Metal introduction in hard mask for high aspect ratio device patterning

Abstract

A method for patterning a boron-containing hard mask includes patterning an oxide hard mask formed on a boron-containing hard mask; and patterning the boron-containing hard mask using the patterned oxide hard mask, in which the oxide hard mask comprises silicon oxide (SiO2), the boron-containing hard mask is doped with one or more metal elements, and the patterning of the boron-containing hard mask comprises etching the boron-containing hard mask through the opening of the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr) and oxygen (O2).

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Application Serial No. 63 / 468,661, filed May 24, 2023, which is incorporated herein by reference in its entirety.

[0002] The embodiments described herein generally relate to semiconductor device fabrication, and more specifically, to hard masks for patterning high aspect ratio structures and methods thereof. Background Technology

[0003] The semiconductor manufacturing industry continues to address the challenges of reducing node-to-node critical dimension (CD) and pitch while increasing aspect ratio. Etching high aspect ratio structures is a critical process in dynamic random access memory (DRAM) devices and three-dimensional (3D) NAND devices, where low etch variability and defects must be maintained to avoid degradation caused by vias and bottom distortion. Etching high aspect ratio device structures typically uses a hard mask for etching the device die and an oxide mask for etching the hard mask. However, defects in the hard mask openings are transferred to the device die and cause device degradation.

[0004] Therefore, there is a need for improved hard masks and their manufacturing methods for patterning high aspect ratio structures. Summary of the Invention

[0005] Embodiments of this disclosure provide a method for patterning a boron-containing hard mask. This method includes patterning an oxide hard mask formed on the boron-containing hard mask; and using this patterned oxide hard mask to pattern the boron-containing hard mask, wherein the oxide hard mask comprises silicon oxide (SiO2), the boron-containing hard mask is doped with one or more metal elements, and the patterning of the boron-containing hard mask comprises etching the boron-containing hard mask through openings in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), and oxygen (O2).

[0006] Embodiments of this disclosure provide a method for patterning a boron-containing hard mask. This method includes patterning an oxide hard mask formed on the boron-containing hard mask; and using this patterned oxide hard mask to pattern the boron-containing hard mask, wherein the oxide hard mask comprises silicon oxide (SiO2), and the patterning of the boron-containing hard mask comprises etching the boron-containing hard mask through openings in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), oxygen (O2), and a metal etchant.

[0007] Embodiments of this disclosure provide a method for patterning a boron-containing hard mask. This method includes patterning an oxide hard mask formed on the boron-containing hard mask; and using this patterned oxide hard mask to pattern the boron-containing hard mask, wherein the oxide hard mask comprises silicon oxide (SiO2), the boron-containing hard mask is doped with one or more metal elements, and the patterning of the boron-containing hard mask includes etching the boron-containing hard mask through openings in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), oxygen (O2), and a metal etchant. Attached Figure Description

[0008] To achieve and to fully understand the features described above in the embodiments herein, a more detailed description of the present disclosure, which has been briefly summarized above, can be obtained by referring to the examples shown in the accompanying drawings.

[0009] Figure 1 This is a cross-sectional view of a processing chamber according to one embodiment.

[0010] Figure 2 A flowchart of a patterning process according to one embodiment is described.

[0011] Figure 3A , Figure 3B , Figure 3C ,and Figure 3D According to one implementation method Figure 2 The image depicts a cross-sectional view of the structure formed during the patterning process.

[0012] To facilitate understanding of the embodiments, the same reference numerals are used to denote common elements in the drawings, where possible. It is considered that elements and features of one embodiment may be advantageously combined in other embodiments without further explanation.

[0013] However, it should be noted that the accompanying drawings are merely illustrative examples and should therefore not be considered as limiting the scope of this disclosure, as this disclosure may allow other equally effective implementations. Detailed Implementation

[0014] In the embodiments described herein, a boron-containing hard mask and a method thereof for patterning high aspect ratio devices, such as dynamic random access memory (DRAM) capacitors and 3D NAND devices, are provided. In high aspect ratio device patterning, defects in the hard mask are transferred to the device die, leading to device degradation. To reduce such defects in the hard mask, the boron-containing hard mask according to the described embodiments is doped with a metal element, which increases the etch selectivity of the oxide hard mask used to pattern the boron-containing hard mask and increases the passivation of the sidewalls within the openings in the patterned boron-containing hard mask. As a result, the local critical dimension uniformity (LCDU) of the openings in the patterned boron-containing hard mask is improved, and the etch variability in high aspect ratio device patterning is reduced.

[0015] Figure 1 This is a cross-sectional view of an example of an inductively coupled plasma (ICP) etching chamber 100 suitable for performing etching processes. Suitable ICP etching chambers that can be used with the methods disclosed herein include inductively coupled plasma reactive ion etching (ICP-RIE) chambers, such as the CENTRIS® SYM3™ etching chamber available from Applied Materials, Inc., Santa Clara, California. Although an ICP etching chamber 100 including several features capable of achieving excellent etching performance is shown, other ICP etching chambers are contemplated that may be suitable for benefiting from one or more of the inventive features disclosed herein.

[0016] ICP etching chamber 100 includes a chamber body 102 and a cover 104 surrounding an internal volume 106. The chamber body 102 is typically made of aluminum, stainless steel, or other suitable material. The chamber body 102 generally includes sidewalls 108 and a bottom 110. A substrate support base inlet / outlet (not shown) is generally defined in the sidewall 108 and may be sealed by a slit valve to allow the substrate W to enter and exit the ICP etching chamber 100. An exhaust port 112 is defined in the chamber body 102 and couples the internal volume 106 to a vacuum pump system 114. The vacuum pump system 114 generally includes one or more pumps and throttle valves for evacuating and regulating the pressure within the internal volume 106 of the ICP etching chamber 100.

[0017] The cover 104 is securely supported on the side wall 108 of the chamber body 102. The cover 104 can be opened to allow access to the internal volume 106 of the ICP etching chamber 100. The cover 104 includes a window 116 that facilitates optical process monitoring. In one embodiment, the window 116 is made of quartz or other suitable material that allows signals used by an optical monitoring system 118 mounted outside the ICP etching chamber 100 to be transmitted.

[0018] The optical monitoring system 118 is positioned to observe, through window 116, at least one of the internal volume 106 of the chamber body 102 and / or the substrate W positioned on the substrate support base assembly 120. In one embodiment, the optical monitoring system 118 is coupled to the cover 104 and facilitates the integration of a deposition process that uses optical metrology to provide information enabling process adjustments to compensate for inconsistencies in substrate pattern features (such as thickness and the like) and to provide process status monitoring (such as plasma monitoring, temperature monitoring, and the like) as needed. One optical monitoring system suitable for benefiting from this disclosure is the EyeD® full-spectrum interferometry module available from Applied Materials, Inc., Santa Clara, California.

[0019] Gas panel 122 is coupled to ICP etching chamber 100 to supply process and / or cleaning gases to internal volume 106. Figure 1 In the illustrated example, inlets 124, 126 are disposed in cover 104 to allow gas to be delivered from gas panel 122 to the internal volume 106 of ICP etching chamber 100. In one embodiment, gas panel 122 is adapted to provide fluorination process gas through inlets 124, 126 and to provide this gas to the internal volume 106 of ICP etching chamber 100.

[0020] The shower head assembly 128 is coupled to the inner surface 130 of the cover 104. The shower head assembly 128 includes a plurality of holes that allow gas to flow from the inlets 124, 126 through the shower head assembly 128 into the internal volume 106 of the ICP etching chamber 100 in a predetermined distribution across the surface of the substrate W treated in the ICP etching chamber 100.

[0021] A remote plasma source 132 may be connected to the gas panel 122 to facilitate the dissociation of the gas mixture from the remote plasma before it enters the internal volume 106 for processing. A radio frequency (RF) source power 134 is coupled to the shower head assembly 128 via a matching network 136. The RF source power 134 is typically capable of generating up to approximately 3000 W of power at a tunable frequency ranging from approximately 50 kHz to approximately 200 MHz.

[0022] The shower head assembly 128 also includes a region that transmits optical metering signals. The optical transmission region or channel 138 is adapted to allow the optical monitoring system 118 to observe the internal volume 106 and / or the substrate W positioned on the substrate support base assembly 120. The channel 138 may be a material, a hole, or multiple holes formed or disposed in the shower head assembly 128, substantially transmitting wavelengths of energy generated by the optical monitoring system 118 and reflected back to the optical monitoring system.

[0023] In one embodiment, the showerhead assembly 128 is configured with multiple regions that allow for individual control of the gas flowing into the internal volume 106 of the ICP etching chamber 100. Figure 1 In the example shown, the shower head assembly 128 has an inner region 140 and an outer region 142, which are individually connected to the gas panel 122 through separate inlets 124, 126.

[0024] The substrate support base assembly 120 is disposed within the internal volume 106 of the ICP etching chamber 100, below the showerhead assembly 128. The substrate support base assembly 120 holds the substrate W during processing. The substrate support base assembly 120 generally includes a plurality of lifting rods (not shown) disposed therethrough, configured to lift the substrate W from the substrate support base assembly 120 and facilitate exchange of the substrate W with a robot (not shown) in a conventional manner. An inner liner 144 tightly surrounds the periphery of the substrate support base assembly 120.

[0025] In one embodiment, the substrate support base assembly 120 includes a mounting plate 146, a base 148, and an electrostatic chuck 150. The mounting plate 146 is coupled to the bottom 110 of the chamber body 102 and includes channels for routing utilities such as fluid, power lines, sensor leads, and other utilities to the base 148 and the electrostatic chuck 150. The electrostatic chuck 150 includes at least one clamping electrode 152 for holding the substrate W below the shower head assembly 128. The electrostatic chuck 150 is driven by a clamping power supply 154 to generate an electrostatic force that holds the substrate W to the chuck surface, as is conventional. Alternatively, the substrate W can be held to the substrate support base assembly 120 by clamping, vacuum, or gravity.

[0026] At least one of the base 148 or the electrostatic chuck 150 may include at least one optional embedded heater 156, at least one optional embedded isolator 158, and a plurality of conduits 160, 162 to control the lateral temperature distribution of the substrate support base assembly 120. The conduits 160, 162 are fluidly coupled to a fluid source 164 through which temperature-regulating fluid is circulated. The heater 156 is regulated by a power supply 166. The conduits 160, 162 and the heater 156 are used to control the temperature of the base 148, thereby heating and / or cooling the electrostatic chuck 150, and ultimately controlling the temperature distribution of the substrate W disposed thereon. A plurality of temperature sensors 168, 170 may be used to monitor the temperature of the electrostatic chuck 150 and the base 148. The electrostatic chuck 150 may also include a plurality of gas channels (not shown), such as grooves, formed in the substrate support base support surface of the electrostatic chuck 150, and fluidly coupled to a source of heat transfer (or back-side) gas (such as helium (He)). During operation, back gas is supplied to the gas channel under controlled pressure to enhance heat transfer between the electrostatic chuck 150 and the substrate W.

[0027] In one embodiment, the substrate support base assembly 120 is configured as a cathode and includes clamping electrodes 152 coupled to a plurality of RF bias power supplies 172, 174. The RF bias power supplies 172, 174 are coupled between the clamping electrodes 152 disposed in the substrate support base assembly 120 and another electrode (such as a showerhead assembly 128 or a cover 104 of the chamber body 102). The RF bias power excites and sustains a plasma discharge formed by a gas disposed in a processing region of the chamber body 102.

[0028] exist Figure 1 In the illustrated example, dual RF bias power supplies 172 and 174 are coupled to clamping electrodes 152 disposed in the substrate support base assembly 120 via matching circuit 176. Signals generated by the RF bias power supplies 172 and 174 are fed into the substrate support base assembly 120 via matching circuit 176 through a single feed to ionize the gas mixture provided in the ICP etching chamber 100, thereby providing the ion energy necessary for deposition or other plasma-enhanced processes. The RF bias power supplies 172 and 174 are generally capable of generating RF signals with frequencies ranging from approximately 50 kHz to approximately 200 MHz and power between approximately 0 watts and approximately 5000 watts. An additional bias power supply 178 may be coupled to the clamping electrodes 152 to control plasma characteristics.

[0029] In one operating mode, the substrate W is placed on the substrate support base assembly 120 within the ICP etching chamber 100. Process gases and / or gas mixtures are introduced into the chamber body 102 from the gas panel 122 via the showerhead assembly 128. The vacuum pump system 114 maintains pressure inside the chamber body 102 while removing deposition byproducts.

[0030] Controller 180 is coupled to ICP etching chamber 100 to control the operation of the ICP etching chamber. Controller 180 includes a central processing unit (CPU) 182, memory 184, and support circuitry 186 for controlling the process sequence and regulating the gas flow from gas panel 122. CPU 182 can be any type of general-purpose computer processor that can be used in an industrial environment. Software routines can be stored in memory 184, such as random access memory, read-only memory, floppy disk drive, hard disk drive, or other forms of digital storage. Support circuitry 256 is conventionally coupled to CPU 182 and may include cache, frequency circuitry, input / output systems, power supplies, and the like. Bidirectional communication between controller 180 and various components of ICP etching chamber 100 is operated via a plurality of signal cables.

[0031] Figure 2 A process flow diagram is depicted for a method 200 of forming a semiconductor structure 300 according to one or more embodiments of the present disclosure, the semiconductor structure being formed into a high aspect ratio structure, such as a DRAM capacitor or a 3D NAND element. Figure 3A , Figure 3B , Figure 3C ,and Figure 3D This is a cross-sectional view of a portion of the semiconductor structure 300 corresponding to various states of method 200. It should be understood that... Figure 3A , Figure 3B , Figure 3C ,and Figure 3D Only a partial schematic diagram of the semiconductor structure 300 is shown, and the semiconductor structure 300 may contain any number of transistor portions and additional materials as shown in the figure. It should also be noted that, although... Figure 2 The methods shown are described sequentially, but other process sequences including one or more operations that have been omitted and / or added and / or rearranged in another desired order fall within the scope of the embodiments of this disclosure provided herein.

[0032] like Figure 3AAs shown, the semiconductor structure 300 includes a film stack 302 formed on a substrate (not shown). The film stack 302 may include a stack mold 302A of alternating silicon oxide (SiO2) layers and silicon nitride (Si3N4) layers, and a dielectric layer 302B formed on the stack mold 302A. The stack mold 302A may have a thickness between about 5000 Å and about 20 μm, for example, about 3 μm. In some embodiments, the stack mold 302A may be alternating silicon (Si) layers and silicon oxide (SiO2) layers. The dielectric layer 302B may be formed of silicon carbonitride (SiCN) and has a thickness between about 100 Å and about 10000 Å, for example, about 1000 Å.

[0033] The substrate can be any of a semiconductor substrate, a silicon wafer, a glass substrate, or the like. The substrate can be made of materials such as crystalline silicon (e.g., Si). <100> or Si <111> Materials formed from silicon oxide, strained silicon, silicon-germanium, germanium, doped or undoped polycrystalline silicon, doped or undoped silicon wafers and patterned or unpatterned wafers, silicon-on-insulator (SOI), carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, or sapphire. The substrate can have various sizes, such as 200 mm, 300 mm, 450 mm, or other diameters, and can be rectangular or square panels.

[0034] The semiconductor structure 300 also includes a boron-containing hard mask 304 formed on the film stack 302 and an oxide hard mask 306 formed on the boron-containing hard mask 304.

[0035] The concentration of boron (B) in the boron-containing hard mask 304 can be between about 20% and about 100% boron (B). The boron-containing hard mask 304 may also include one or more of silicon (Si), germanium (Ge), carbon (C), arsenic (As), antimony (Sb), oxygen (O), nitrogen (N), phosphorus (P), and hydrogen (H). The increased boron (B) content can increase the etch selectivity (i.e., the ratio of etch rate) of the boron-containing hard mask 304 relative to the underlying film stack 302.

[0036] A boron-containing hard mask 304 with a high boron (B) concentration (e.g., 90% or higher) may have high etch selectivity (e.g., 3 to 1 or greater) relative to the film stack 302 (e.g., SiO2), but low etch selectivity (e.g., 2 to 1 or lower) relative to the oxide hard mask 306. Therefore, to pattern the boron-containing hard mask 304, a thicker oxide hard mask 306 may be required, which increases the aspect ratio in the patterning and deteriorates the local CD uniformity (LCDU) in the patterned boron-containing hard mask 304. Furthermore, since it is difficult to directly oxidize boron (B) and silicon (Si) is lacking in the boron-containing hard mask 304 with a high boron (B) concentration, sidewall passivation with oxides such as silicon oxide (SiO2) within the openings of the patterned boron-containing hard mask 304 is insufficient, which also deteriorates the LCDU.

[0037] In the embodiments described herein, the boron-containing hard mask 304 may be doped with one or more metallic elements, such as tungsten (W), gold (Au), chromium (Cr), iron (Fe), gallium (Ga), hafnium (Hf), molybdenum (Mo), niobium (Nb), tin (Sn), tantalum (Ta), vanadium (V), zirconium (Zr), or any combination thereof. The concentration of the metallic element in the boron-containing hard mask 304 is between about 0.5% and about 80%. Adding a metallic dopant to the boron-containing hard mask 304 increases the etch selectivity of the oxide hard mask 306 from about 2.0 (non-metal-doped boron-containing hard mask) to, for example, greater than 8.0 (metal-doped boron-containing hard mask). Therefore, in order to pattern the boron-containing hard mask 304, a thinner oxide hard mask 306 may be required, which reduces the aspect ratio in the patterning and improves the LCDU in the patterned boron-containing hard mask 304. Furthermore, adding metal dopants to the boron-containing hard mask 304 promotes the formation of metal oxides such as tungsten oxide (W2O3), which helps to form boron oxide (B2O3) within the openings of the patterned boron-containing hard mask 304. This passivation layer formed by boron oxide (B2O3) also improves the LCDU in the patterned boron-containing hard mask 304.

[0038] The boron-containing hard mask 304 can have a thickness between about 500 Å and about 5000 Å, for example about 3000 Å.

[0039] Boron-containing hard masks 304 can be formed by any known deposition process, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), spin coating, spray coating, or other suitable deposition processes.

[0040] The oxide hard mask 306 can be formed from silicon oxide (SiO2) and deposited by a deposition process such as CVD or plasma-assisted CVD, in which tetra-ethyl-orthosilicate (TES) is used as the precursor source gas.

[0041] The oxide hard mask 306 may have a thickness between about 100 Å and about 3000 Å, for example about 1000 Å.

[0042] The semiconductor structure 300 also includes a carbon-containing hard mask 308 formed on an oxide hard mask and an anti-reflective coating (ARC) 310 formed on the carbon-containing hard mask 308. The carbon-containing hard mask 308 and the ARC layer 310 have been patterned to have openings 312 using a double-patterned lithography technique. The ARC layer 310 may include a dielectric anti-reflective coating (DAC) formed of silicon oxynitride (SiON) and a bottom anti-reflective coating (BAC) on the DARC layer to reduce surface reflection, thereby maximizing light collection efficiency in lithography.

[0043] The carbon-containing hard mask 308 can be formed from a carbon-containing material, such as boron-doped amorphous carbon. The carbon-containing hard mask 308 can be a Saphira™ Advanced Patterning Film (APF) carbon hard mask manufactured by Applied Materials, Inc., located in Santa Clara, California. The carbon-containing hard mask 308 can have a thickness between approximately 100 Å and approximately 3000 Å, for example, approximately 1000 Å.

[0044] The ARC layer 310 may have a thickness between approximately 100 Å and approximately 1000 Å, for example, approximately 350 Å.

[0045] The opening 312 in the carbon hard mask 308 and the ARC layer 310 may have a critical dimension (CD) between about 10 nm and about 100 nm and an LCDU less than about 3 nm.

[0046] Method 200 begins at frame 210, wherein an etch-back process is performed to remove the ARC layer 310 on the carbon-containing hard mask 308, as shown below. Figure 3B As shown. The etch-back process may include plasma etching using a gas mixture of O2, CF4, CHF3, and CH2F2.

[0047] In frame 220, an oxide hard mask patterning process is performed to open the oxide hard mask 306 through the opening 312 of the patterned carbon-containing hard mask 308, and stops at the boron-containing hard mask 304, as shown. Figure 3C As shown, the opening 312 of the carbon-containing hard mask 308 is transferred to the opening 314 of the patterned oxide hard mask 306. The opening 314 in the oxide hard mask 306 may have a critical dimension (CD) between about 10 nm and about 100 nm and an LCDU less than about 3 nm.

[0048] The oxide hard mask patterning process may include plasma etching using a gas mixture of C4F6, C4F8, Ar, and O2. The carbon-containing hard mask 308 is then stripped by ashing with O2.

[0049] In frame 230, a boron-containing hard mask patterning process is performed to open the boron-containing hard mask 304 through the opening 314 of the patterned oxide hard mask 306, as shown below. Figure 3D As shown, the opening 314 of the oxide hard mask 306 is transferred to the opening 316 of the patterned boron-containing hard mask 304. The opening 314 in the oxide hard mask 306 may have a critical dimension (CD) between about 10 nm and about 100 nm and an LCDU less than about 3 nm.

[0050] Boron-containing hard mask patterning processes may include processing chambers (such as...) Figure 1 The etching chamber 100 shown uses an etching gas mixture for plasma etching while maintaining the chamber temperature between -100°C and up to about 450°C.

[0051] The etching gas mixture includes etchants such as chlorine (Cl2) and hydrogen bromide (HBr), and reactant gases such as oxygen (O2). In the boron-containing hard mask 304, boron (B) reacts with the etchant to form volatile byproducts such as boron trichloride (BCl3), and metal dopants such as tungsten (W) react with Cl2 and O2 to form volatile byproducts such as tungsten chloride (WCl3). x ) and tungsten oxychloride (WO) x Cl y Therefore, adding a metal dopant to the boron-containing hard mask 304 increases the etching selectivity for the oxide hard mask 306. The reactive gas O2 promotes the formation of a passivation layer of silicon oxide (SiO2) on the sidewalls of the openings 316 of the patterned boron-containing hard mask 304. Furthermore, volatile byproducts (such as boron trichloride (BCl3)) react with metal oxides (such as tungsten oxide (W2O3)) to form boron oxide (B2O3), which can be used as a passivation layer on the sidewalls of the openings 316 of the patterned boron-containing hard mask 304. Metal chloride oxide byproducts (such as tungsten oxychloride (WO3))... x Cly The material can decompose in plasma to form a metal oxide, such as tungsten oxide (W₂O₃), which promotes the formation of boron oxide (B₂O₃), which is used as a passivation layer on the sidewalls of the openings 316 of the patterned boron-containing hard mask 304. Therefore, adding a metal dopant to the boron-containing hard mask 304 provides controllable sidewall passivation in the openings 316 of the patterned boron-containing hard mask 304, which reduces etching variability and defects (e.g., LCDU improvement) when etching the underlying film stack 302 using the patterned boron-containing hard mask 304.

[0052] In some embodiments, the etching gas mixture also includes fluorine-containing gases, such as nitrogen trifluoride (NF3) and hydrofluorocarbons (C). x H y F z Metal dopants (such as tungsten (W)) react with fluorine (F) to form non-volatile byproducts, such as tungsten fluoride (WF4), on the patterned oxide hard mask 306. This prevents clogging of the openings 312 of the oxide hard mask 306 and thus increases the etch selectivity of the oxide hard mask layer 306, and improves the LCDU in the patterned boron-containing hard mask 304. Clogging of the openings 312 prevents etchant gas from passing through the openings 312 and thus reduces etch selectivity. Furthermore, clogging of the openings may cause ion deflection in the plasma and thus cause contour bending, which degrades the LCDU.

[0053] In some embodiments, the etching gas mixture also includes a metal etchant gas, such as tungsten hexafluoride (WF6), tin chloride (SnCl4), or other gases containing gold (Au), chromium (Cr), iron (Fe), gallium (Ga), hafnium (Hf), molybdenum (Mo), niobium (Nb), tantalum (Ta), vanadium (V), zirconium (Zr), or any combination thereof, to provide a metallic element, such as tungsten (W) or tin (Sn), in the patterning process to replace or complement the metallic dopant, such as tungsten (W) or tin (Sn), in the boron-containing hard mask 304.

[0054] During etching, the chamber pressure of the etching gas mixture is also regulated. In one or more embodiments, the process pressure in the processing chamber is regulated between about 2 mTorr and about 100 mTorr, for example between about 3 mTorr and 20 mTorr, such as about 6 mTorr. An RF source or bias power can be applied to maintain the plasma formed in continuous or pulsed modes in the presence of the etching gas mixture as needed. For example, an RF power supply with a frequency of about 13.56 MHz can be applied to an inductively coupled antenna source at an energy level between about 50 watts and about 5000 watts (such as about 500 watts) to maintain the plasma in the processing chamber. Furthermore, an RF bias power with a frequency between about 2 MHz and about 13.56 MHz can be applied at an energy level between about 50 watts and about 5000 watts (such as about 4500 watts).

[0055] In one or more instances, during etching, the RF bias power and RF power supply can be pulsed into the processing chamber. The RF bias power and RF power supply can be pulsed into the processing chamber synchronously or asynchronously. In some instances, the RF bias power and RF power supply are pulsed into the processing chamber asynchronously. For example, the RF power supply pulse may be transmitted into the processing chamber before the RF bias power pulse. For example, the RF bias power may be in a pulsed mode synchronized with the RF power supply, or with a time delay relative to the RF power supply. In one or more instances, the RF power supply and RF bias power supply are pulsed between approximately 5% and approximately 75% of each duty cycle. Each duty cycle (e.g., each duty cycle between each time unit) is between approximately 0.1 milliseconds (ms) and approximately 10 ms.

[0056] In one example of an etching gas mixture, chlorine (Cl2) gas is supplied at a rate between about 50 sccm and about 1000 sccm, hydrogen bromide (HBr) gas is supplied at a rate between about 50 sccm and about 1000 sccm, and oxygen (O2) gas is supplied to the processing chamber at a rate between about 5 sccm and about 300 sccm. Fluorine-containing gases (such as nitrogen trifluoride (NF3)) are supplied at a flow rate between about 1 sccm and about 50 sccm. Metal-containing gases (such as tungsten hexafluoride (WF6)) are supplied at a flow rate between about 1 sccm and about 50 sccm.

[0057] In the embodiments described herein, a boron-containing hard mask for patterning high aspect ratio devices and a method for forming the same are provided. By introducing a metal element, whether as a metal dopant in the boron-containing hard mask or as an etchant in the patterned boron-containing hard mask, the selectivity of the boron-containing hard mask relative to the oxide hard mask for patterning is increased, and sidewall passivation by boron oxide is achieved through the formation of metal oxides within the openings of the patterned boron-containing hard mask. Therefore, the local critical size uniformity (LCDU) of the openings in the patterned boron-containing hard mask is improved, and the etch variability in patterning high aspect ratio devices is reduced.

[0058] While the foregoing relates to embodiments of this disclosure, other and further embodiments of this disclosure may be designed without departing from its basic scope, the scope of which is defined by the following claims.

Claims

1. A method for patterning a boron-containing hard mask, comprising: Patterning of oxide hard masks formed on boron-containing hard masks; and The boron-containing hard mask is patterned using the patterned oxide hard mask, wherein... The oxide hard mask comprises silicon oxide (SiO2). The boron-containing hard mask is doped with one or more metal elements, and The patterning of the boron-containing hard mask comprises: etching the boron-containing hard mask through an opening in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), and oxygen (O2).

2. The method of claim 1, wherein the concentration of boron in the boron-containing hard mask is between 20% and 100%.

3. The method of claim 1, wherein the one or more metallic elements comprise tungsten (W).

4. The method of claim 1, wherein the concentration of the one or more metal elements is between 0.5% and 80%.

5. The method of claim 4, wherein the boron-containing hard mask has an etching selectivity greater than 8 for the oxide hard mask.

6. The method of claim 1, wherein the oxide hard mask has a thickness between 100 Å and 3000 Å, and the critical size of the opening of the patterned oxide hard mask is between 10 nm and 100 nm.

7. The method of claim 1, wherein the boron-containing hard mask has a thickness between 500 Å and 5000 Å, and the opening of the patterned boron-containing hard mask is between 10 nm and 100 nm.

8. The method of claim 1, wherein the etching gas mixture further comprises a fluorine-containing gas.

9. A method for patterning a boron-containing hard mask, the method comprising: Patterning of oxide hard masks formed on boron-containing hard masks; and The boron-containing hard mask is patterned using the patterned oxide hard mask, wherein... The oxide hard mask comprises silicon oxide (SiO2), and The patterning of the boron-containing hard mask comprises: etching the boron-containing hard mask through openings in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), oxygen (O2), and a metal etchant.

10. The method of claim 9, wherein the metal-containing etchant comprises tungsten hexafluoride (WF6) or tin chloride (SnCl4).

11. The method of claim 9, wherein the concentration of boron in the boron-containing hard mask is between 20% and 100%.

12. The method of claim 9, wherein the oxide hard mask has a thickness between 100 Å and 3000 Å, and the critical size of the opening of the patterned oxide hard mask is between 10 nm and 100 nm.

13. The method of claim 9, wherein the boron-containing hard mask has a thickness between 500 Å and 5000 Å, and the openings of the patterned boron-containing hard mask are between 10 nm and 100 nm.

14. The method of claim 9, wherein the etching gas mixture further comprises a fluorine-containing gas.

15. A method for patterning a boron-containing hard mask, the method comprising: Patterning of oxide hard masks formed on boron-containing hard masks; and The boron-containing hard mask is patterned using the patterned oxide hard mask, wherein... The oxide hard mask comprises silicon oxide (SiO2). The boron-containing hard mask is doped with one or more metal elements, and The patterning of the boron-containing hard mask comprises: etching the boron-containing hard mask through openings in the patterned oxide hard mask using an etching gas mixture comprising chlorine (Cl2), hydrogen bromide (HBr), oxygen (O2), and a metal etchant.

16. The method of claim 15, wherein the concentration of boron in the boron-containing hard mask is between 20% and 10%.

17. The method of claim 15, wherein the one or more metallic elements comprise tungsten (W).

18. The method of claim 15, wherein the concentration of the one or more metal elements is between 0.5% and 80%.

19. The method of claim 15, wherein the metal-containing etchant comprises tungsten hexafluoride (WF6) or tin chloride (SnCl4).

20. The method of claim 15, wherein the etching gas mixture further comprises a fluorine-containing gas.

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