and bowing of the metal layer 310. The passivation gas is selected from nitrogen (N2), sulfur dioxide (SO2), or combinations thereof. The etchant gas includes oxygen (O2) and chlorine (Cl2). The etchant gas may further include an inert gas. The inert gas is selected from argon, neon, krypton, helium, or combinations thereof. In one embodiment, the etchant gas mixture includes O2, Cl2, N2, and Ar. In one example, the etchant gas mixture comprises, substantially comprises, or consists of: 50-200 sccm of O2, 10-100 sccm of Cl2, 5-100 sccm of N2, and 100-300 sccm of argon. As used in this disclosure, the term "consistently composed of..." means that the composition of the etchant gas mixture is greater than or equal to about 95%, 98%, or 99% of the total etchant gas mixture. In another embodiment, the etchant gas mixture comprises O2, Cl2, SO2, and Ar. In one example, the etchant gas mixture comprises, or is substantially composed of, 50-200 sccm of O2, 10-100 sccm of Cl2, 10-30 sccm of SO2, and 100-300 sccm of argon.

[0074] The plasma is formed from an etchant gas mixture. In one example, etchant plasma is generated in situ by forming plasma in a processing area containing substrate 300. In another example, etchant gas plasma is generated remotely and can be supplied to a processing area containing substrate 300. In some embodiments, the plasma can be inductively coupled plasma, capacitively coupled plasma, or microwave plasma.

[0075] The plasma effluent of the passivation gas transforms the exposed surfaces of the first sidewall 326a and the second sidewall 326b (collectively referred to as 326) into a passivation layer 360. The formation of the passivation layer 360 enables etching of the substrate without damaging the sidewall contours of the first sidewall 326a and the second sidewall 326b. The passivation layer 360 differs from the deposited material because it is a result of a transformation of a portion of the metal-containing layer 310. Therefore, the passivation layer 360 is not deposited on the sidewalls 326a, 326b of the metal-containing layer 310; instead, the surface layer of the sidewalls 326a, 326b is consumed in the reaction to form the passivation layer 360. In an embodiment, since the passivation layer 360 is a transformation from the metal-containing layer 310, operation 250 transforms a portion of the metal-containing layer 310 along the sidewalls 326a, 326b of the first feature structure 320. Therefore, the thin surface layer containing only the metal layer 310 is converted into a passivation layer 360, limiting the thickness of the passivation layer and thus avoiding step formation between the sidewalls 326a, 326b of the first feature structure 320 and the sidewalls 372a, 372b (collectively referred to as 372) of the subsequently formed second feature structure 371 during subsequent etching. The sidewalls 372a, 372b of the second feature structure are substantially aligned with the sidewalls 326a, 326b of the first feature structure 320. In one example, the surface layer containing the metal layer 310 on the first sidewall 326a and the second sidewall 326b is approximately... to approximately Converted to a passivation layer of 360. In another instance, the passivation layer 360 is smaller than... In yet another example, the passivation layer 360 has a thickness no greater than the thickness of the native oxide of the substrate. In yet another example, where the metal layer 310 is ruthenium, the passivation layer 360 is made of approximately... to approximately

[0076] The passivation layer 360 may be an oxide or nitride containing the metal layer 310. In one embodiment, the passivation oxide can be formed by isotropically oxidizing the first feature structure 320a using an oxidizing plasma. A weak oxidizing plasma forms a passivation layer of appropriate thickness. In one embodiment, the weak oxidizing plasma may include low-partial-pressure sulfur dioxide (SO2) gas or low-partial-pressure oxygen (O2) gas. In one example, the oxidizing plasma contains less than 100 sccm of O2 or SO2, for example, from about 10 sccm to about 30 sccm of O2. In another embodiment, a nitrogen source, such as nitrogen (N2), is provided to the processing area to convert the metal-containing surface 310 of the substrate 300 on the first sidewall 326a and the second sidewall 326b into a nitride containing the metal layer 310. In one example, the nitriding plasma contains less than 100 sccm of N2, for example, from about 10 sccm to about 30 sccm of N2.

[0077] In some embodiments, the processing pressure is low during operation 250 to reduce undercut and bending of the metal-containing layer 310. In some embodiments, the processing pressure is at or below 50 mTorr (e.g., from about 10 mTorr to about 50 mTorr). In some embodiments, the processing pressure is at or below 40 mTorr (e.g., from about 10 mTorr to about 40 mTorr). In some embodiments, the processing pressure is at or below 30 mTorr (e.g., from about 10 mTorr to about 30 mTorr). In some embodiments, the processing pressure is at or below 20 mTorr (e.g., from about 10 mTorr to about 20 mTorr). In one example, a plasma comprising an etchant gas mixture of 50-200 sccm of O2, 10-100 sccm of Cl2, 10-100 sccm of N2, and 100-300 sccm of argon is maintained at or below 20 mTorr. In another such example, a plasma comprising an etchant gas mixture of 50-200 sccm of O2, 10-100 sccm of Cl2, 10-100 sccm of SO2 and 100-300 sccm of argon is maintained at or below 20 millitor pressures.

[0078] In a further embodiment, during operation 250, the substrate is maintained at a temperature from about 5 degrees Celsius to about 80 degrees Celsius, and more particularly from about 20 degrees Celsius to about 50 degrees Celsius. These low processing temperatures have been found to significantly improve the etch profile in the metal-containing layer 310 (e.g., reduce bending). In some embodiments, the substrate is maintained at temperatures from about 30 degrees Celsius and 40 degrees Celsius. In some embodiments, the substrate is maintained at temperatures from about 40 degrees Celsius and 50 degrees Celsius. In one example, during operation 250, a plasma comprising an etchant gas mixture of 50-200 sccm of O2, 10-100 sccm of Cl2, 10-100 sccm of N2, and 100-300 sccm of argon is maintained at or below 20 millitor pressures, while the substrate is maintained at about 30 degrees Celsius to about 40 degrees Celsius. In another example, during operation 250, a plasma comprising an etchant gas mixture of 50-200 sccm of O2, 10-100 sccm of Cl2, 10-100 sccm of N2 and 100-300 sccm of argon is maintained at or below 20 millitor pressures, while the substrate is heated from about 30 degrees Celsius to about 40 degrees Celsius.

[0079] In some embodiments, during operation 250, during the etching of the metal layer 310, at least one RF generator operating at 2 MHz, 60 MHz, or 162 MHz excites the etching gas mixture into plasma. The RF energy can be CW (continuous wave) or pulsed at a frequency of 10-100 kHz. For several embodiments employing two or more RF energy sources (generators), one RF generator can be pulsed (single) or multiple RF generators can be pulsed (synchronized). In one embodiment including both 2 MHz and 60 MHz, a bottom (bias) power supply and a 162 MHz top (source) power supply, the 2 MHz generator can be operated to output 0-1,000 watts in CW, in a single-pulse mode or a synchronized pulse mode, while the 60 MHz generator can be operated to output 0-3,000 watts in CW, in a single-pulse or synchronized pulse mode. In a further embodiment, both the 2 MHz and 60 MHz output power greater than 0 watts. In a further embodiment, a 162MHz source power is operated using CW, single-pulse mode, or synchronous pulse mode with a power range of 0-2500 watts.

[0080] In some implementations, the source RF power can be maintained at an RF voltage ranging from about 0 volts to about 500 volts, for example from about 1500 watts to about 2000 watts. At RF voltages ranging from about 0 volts to about 500 volts, such as from about 50 volts and about 250 volts, for example less than 200 volts, the bias RF power can be maintained at a bias RF power ranging from about 50 watts to about 300 watts, for example from about 100 watts to about 150 watts.

[0081] In some implementations, a purging process can be performed after etching in operation 250. During the purging operation, plasma species are removed from the processing chamber. This can be accomplished by purging and / or evacuating the processing chamber to remove remaining plasma species and etching byproducts. The generated plasma species can be removed, optionally in combination with chamber purging and / or evacuation, by stopping the plasma and allowing the remaining species to decay. Purging can be performed using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0082] In some embodiments, operations 220 to 250 may be repeatedly performed or cyclically executed in the implantation cycle, followed by selective etching of the metal layer, and then passivation and etching, to achieve a target etching depth of the metal layer. In one embodiment, operations 230, 240, and 250 may be repeatedly performed or cyclically executed in a modified cycle, followed by etching of the metal layer to achieve a target etching depth containing the metal layer 310. In one example, at least one of operations 220, 230, and 240 is repeated until the top surface 370 of the substrate 300 is exposed, such as... Figure 3G As shown in the image.

[0083] Figure 4 A flowchart illustrating another method 400 for etching a feature structure in a substrate according to aspects disclosed in this disclosure. Figures 5A-5C This describes the various stages of the etching process according to the aspects disclosed in this disclosure. While method 400 and... Figures 5A-5C It should be understood that method 400 can be used to etch other feature structures in other types of substrates. Generally, method 400 is applicable to HAR contact mask aperture processes and HAR line / pitch patterns (e.g., for gate lines, character lines, interconnect etching) in DRAM, flash memory, and logic devices. For example, in DRAM applications, line / pitch etching is used to form character lines.

[0084] By loading the substrate onto, for example Figure 1 In the plasma processing chamber 100 depicted, method 400 begins at operation 410. The substrate may be substrate 300. In one example, substrate 300 is positioned on a substrate support bracket, such as substrate support bracket 135, operable to control the temperature of substrate 300. Substrate 300 is as described above.

[0085] exist Figure 5A In the embodiment shown, the metal layer 310 is a blanket layer and the hard mold layer 312 is a patterned hard mold having openings or apertures 314 through it. Following the deposition of the hard mold layer 312, known photolithography and etching processes can be used to pattern the hard mold layer 312 and form the apertures 314. A substrate 300 can then be provided to the processing area to continue method 400.

[0086] In such a state Figure 5B In some embodiments shown, the metal-containing layer 310 may have at least a first recess 520 formed or partially formed in the metal-containing layer 310. In one embodiment, the metal-containing layer 310 is exposed to a plasma etching process to form the first recess 520. The plasma etching process can be any suitable plasma etching process, such as any plasma etching described in this disclosure. The first recess 520 may extend from the top surface 322 of the metal-containing layer 310 toward the bottom surface 324 of the metal-containing layer 310 by a characteristic structural depth. The first recess 520 has a width defined by a first sidewall 526a and a second sidewall 526b (collectively referred to as 526) aligned with the patterned hard mold layer 312. The first recess 520 may extend from the top surface 322 of the metal-containing layer 310 toward the bottom surface 528 of the first recess 520 by a characteristic structural depth.

[0087] Optionally, method 400 continues to operation 420, wherein substrate 300 is exposed to a modification process to modify the surface of the substrate by adsorption and / or chemisorption. Operation 420 may be performed similarly to operation 230 described in this disclosure. Modification may include contacting the metal-containing layer 310 with an effluent of halide and oxygen-containing plasma. Oxygen-containing gas, halogen-containing gas, or a mixture thereof may flow into the processing region to form in-situ plasma or into a remote plasma region to generate plasma effluent. The plasma effluent may flow into the processing region to interact with the exposed surface of the first recess 520 of substrate 300. For example, as in Figure 5B As shown, the plasma effluent forms a thin reactive surface layer 540 on the sidewalls 526a, 526b and the bottom surface 528.

[0088] In some embodiments, decontamination may be performed after the modified treatment of operation 420. In the decontamination operation, non-surface-bound oxygen and chlorine species are removed from the treatment chamber. This can be accomplished by decontaminating and / or evacuating the treatment chamber to remove unadsorbed modified chemical components without removing the chemisorbed layer. Species generated in chlorine- and oxygen-based plasmas can be removed, optionally in combination with chamber decontamination and / or evacuation, by stopping the plasma and allowing remaining species to decay. Decontamination can be performed using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0089] The method continues to operation 430. In operation 430, a passivation and etching process is performed, wherein the substrate 300 is exposed to an etchant gas mixture comprising a passivation gas and an etchant gas to selectively passivate and etch additional metal from the metal-containing layer 310 to deepen the first recess 520. Operation 430 may be performed similarly to operation 250 described in this disclosure. Performing operation 430 causes the sidewalls 526a, 526b to be passivated, while removing additional metal from the bottom surface 528 to form a second feature having sidewalls 572a, 572b.

[0090] Structure 571 simultaneously maintains a smooth sidewall etching profile. (For example...) Figure 5C As shown, the sidewalls 572a and 572b of the second feature structure are substantially aligned with the sidewalls 326a and 326b of the first feature structure 320.

[0091] In some implementations, a purging process may be performed after etching in operation 430. During the purging operation, plasma species are removed from the processing chamber. This can be accomplished by purging and / or evacuating the processing chamber to remove remaining plasma species and etching byproducts. The generated plasma species can be removed, optionally in combination with chamber purging and / or evacuation, by stopping the plasma and allowing the remaining species to decay. Purging can be performed using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0092] In some implementations, operations 420 and 430 may be repeatedly performed or cyclically in a modified loop, followed by passivation and etching to achieve a target etching depth containing the metal layer. In one example, at least one of operations 420 and 430 is repeated until the top surface 570 of the substrate 300 is exposed, such as... Figure 5D As shown in the image.

[0093] Figure 6 A flowchart illustrating another method 600 for etching a feature structure in a substrate according to aspects disclosed in this disclosure. Figures 7A-7E This describes the various stages of the etching process according to the aspects disclosed in this disclosure. While method 600 and... are discussed in the content regarding etching high aspect ratio feature structures in a metal-containing layer... Figures 7A-7E It should be understood that method 600 can be used to etch other feature structures in other types of substrates. Generally, method 600 is applicable to HAR contact mask aperture processes and HAR line / pitch patterns (e.g., for gate lines, character lines, interconnect etching) in DRAM, flash memory, and logic devices. For example, in DRAM applications, line / pitch etching is used to form character lines.

[0094] By providing the substrate described above, method 600 begins at operation 610. The substrate may be the substrate 300 described above. Figure 7A In the embodiment shown, the metal layer 310 is a blanket layer and the hard mold layer 312 is a patterned hard mold having openings or apertures 314 through it. In one embodiment, as Figure 7B As shown, the metal layer 310 may have at least a first recess 720 formed or partially formed in the metal layer 310.

[0095] At operation 620, an optional pre-amorphization process is performed to modify the exposed surface containing the metal layer 310. The pre-amorphization process can be performed similarly to operation 220.

[0096] In embodiments where the pre-amorphization process of operation 620 is not performed, at operation 630, which will be described in more detail below, the passivation process can be performed directly on the metal-containing layer 310 without pre-amorphization.

[0097] In operation 630, a passivation process is performed, wherein substrate 300 is exposed to a passivation gas to passivate the exposed surface containing metal layer 310. Operation 630 is performed such that sidewalls 726a, 726b are passivated using passivation layer 760. The passivation gas is selected from nitrogen (N2), sulfur dioxide (SO2), or combinations thereof. In one example, the passivation gas mixture comprises, is substantially composed of, or consists of 5-100 sccm of N2. As used herein, the term "substantially composed of" means that the listed passivation gas mixture comprises more than or equal to about 95%, 98%, or 99% of the total passivation gas mixture. In another embodiment, the passivation gas mixture includes SO2. In one example, the passivation gas mixture comprises, is substantially composed of, or consists of 10-30 sccm of SO2.

[0098] The plasma is formed from a passivation gas mixture. In one example, the passivation gas plasma is generated in situ by forming plasma in a processing area containing substrate 300. In another example, the passivation gas plasma is generated remotely and can be supplied to a process area containing substrate 300. In one embodiment, the plasma can be inductively coupled plasma, capacitively coupled plasma, or microwave plasma.

[0099] The plasma effluent of the passivation gas transforms the exposed surfaces of the first sidewalls 726a and 726b into a passivation layer 760. The formation of the passivation layer 760 allows for substrate etching without damaging the sidewall contours of the first and second sidewalls 726a and 726b. The passivation layer 760 differs from the deposited material because it is a result of the transformation of a portion of the metal-containing layer 310. Therefore, the passivation layer 760 is not deposited on the sidewalls 726a and 726b of the metal-containing layer 310; instead, the surface layer of the sidewalls 726a and 726b is consumed in the reaction to form the passivation layer 760. In this embodiment, as the passivation layer 760 is transformed from the metal-containing layer 310, operation 630 transforms the portion of the metal-containing layer 310 along the sidewalls 726a and 726b of the first recess 720. Therefore, the thin surface layer containing only the metal layer 310 is converted into a passivation layer 760, limiting the thickness of the passivation layer. This also prevents the formation of steps between the sidewalls 726a and 726b of the first recess 720 and the sidewalls 772a and 772b (collectively referred to as 772) of the subsequently formed second recess 771 during subsequent etching. Figure 7E As shown in the image. Figure 7EAs shown, the sidewalls 772a and 772b of the second feature structure are substantially aligned with the sidewalls 726a and 726b (collectively referred to as 726) of the first recess 720. In one example, the surface layer containing the metal layer 310 on the first sidewall 726a and the second sidewall 726b is approximately... to approximately Converted to passivation layer 760. In another instance, passivation layer 760 is smaller than... In yet another example, the passivation layer 760 has a thickness no greater than the thickness of the native oxide of the substrate. In yet another example, where the metal layer 310 is ruthenium, the passivation layer 760 has a thickness of approximately... to approximately The thickness.

[0100] The passivation layer 760 may be an oxide or nitride containing the metal layer 310. In one embodiment, the passivation oxide can be formed by isotropically oxidizing the first recess 720 using an oxidizing plasma. A weak oxidizing plasma forms a passivation layer of appropriate thickness. In one embodiment, the weak oxidizing plasma may include low-partial-pressure sulfur dioxide (SO2) gas or low-partial-pressure oxygen (O2) gas. In one example, the oxidizing plasma contains less than 100 sccm of O2 or SO2, for example, from about 10 sccm to about 30 sccm of O2. In another embodiment, a nitrogen source, such as nitrogen (N2), is provided to the processing area to convert the surface of the substrate 300 containing the metal layer 310 on the first sidewall 326a and the second sidewall 326b into a nitride containing the metal layer 310. In one example, the nitriding plasma contains less than 100 sccm of N2, for example, from about 10 sccm to about 30 sccm of N2.

[0101] In some embodiments, the processing pressure is low during operation 630 to reduce undercut and bending of the metal-containing layer 310. In some embodiments, the processing pressure is at or below 50 mTorr (e.g., from about 10 mTorr to about 50 mTorr). In some embodiments, the processing pressure is at or below 40 mTorr (e.g., from about 10 mTorr to about 40 mTorr). In some embodiments, the processing pressure is at or below 30 mTorr (e.g., from about 10 mTorr to about 30 mTorr). In some embodiments, the processing pressure is at or below 20 mTorr (e.g., from about 10 mTorr to about 20 mTorr). In one example, a plasma comprising a passivating gas of 50-200 sccm of N2 is maintained at or below 10 mTorr. In another such example, a plasma comprising a passivating gas mixture of 10-100 sccm of SO2 is maintained at or below 10 mTorr.

[0102] In several further embodiments, during operation 630, the substrate is maintained at a temperature ranging from about 5 degrees Celsius to about 80 degrees Celsius, and more particularly from about 20 degrees Celsius to about 50 degrees Celsius. These low process temperatures have been found to significantly improve the etch profile in the metal-containing layer 310 (e.g., reduce bending). In some embodiments, the substrate is maintained at temperatures ranging from about 30 degrees Celsius to 40 degrees Celsius. In some embodiments, the substrate is maintained at temperatures ranging from about 40 degrees Celsius to 50 degrees Celsius. In one example, during operation 630, a plasma comprising a passivating gas mixture of 10-100 sccm of N2 is maintained at or below 10 millitor pressures, and the substrate temperature ranges from about 30 degrees Celsius to about 40 degrees Celsius. In another example, during operation 630, a plasma comprising a passivating gas mixture of 10-100 sccm of N2 is maintained at or below 10 millitor pressures, and the substrate temperature ranges from about 30 degrees Celsius to about 40 degrees Celsius.

[0103] In some embodiments, during passivation of the metal layer 310 during operation 630, at least one RF generator operating at 2 MHz, 60 MHz, or 162 MHz excites the passivation gas mixture to become plasma. The RF energy can be CW (continuous wave) or pulsed at a frequency of 10-100 kHz. For several embodiments employing two or more RF energy sources (generators), one RF generator can be pulsed (single) or multiple RF generators can be pulsed (synchronized). In one embodiment, a generator capable of operating at 2 MHz can output 0-1,000 watts (e.g., 150 watts) in CW, single-pulse, or synchronized-pulse mode.

[0104] In some implementations, a purge can be performed after the passivation process of operation 630. During the purge operation, plasma species are removed from the processing chamber. This can be accomplished by purging and / or emptying the processing chamber to remove any remaining plasma species. The generated plasma species can be removed by stopping the plasma and continuing the nitrogen gas flow.

[0105] Method 600 continues to operation 640, wherein substrate 300 is exposed to a modification process to modify the surface of the substrate by adsorption and / or chemisorption. The modification process may include contacting the metal-containing layer 310 with halide and oxidizing chemical components. The halide and oxidizing chemical components may be in the form of gases, plasmas, or reactive species. The modification process may include contacting the metal-containing layer 310 with halide and oxygen-containing gases or gas mixtures, which are adsorbed onto the surface of the metal-containing layer by adsorption or chemisorption onto the metal-containing layer. The modification process may include contacting the metal-containing layer 310 with effluents of halide and oxygen-containing plasmas. Oxygen-containing gases, halogen-containing gases, or mixtures of the above substances may flow into the processing region to form in-situ plasma or into a remote plasma region to generate plasma effluents. The plasma effluents may flow into the processing region to interact with the exposed surface of the first recess 720 of substrate 300. For example, such as Figure 7C As shown, the plasma effluent forms a thin reactive surface layer 740 on the sidewalls 726a, 726b and the bottom surface 728. The modified process of operation 640 can be performed similarly to the modified process of operation 230.

[0106] In some embodiments, decontamination may be performed after the modified treatment of operation 640. In the decontamination operation, non-surface-bound oxygen and chlorine species are removed from the treatment chamber. This can be accomplished by decontaminating and / or evacuating the treatment chamber to remove unadsorbed modified chemical compositions without removing the chemisorbed layer. Species generated in chlorine- and oxygen-based plasmas can be removed, optionally in combination with chamber decontamination and / or evacuation, by stopping the plasma and allowing remaining species to decay. Decontamination can be accomplished using any inert gas, such as N2, Ar, Ne, He, or combinations thereof.

[0107] Method 600 continues to operation 650, wherein substrate 300 is exposed to a removal gas such as plasma or ion bombardment gas to selectively etch or remove modified portions of the surface of substrate 300, such as... Figure 7D As shown in the diagram. The removed gas or ion bombardment gas can be an inert gas plasma. The inert gas is selected from argon, neon, krypton, helium, or a combination of the above. In one example, the inert gas is argon. In one example, the inert gas plasma is generated in situ by forming plasma in a processing area containing the substrate 300. In another example, the inert gas plasma is generated remotely and can be supplied to a processing chamber containing the substrate. In some embodiments, the plasma can be an inductively coupled plasma, a capacitively coupled plasma, or a microwave plasma.

[0108] Operation 650 is performed such that removal of the modified portion from a horizontal surface, such as the bottom surface 728 of the first recess 720, is preferred over removal of the modified portion from a vertical surface, such as the sidewalls 726a, 726b of the first recess 720. In some embodiments, during operation 650, the substrate 300 is bombarded with an ion stream 750 to etch the substrate 300. The ion stream 750 provides directional energy delivery to facilitate the removal of the modified portion containing the metal layer 310. In one example, the ion stream 750 is anisotropic, thereby reducing the exposure of the passivated sidewalls 726a, 726b of the first recess 720. The ion stream 750 bombards a horizontal surface, such as the bottom surface 728 of the first recess 720, as... Figure 7D As shown, by selectively removing the modified portions from the bottom surface 728 of the first recess 720 opposite the sidewalls 726a, 726b, the first recess 720 extends downward to the second bottom surface 752, as... Figure 7E As shown in the figure. The second bottom surface 752 defines the second recess 771 along the sidewalls 772a, 772b.

[0109] In some implementations, operations 630 to 650 may be repeatedly performed or cyclically during the passivation cycle, followed by modification of the metal layer and then etching to achieve the target etch depth of the metal layer. In one example, operations 630, 640, and 650 are repeated until the top surface of the substrate 300 is exposed. In one example, operations 630, 640, and 650 are repeated twenty to thirty times.

[0110] Multiple implementations may include one or more of the following potential advantages. Despite the need to shrink nodes, one or more implementations of this disclosure advantageously address the problem of resistivity reduction. In some implementations, the resistivity of the character line is reduced by decreasing the surface roughness of the character line metal. Some implementations of this disclosure advantageously provide improved roughness, controlled anisotropic etching, improved selectivity for hard mold materials, and one or more improvements in wafer-to-wafer and intra-wafer uniformity. Furthermore, due to the reduced surface roughness, the choice of character line metal material is not limited by the grain growth characteristics of the metal.

[0111] The various embodiments and all functional operations described herein may be practiced in digital electronic circuits, or in computer software, firmware, or hardware (including the structural means disclosed herein and their structural equivalents or combinations thereof). The various embodiments described herein may be practiced as one or more non-transitory computer program products, i.e., one or more computer programs tangibly embodied in a machine-readable storage device for performing or controlling the operation of a data processing device, such as a programmable processor, computer, or multiprocessor.

[0112] The processing and logic flows described herein can be executed by one or more programmable processors, which execute one or more computer programs to perform functions by manipulating input data and generating output. Processing and logic flows can also be executed by a device, and the device can also be implemented as a special-purpose logic circuit, such as an FPGA (Field-Effect Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0113] The term "data processing device" encompasses all devices, apparatuses, and machines used for processing data, including, for example, programmable processors, computers, or multiprocessor systems. In addition to hardware, the device may include code that creates the execution environment for the computer program in question, such as code defining the processor solid, protocol stack, database management system, operating system, or a combination of one or more of the foregoing. Processors suitable for executing computer programs include, for example, both general-purpose and special-purpose microprocessors, and any one or more processors of any kind of digital computer.

[0114] Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks or removable disks; magneto-optical disks; and CD ROMs and DVD-ROMs. Processors and memory may be supplemented by or incorporated into special-purpose logic circuitry.

[0115] When describing elements of this disclosure or exemplary aspects or embodiments thereof, the articles “a” and “an” are intended to indicate that there are one or more components.

[0116] The terms “comprising,” “including,” and “having” are intended to include and indicate additional elements beyond those listed.

[0117] Despite the foregoing multiple embodiments of this disclosure, other and further embodiments of this disclosure are contemplated without departing from the basic scope of this disclosure, and the scope of this disclosure is defined by the appended claims.

Claims

1. A method for patterning a substrate, comprising the following steps: During the pre-amorphization process, the initial surface containing the metal layer is exposed to ion-doped implantation using plasma doping (PLAD) technology to generate the surface containing the metal layer; then The surface of the metal-containing layer formed on a substrate positioned in the processing area of ​​a processing chamber is modified by the following steps: exposing the surface of the metal-containing layer to a chlorine-containing gas precursor and an oxygen-containing gas precursor to form the modified surface of the metal-containing layer; The plasma effluent of the inert gas precursor is guided toward the modified surface containing the metal layer, wherein the plasma effluent of the inert gas precursor is guided by applying a bias voltage to a substrate support holding the substrate. The plasma effluent of the inert gas precursor is used to anisotropically etch the modified surface of the metal-containing layer to form a first recess, the first recess having a first sidewall in the metal-containing layer, wherein the plasma effluent of the inert gas precursor selectively etches the modified surface of the metal-containing layer relative to the unmodified portion. and The first recess is exposed to an etchant gas mixture comprising passivating gas and etchant gas to remove additional metal from the metal-containing layer.

2. The method of claim 1, wherein the inert gas precursor is argon.

3. The method of claim 1, wherein the metal-containing layer comprises ruthenium.

4. The method of claim 1, wherein the step of anisotropically etching the modified surface containing the metal layer forms a feature structure containing the metal layer of character lines.

5. The method of claim 1, wherein the chlorine-containing gas precursor flows into the processing area at a flow rate of 10 sccm to 50 sccm and the oxygen-containing gas precursor flows into the processing area at a flow rate of 100 sccm to 150 sccm.

6. The method of claim 1, wherein when the surface containing the metal layer is modified and the modified surface containing the metal layer is etched anisotropically, the pressure in the processing area is maintained at or below 20 millitors.

7. The method of claim 1, wherein the bias voltage guiding the plasma effluent of the inert gas precursor toward the modified surface containing the metal layer is or less than 150 watts.

8. The method of claim 1, further comprising repeating the method by at least one additional loop.

9. The method of claim 1, wherein the temperature of the processing chamber is maintained at or below 50 degrees Celsius.

10. The method of claim 1, wherein the modification of the surface containing the metal layer is performed without etching the surface containing the metal layer.

11. The method of claim 1, further comprising the following steps: The plasma that forms the etchant gas mixture; The first sidewall of the first recess is passivated using the plasma effluent of the passivating gas; and The first recess is anisotropically etched using the plasma effluent of the etchant gas to deepen the first recess using the second sidewall in the metal-containing layer aligned with the first sidewall.

12. The method of claim 11, wherein the passivating gas is selected from nitrogen (N2), sulfur dioxide (SO2), or a combination of nitrogen (N2) and sulfur dioxide (SO2).

13. The method of claim 12, wherein the etchant gas comprises oxygen (O2) and chlorine (Cl2).

14. A method for patterning a substrate, comprising the following steps: During the pre-amorphization process, the initial surface of the ruthenium-containing layer is exposed to ion-doped implantation using plasma doping (PLAD) technology to generate the surface of the ruthenium-containing layer; then The surface of the ruthenium-containing layer formed on the substrate is exposed to an etchant gas mixture, the substrate being positioned in a processing region of a processing chamber, the etchant gas mixture comprising a passivation gas selected from N2 and SO2 and an etchant gas containing O2 and Cl2; and The ruthenium-containing layer is etched anisotropically using plasma from the etchant gas mixture.

15. The method of claim 14, further comprising the following steps: Before exposing the surface of the ruthenium-containing layer to the etchant gas mixture, the surface of the ruthenium-containing layer is modified by exposing the surface of the ruthenium-containing layer to the plasma effluent of the chlorine-containing gas precursor and the oxygen-containing gas precursor to form a modified surface of the ruthenium-containing layer.

16. The method of claim 15, wherein the step of anisotropically etching the ruthenium-containing layer using the plasma of the etchant gas mixture removes the modified surface of the ruthenium-containing layer.

17. A method for patterning a substrate, comprising the following steps: During the pre-amorphization process, the initial surface of the ruthenium-containing layer is exposed to ion-doped implantation using plasma doping (PLAD) technology to generate the surface of the ruthenium-containing layer; then The surface of the ruthenium-containing layer formed on the substrate is exposed to an etchant gas mixture, the substrate being positioned in a processing region of a processing chamber, the etchant gas mixture comprising: O2 with flow rates from 50 sccm to 200 sccm; Cl2 with flow rates from 10 sccm to 100 sccm; Argon with flow rates from 100 sccm to 300 sccm; and N2 with a flow rate from 5 sccm to 100 sccm or SO2 with a flow rate from 10 sccm to 30 sccm; and The process of anisotropically etching the ruthenium-containing layer using a plasma of the etchant gas mixture to form a recess with a first sidewall in the ruthenium-containing layer comprises the following steps: Maintain the substrate at a temperature from 20 degrees Celsius to 40 degrees Celsius; and The plasma, maintaining the etchant gas mixture, is kept at a pressure ranging from 10 mTorr to 20 mTorr; and The recess is exposed to an etchant gas mixture comprising passivating gas and etchant gas to remove additional metal from the ruthenium-containing layer.

18. The method of claim 17, wherein the step of anisotropically etching the ruthenium-containing layer forms a feature structure comprising a ruthenium-containing layer with character lines.

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