Sidewall passivation layer during high aspect ratio plasma etching and method for forming the same

Abstract

A method of forming a high aspect ratio (HAR) structure during a high aspect ratio (HAR) etching process, the method comprising sequentially or simultaneously exposing a substrate to a vapor of an etchant comprising one or more hydrofluorocarbon or fluorocarbon compounds or one or more hydrogen-containing molecules and an additive compound, the substrate having a film disposed thereon and a patterned mask layer disposed on the film; activating a plasma to generate one or more activated hydrofluorocarbon or fluorocarbon compounds or one or more activated hydrogen-containing molecules and an activated additive compound; and allowing an etching reaction to proceed between the film not covered by the patterned mask layer and the activated hydrofluorocarbon or fluorocarbon compound or the one or more activated hydrogen-containing molecules and the activated additive compound to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure.

Description

[Technical Field]

[0001] Disclosed is a method for forming a passivation layer on a sidewall using an etching gas as an additive, particularly for forming a highly conductive sidewall passivation layer, by doping with silicon, iodine, and / or carbon elements during high aspect ratio (HAR) plasma etching and / or introducing cyclic, aromatic, heterocyclic chemical structures. [Background technology]

[0002] For over 50 years, Moore's Law has driven semiconductor manufacturers to continuously reduce device feature sizes to improve transistor / chip speed and capability while maintaining a cost advantage over competitors. This presents new challenges for manufacturing processes to meet the demands of ever-smaller feature sizes and dramatically increasing aspect ratios. For example, manufacturing 3D gate-stack NAND flash memory (3D-NAND) requires the ability to etch tiny hole features into 90+ NAND layers with aspect ratios exceeding 40. Using ultra-high aspect ratio (HAR) etching, it's necessary to etch over one trillion holes onto each wafer.

[0003] The vertical isotropy of etched features is achieved by ion transport during plasma sheath formation. In principle, positive and negative particles should follow the same orbits within the holes, equalizing the charge at the bottom of the HAR holes. However, due to electron shading effects, charge can accumulate at the bottom of the HAR mask pattern, potentially leading to incomplete etching, bowing, twisting, and variations in the critical dimension (CD) between the top and bottom of the HAR stack. Therefore, many efforts have been and continue in industry to eliminate or minimize sidewall charge-up during HAR etching in order to improve etching profiles and CD control.

[0004] Plasma etching of high-aspect-ratio structures is a complex process that utilizes numerous different standard fluorocarbon etching gases to control etching rate, selectivity for the mask layer, and etching profile. Sidewall passivation layers, such as polymers, are crucial for controlling the profile and reducing bowing. Polymers deposited with fluorocarbon gases are also useful for protecting the mask layer from the impact of Ar+ ions and oxygen radicals, often with the addition of inert gases and / or oxidizers.

[0005] It is known that contact hole distortion is caused by asymmetric charging of the contact hole sidewalls, which alters the local electric field within the contact hole and changes the orientation of reactive ions within the contact hole (see Kim et al., J.Vac.Sci.Technol.A, Vol.33, 021303-5 (2015) and Negishi et al, J.Vac.Sci.Technol.B, Vol.35, 051205 (2017)). In HAR etching, ellipticity has been used to assess mask degradation. High ellipticity (close to 100%) can help avoid HAR hole twisting and reduce distortion of the etching profile.

[0006] The following are some examples of methods that have been used to adjust the properties of the passivation layer during HAR etching, but as a natural consequence, 1) the gas / chemical supply setup to the process chamber becomes complicated, 2) the uniformity of the passivation layer at the top and bottom of the HAR feature becomes insufficient, and 3) the chamber cleaning problem - some metal-containing polymer deposits on the chamber walls, which is difficult to remove completely.

[0007] Sandhu et al., in U.S. Patent Application Publication No. 20070049018, disclose a method for HAR contact etching substantially perpendicular contact holes in an oxide layer using a hard photoresist mask. The plasma etching gas is a fluorinated hydrocarbon containing one of the following: CH2F2, C4F8;C3H3F5, C4F8;CHF3;C2F6;C2HF5, CH3F, or a combination thereof. The dopant molecule contains one of the following: HI, CH3I, carbon, potassium, calcium, PF6, BF3, chloride, AsF6, or a combination thereof. The doped plasma etching gas etches substantially perpendicular contact holes through the oxide layer by doping the carbon chain polymer formed along the sidewalls of the contact holes into a conductive state during the etching process. The conductive state of the carbon chain polymer reduces charge accumulation along the sidewalls, preventing twisting of the contact holes by bleeding off the charge and ensuring proper alignment of the active area with the landing region. Etching stops at the underlying substrate.

[0008] Bera et al., U.S. Patent No. 7,846,846,B2, discloses a method for etching HAR contact openings while preventing bowing and bending of the etching profile by forming a highly conductive thin film on the sidewall of each contact opening. The conductivity of the thin film on the sidewall is enhanced by periodic ion bombardment during the etching process. The etchant is a fluorocarbon / fluorohydrocarbon gas containing at least one of C2F4, C4F6, CH2F2, or C4F8, saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons of C1-C5, such as C4H2F6, CHF3, CH2F2, or a combination thereof.

[0009] Nikhil et al.'s U.S. Patent No. 9,543,158 and U.S. Patent No. 1,017,0324 disclose various methods, apparatus, and systems for forming concave features in dielectric materials on substrates. In some cases, protective coatings are deposited using plasma-assisted atomic layer deposition (ALD), modified plasma-assisted ALD, or plasma-assisted chemical vapor deposition (CVD). Etching chemicals are combinations of fluorocarbons and oxygen, C4F6, C4F3, N2, CO, CF4, and O2. The protective layer is a ceramic material or an organic polymer. If silicon is included in the protective layer, silicon-containing reactants can be used. Silicon oxide (Si x O y ) and silicon nitride (Si x N yFor silicon-containing materials such as ), the reactant may be, for example, silane, halosilane, or aminosilane. Halosilane contains at least one halogen group, which may or may not contain a hydrogen group and / or a carbon group. Examples of halosilanes are iodosilane, bromosilane, chlorosilane, and fluorosilane. Halosilanes, and especially fluorosilanes, may form reactive halide species that can etch silicon materials, although in certain embodiments described herein, no silicon-containing reactant is present when the plasma is irradiated. In certain embodiments, the silicon-containing reactant is selected from the group consisting of SiCl4, SiH4, SiF4, SiBr4, and combinations thereof. Deposition reactions such as cyclic ALD and ALD can deposit a silicon-containing protective layer. Alternatively, non-cyclic processes such as bulk CVD deposition can deposit a silicon-containing protective layer. In certain embodiments, the silicon-containing precursor reacts with an oxidizing agent such as nitrous oxide and / or molecular oxygen to produce a protective coating which is a silicon oxide. In some other cases, silicon-containing precursors can react with relatively weak oxidizing agents. U.S. Patent No. 9,543,158 describes a method for depositing a protective sidewall coating in one example, in which the first reactant is SiCl4, which is supplied in argon as the carrier gas. The SiCl4 can be supplied at a rate of about 20 sccm, the argon at a rate of about 100 sccm, and a second reactant, such as an oxidizing agent, is supplied in a separate step, such as COS, which flows with the carrier gas at a rate of about 30 sccm. No fluorocarbon gas was supplied during the deposition process. Analysis of the film revealed a composition of about 60% oxygen, about 28% silicon, about 6% sulfur, about 5% carbon, about 0.4% fluorine, and about 0.4% chlorine. U.S. Patent No. 10170324 describes one embodiment using BCl3, N2, and H2, where BCl3 is supplied at a flow rate of approximately 50 to 1000 sccm, N2 at a flow rate of approximately 50 to 1000 sccm, and H2 at a flow rate of approximately 50 to 1000 sccm.

[0010] U.S. Patent No. 1,0361092 discloses the addition of a metal-containing component to an etching process along with a fluorocarbon etching gas, wherein the metal-containing component comprises a metal selected from at least one of tungsten (W), tin (Sn), molybdenum (Mo), ruthenium (Ru), titanium (Ti), or tantalum (Ta), and the metal source may include WF6, TiCl4, TiF4, SnH4, TaF5, RuF6, and SnCl4.

[0011] U.S. Patent No. 1,0741,407 discloses a method for adding a metal-containing gas WF6 to HAR etching to improve sidewall protection by reducing or eliminating problematic sidewall notching.

[0012] U.S. Patent Application Publication No. 20210242032 discloses a method for depositing a metal-containing protective film on the sidewall of a feature using a cyclic etching and deposition process, wherein the protective film is made of tungsten carbonitride, tungsten sulfide, tin, tin-containing compounds, molybdenum, molybdenum-containing compounds, ruthenium sulfide, aluminum sulfide, zirconium, and zirconium-containing compounds.

[0013] U.S. Patent No. 9,673,058 discloses a method for forming a tungsten- and carbon-containing sidewall passivation layer by etching features into a silicon oxide-containing film using a carbon-containing passivation gas such as hydrocarbons, fluorohydrocarbons, or fluorocarbon gases, by adding a tungsten-containing gas, such as WF6, WF5Cl, WBr6, W(CO)6, or WCl6. The addition of W is expected to improve the etching resistance of the sidewall passivation layer.

[0014] The HAR etching process has become a critical process for memory devices. Ion energy control by increasing the effective bias power of HAR features continues to advance. Significant efforts have been made to increase ion energy to overcome charge accumulation at the etching front within HAR holes. Based on bias power trends over the past few years, the required power would now exceed 20 kW. Increasing bias power presents numerous challenges. Preventing arc discharge, effective cooling, and power supply systems are all crucial for achieving high power capabilities. Furthermore, since neutral species move only by diffusion through holes, it becomes more difficult to compensate for neutral flux as the aspect ratio increases. [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] Therefore, there is a need to realize a passivation layer, particularly a highly conductive sidewall passivation layer, during HAR plasma etching. [Means for solving the problem]

[0016] A method for forming a high aspect ratio (HAR) structure in a substrate within a reaction chamber during a high aspect ratio (HAR) etching process is disclosed, and this method is: The substrate is sequentially or simultaneously exposed to the vapor of an etchant containing one or more hydrofluorocarbons or fluorocarbon compounds or one or more hydrogen-containing molecules and an additive compound, wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; Activating plasma to generate one or more activated hydrofluorocarbons or fluorocarbon compounds or one or more activated hydrogen-containing molecules and activated additive compounds; and The process involves proceeding with an etching reaction between a film not covered by a patterned mask layer and an activated hydrofluorocarbon or fluorocarbon compound, or one or more activated hydrogen-containing molecules and activated additive compounds, thereby selectively etching the film from the patterned mask layer and forming a HAR patterned structure; The disclosed methods may include one or more of the following embodiments: The process further includes the step of introducing an oxidizing agent into the reaction chamber, the oxidizing agent being selected from O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof; • The oxidizing agent is O2; • The oxidizing agent is O3; • The oxidizing agent is CO; • Before introducing it into the chamber, the etching compound, additive, and oxygen-containing gas are mixed to produce a mixture; • Introduce etching compounds and additives separately from the oxygen-containing gas; • Continuously introduce an oxygen-containing gas and an iodine-containing etching compound; • Oxygen-containing gas accounts for approximately 0.01% v / v to approximately 99.9% v / v of the total volume of etching compound, additives, and oxygen-containing gas; • Oxygen-containing gas accounts for approximately 0.01% v / v to approximately 10% v / v of the total volume of etching compound, additive, and oxygen-containing gas; The process further includes the step of introducing an inert gas into a reaction chamber, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N2; • The inert gas is Ar; • The inert gas is N2; • Before introducing it into the chamber, the etching compound, additives, and inert gas are mixed to produce a mixture; • In addition to the inert gas, etching compounds and additives are introduced; • Inert gas is continuously introduced, and etching compounds and additives are introduced in pulses; • The inert gas accounts for approximately 0.01% v / v to 99.9% v / v of the total volume of the etching compound, additives, and inert gas vapors; • The inert gas accounts for approximately 90% v / v to 99.9% v / v of the total volume of the etching compound, additives, and inert gas vapors; • The patterned structure is a 3D NAND aperture; • The patterned structure is the contact hole; The HAR patterned structure is a 3D NAND contact hole, DRAM contact, channel hole, 3D NAND channel hole, or 3D NAND slit contact; Plasma-activated hydrofluorocarbons or fluorocarbon compounds and activated additive compounds react with the film to form volatile byproducts; • Volatile by-products are removed from the reaction chamber; • A sidewall passivation layer is formed on the sidewall of the HAR patterned structure; • The sidewall passivation layer is a polymer passivation layer; • The sidewall passivation layer is a highly conductive passivation layer; • The sidewall passivation layer is a fluorocarbon passivation layer; • A highly conductive sidewall passivation layer is formed on the sidewall of the HAR patterned structure; The conductivity of a highly conductive sidewall passivation layer formed using one or more activated hydrofluorocarbons or fluorocarbon compounds or one or more activated hydrogen-containing molecules and an activated additive compound is at least approximately 10% higher than the conductivity of a highly conductive sidewall passivation layer formed using activated hydrofluorocarbons or fluorocarbon compounds or one or more activated hydrogen-containing molecules without the addition of the activated additive compound; The conductive state of the polymer passivation layer reduces charge accumulation along the sidewalls, preventing twisting of HAR structures such as holes by bleeding off the charge, and ensuring proper control of CD fluctuations when the bias power is low or absent. The hydrogen-containing etching gas is a halogen-containing acidic gas containing H2, methane, or HCl, HBr, HI, or a combination thereof; • The etching gas containing hydrogen is H2; • The hydrogen-containing etching gas is methane; • The hydrogen-containing etching gas is a halogen-containing acidic gas containing HCl, HBr, HI, or a combination thereof; • Halogen-containing acidic gases include HCl, HBr, HI, or combinations thereof; The hydrofluorocarbon or fluorocarbon compound is a fluorocarbon and hydrofluorocarbon compound containing nitrogen, oxygen, iodine, or sulfur, including CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, C4H2F6, CHF3, CH2F2, or saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons of C1-C5, or combinations thereof, and one or more hydrogen-containing molecules are H2 or halogen-containing acidic gases containing HCl, HBr, HI, or combinations thereof; • Hydrofluorocarbons or fluorocarbon compounds include CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons of C1-C5, such as C4H2F6, CHF3, CH2F2, or combinations thereof; • The hydrofluorocarbon or fluorocarbon compound is C4H2F6; • The hydrogen-containing molecule is H2; • The hydrogen-containing molecules are halogen-containing acidic gases containing HCl, HBr, HI, or combinations thereof; • The halogen-containing acidic gas includes HCl, HBr, HI, or a combination thereof; · The additive compound has the following formula and contains silicon, iodine, and / or carbon elements: C n R 1 R 2 R 3 I, SiR 1 R 2 R 3 I, SiR 1 R 2 I x F (2-x) , SiRI y F (3-y) , SiI z F (4-z) or C n F (2n+1) I (where n = 1 - 10; x = 1 - 2; y = 1 - 3; z = 1 - 3; R, R 1 , R 2 , and R 3 are each independently selected from H, a linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group of C1 - C 10 ; R 1 and R 2 , R 2 and R 3 , or R 1 and R 3 may be linked to form a cyclic group); · The additive compound is selected from the following

Chemical formula

Chemical formula

[0017] Furthermore, a method for forming HAR patterned structures is also disclosed, and this method is: A step of sequentially or simultaneously exposing a substrate to one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and SiH2I2 vapor, wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; A step of activating plasma to generate one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and activated SiH2I2; and The method includes the step of carrying out an etching reaction between a film not covered by a patterned mask layer and one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more activated hydrogen-containing molecules and activated SiH2I2 to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure; the disclosed method may include one or more of the following embodiments: The process further includes the step of introducing an oxidizing agent into the reaction chamber, the oxidizing agent being selected from O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof; The process further includes the step of introducing an inert gas into a reaction chamber, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N2; • A highly conductive sidewall passivation layer is formed on the sidewall of the HAR patterned structure; The conductivity of a highly conductive sidewall passivation layer formed using one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more activated hydrogen-containing molecules and activated SiH2I2 is at least approximately 10% higher than the conductivity of a highly conductive sidewall passivation layer formed using one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more activated hydrogen-containing molecules without the addition of activated SiH2I2; • The HAR patterned structure formed on the film has an aspect ratio of approximately 1:1 to approximately 200:1; • Further includes introducing additional etching gases into the reaction chamber, where the additional etching gases include cC4F8, C4F8, cC5F8, C5F8, C4F6, CF4, CH3F, CF3H, CH2F2, C3HF7, C3F6, C3H2F6, C3H2F4, C3H3F5, C4HF7, C5HF9, C3F6, C3F8, CF3I, C2F3I, C2F5I, C3F7I, 1-iodoheptafluoropropane (1-C3F7I), 2-iodoheptafluoropropane (2-C3F7I), C3HF7, COS, FNO, FC≡N, CS2, SO2, SF6, trans-1,1,1,4, Selected from the group consisting of 4,4-hexafluoro-2-butene (trans-C4H2F6), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C4H2F6), hexafluoroisobutene (C4H2F6), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C4H2F6), 1,1,2,2,3-pentafluorocyclobutane (C4H3F5), 1,1,2,2-tetrafluorocyclobutane (C4H4F4), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6), and combinations thereof; The film is a silicon-containing film that contains O and / or N, and optionally contains dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof; The substrate is simultaneously exposed to a) vapor of one or more fluorocarbons or hydrofluorocarbon compounds or one or more hydrogen-containing molecules, and b) SiH2I2; The method does not involve exposing a substrate having a highly conductive sidewall passivation layer to a non-etched sidewall passivation layer deposition step after or between etching steps; The method includes, after or between etching steps, exposing a substrate having a highly conductive sidewall passivation layer to a non-etched sidewall passivation layer deposition step; The non-etching sidewall passivation layer deposition step does not involve the use of vapors of one or more fluorocarbons or hydrofluorocarbon compounds or one or more hydrogen-containing molecules, and does not involve the use of SiH2I2; • The non-etching sidewall passivation layer deposition step does not involve the use of SiH2I2.

[0018] Representation and Nomenclature The following detailed description and claims utilize a number of abbreviations, symbols, and terms that are generally well known in the art, including:

[0019] As used herein, the indefinite articles "a" or "an" refer to one or more.

[0020] As used herein, the terms “about,” “approximately,” or “about” in the text or claims mean ±10% of the stated value.

[0021] As used herein, "room temperature" in the text or claims means approximately 20°C to approximately 25°C.

[0022] The terms “wafer” or “patterned wafer” refer to a wafer having a stack of any existing films, including silicon-containing films, on a substrate, and a patterned hard mask layer on the stack of any existing films, including silicon-containing films, formed for pattern etching.

[0023] The term "substrate" refers to one or more materials on which a process is performed. A substrate may refer to a wafer or patterned wafer having one or more materials on which an etching process is performed. A substrate may be any suitable wafer used in the manufacture of semiconductors, photovoltaics, flat panels, or LCD-TFT devices. A substrate may also have one or more layers of different materials already deposited on it from a previous manufacturing step. For example, a wafer may include silicon layers (e.g., crystalline, amorphous, porous, etc.), silicon-containing layers (e.g., SiO2, SiN, SiON, SiCOH, etc.), metal-containing layers (e.g., copper, cobalt, ruthenium, tungsten, indium, platinum, palladium, nickel, ruthenium, gold, etc.), or combinations thereof. Furthermore, a substrate may be planar or patterned. A substrate may be a photoresist film patterned with an organic material. The substrate may be an oxide layer used as a dielectric material in MEMS, 3D NAND, MIM, DRAM, or FeRam device applications (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.), a nitride-based film used as an electrode (e.g., TaN, TiN, NbN), or a metal-containing or metal alloy-based film (e.g., InGaAs, In) which is a promising candidate to replace silicon in future CMOS systems. x O y This may include (x=0.5~1.5, y=0.5~1.5), InSnO(ITO), InGaZnO(IGZO), InN, InP, InAs, InSb, In2S3, or In(OH)3, etc. Those skilled in the art will recognize that the terms “film” or “layer” as used herein refer to the thickness of any material that is placed on or spread over a surface, and that surface may be a trench or a line. Throughout this specification and the claims, a wafer and any associated layer thereon are referred to as a substrate.

[0024] The term "pattern etching" or "patterned etching" refers to etching non-planar structures, such as stacks of silicon-containing films, beneath a patterned hard mask layer.

[0025] As used herein, the terms “etch” or “etch” mean the removal of material by ion bombardment, remote plasma, or chemical vapor phase reaction between an etching compound and / or plasma and an etching gas and a substrate, and refer to isotropic etching processes and / or anisotropic etching processes. Isotropic etching processes involve a chemical reaction between an etching compound and a substrate, removing a portion of the material on the substrate. This type of etching process includes chemical dry etching, vapor phase chemical etching, and thermal dry etching. Isotropic etching processes create lateral or horizontal etching profiles on the substrate. Isotropic etching processes create recesses or horizontal recesses in the sidewalls of pre-formed apertures on the substrate. Anisotropic etching processes include plasma etching processes (i.e., dry etching processes) in which the chemical reaction is accelerated vertically by ion bombardment, resulting in the formation of sidewalls perpendicular to the substrate along the edges of masked features (Manos and Flamm, Thermal etching an Introduction, Academic Press, Inc. 1989 pp.12-13). Plasma etching processes create vertical etching profiles on a substrate. Plasma etching processes create vertical vias, apertures, trenches, channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, slit etchings, self-aligned contacts, self-aligned vias, supervias, and more on the substrate.

[0026] The term "mask" refers to a layer that resists etching. A mask layer can be placed on top of the layer to be etched. The term "mask layer" also refers to a hard mask layer. A mask layer may be an amorphous carbon (aC) layer, a doped aC layer, a photoresist layer, an anti-reflective layer, an organic planarization layer, or a combination thereof. A mask layer may also be a silicon layer such as polySi, a metal oxide such as Ti, Al, Zr, or Hf, or an oxide, or a combination thereof.

[0027] The term "aspect ratio" refers to the ratio of the height of a trench (or aperture) to its width (or aperture diameter).

[0028] The term "etching stop" refers to the layer beneath the layer being etched, which protects the layer below it.

[0029] The term "device channel" refers to a layer that is part of the actual device, and any damage to it will affect device performance.

[0030] The term "selectivity" refers to the ratio of the etching rate of one material to the etching rate of another material. The term "selective etching" means that one material is etched more than the other, or in other words, that the etching selectivity between the two materials is greater than or less than 1:1.

[0031] The terms "via," "aperture," "trench," and "hole" may be used interchangeably and generally refer to openings in interlayer insulation.

[0032] The terms "low bias power" or "reduced bias power" refer to bias power lower than that of the baseline process.

[0033] As used herein, the term “additive” refers to a compound or gas that is added to other etching compounds during the etching process to improve the etching properties to some extent, such as improving profile characteristics such as bowing, CD, and ellipticity.

[0034] As used herein, the term "ellipticity" refers to a method for measuring the degradation of a mask, and in etching applications, the ellipticity of an etched hole is estimated for simplification by (width of short hole / width of long hole) * 100%; therefore, the ellipticity of a perfectly circular hole is defined as 100%.

[0035] As used herein, the abbreviation "NAND" refers to a "Negated AND" or "Not AND" gate, the abbreviation "2D" refers to a two-dimensional gate structure on a flat substrate, and the abbreviation "3D" refers to a three-dimensional or vertical gate structure in which gate structures are stacked vertically.

[0036] As used herein, the term “mercury probe” refers to an electrical probe device for rapid and non-destructive contact with a sample for electrical characterization. When the contact between mercury and the sample is ohmic (non-rectifier), a current-voltage measuring instrument can be used to measure resistance, leakage current, or current-voltage characteristics. Resistance can be measured with a bulk sample or a thin film. The thin film can be made of any material that does not react with mercury. The diameter of the mercury contact of the mercury probe used herein is 760 μm.

[0037] As used herein, the term "conductivity" is the reciprocal of electrical resistivity and represents the ability of a material to conduct electric current. As used herein, the unit of electrical conductivity is Siemens per centimeter (S / cm). This is measured using a mercury probe.

number

[0038] As used herein, the term “highly conductive sidewall passivation layer” refers to the electrical conductivity of a sidewall passivation layer that exceeds the conductivity of the C4F8 polymer, specifically 2.14 × 10⁻⁶. -9 It is calculated as S / cm.

[0039] It should be noted that the terms “film” and “layer” may be used interchangeably in this specification. It will be understood that a film may correspond to or be related to a layer, and that a layer may be called a film. Furthermore, those skilled in the art will recognize that, as used herein, the terms “film” or “layer” refer to the thickness of several materials applied or extended on a surface, and that the surface may range from as large as an entire wafer to as small as a trench or line.

[0040] In this specification, the terms “etching compound,” “etchant,” “etching gas,” “etch gas,” and “process gas” may be used interchangeably when the etching compound is in a gaseous state at room temperature and ambient pressure. It is understood that the etching compound may correspond to or be related to an etching gas, etchant, or process gas, and that an etching gas, etchant, or process gas may refer to an etching compound.

[0041] As used herein, the term "frequency (Fr)" refers to the frequency at which the plasma signal switches between low and high power. Frequency is expressed as cycles per second, or Hz.

[0042] As used herein, the term “duty cycle (DC)” refers to the percentage of time that a plasma signal is maintained at high power. This is typically expressed as a percentage of time. For example, with DC: 70%, radio frequency (RF) power at 2M: 7000W and 200W respectively, and Fr: 500Hz, this means that the plasma signal is at 7000W (i.e. high power) for 70% of a cycle and at 200W (i.e. low power) for 30% of the cycle, meaning the plasma signal switches between 7000W and 200W at a cycle rate of 500Hz (500 cycles per second).

[0043] In this specification, standard abbreviations for elements from the periodic table are used. It should be understood that elements may be represented by these abbreviations (for example, Si means silicon, N means nitrogen, O means oxygen, C means carbon, H means hydrogen, F means fluorine, etc.).

[0044] A unique CAS registry number (i.e., "CAS") assigned by the Chemical Abstract Service is provided to identify the specific molecule being disclosed.

[0045] Note that silicon-containing films such as SiN and SiO are enumerated throughout the specification and claims without providing their appropriate stoichiometry. Silicon-containing films include pure silicon (Si) layers such as crystalline Si, polysilicon (p-Si or polycrystalline Si), or amorphous silicon; silicon nitride (Si k N l ) layer; silicon dioxide (Si n O m A silicon nitride layer; or a mixture thereof may be included, where k, l, m, and n are all in the range of 0.1 to 6. Preferably, the silicon nitride is Si, where k and I are each in the range of 0.5 to 1.5. k N l More preferably, silicon nitride is Si3N4. In this specification, SiN in the following description means Si k N lIt may be used to represent a silicon-containing layer. Preferably, silicon oxide has Si where n ranges from 0.5 to 1.5 and m ranges from 1.5 to 3.5. n O m That is. More preferably, silicon oxide is SiO2. In this specification, SiO in the following specification may be used to represent a Si n O m -containing layer. The silicon-containing film may be a silicon-based dielectric material such as an organic-based or silicon oxide-based low dielectric constant dielectric material such as Black Diamond II or III material by Applied Materials, Inc. having SiOCH. The silicon-containing film may contain Si where a, b, c range from 0.1 to 6. a O b N c . The silicon-containing film may also contain dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi and / or Ge, and combinations thereof.

[0046] The term "independently" when used in the context of describing R groups should be understood to mean that the R groups of interest are selected independently not only with respect to other R groups having the same or different subscripts or superscripts, but also with respect to any additional species of the same R group. For example, in the formula MR 1 x (NR 2 R 3 ) (4-x) (where M is an atom and x is 2 or 3), the two or three R 1 groups may be the same as each other, or the same as R 2 or R 3 , but are not necessarily identical. Further, unless otherwise specified, the values of the R groups should be understood to be independent of each other when used in different formulas.

[0047] In this specification, a range may be expressed as approximately from one specific value and / or approximately from another specific value. Where such a range is expressed, it should be understood that other embodiments, along with all combinations within the range, are from one specific value and / or from another specific value.

[0048] Any reference in this specification to “one embodiment” or “a particular embodiment” means that certain features, structures, or characteristics described in relation to an embodiment may be included in at least one embodiment of the present invention. The phrase “in one embodiment” appearing in various places in this specification does not necessarily refer to the same embodiment, and another or alternative embodiment is not necessarily mutually exclusive with other embodiments. The same applies to the term “implementation.”

[0049] For a further understanding of the nature and purpose of the present invention, the following detailed description should be referenced in conjunction with the accompanying drawings. In the drawings, similar elements are given the same or similar reference numerals. [Brief explanation of the drawing]

[0050] [Figure 1] This is the conductivity of C4H2F6 measured on a flat wafer, with and without the additive CH3I. [Figure 2] This is the conductivity of C4H2F6 measured on a flat wafer, with and without the additive C4F9I. [Figure 3] This is the conductivity of C4H2F6 measured on a flat wafer, with and without the additive SiH2I2. [Figure 4] This compares the ER and selectivity of C4H2F6 with and without the additive CH3I. [Figure 5] This is a comparison of the sidewalls of C4H2F6 Boeing with and without the additive CH3I. [Figure 6] This is a comparison of ellipticity with and without the additive CH3I. [Figure 7]This is a comparison of the critical dimension (CD) of C4H2F6 with and without CH3I additive at a bias power of 7000W. [Figure 8] This is a comparison of CDs for C4H2F6 with and without CH3I additive at a bias power of 5600W. [Figure 9] This is a comparison of CD values ​​for C4H2F6 with and without CH3I additive at a bias power of 4200W. [Figure 10] This refers to the chemical composition of various polymers and their electrical conductivity. [Modes for carrying out the invention]

[0051] A method is disclosed for forming a sidewall passivation layer on a sidewall using an etching gas as an additive by doping with Si, I, and / or C elements in a high aspect ratio (HAR) plasma etching process. The disclosed method uses an etching compound or etchant containing a hydrofluorocarbon / fluorocarbon etching gas or hydrogen-containing molecule and an additive or additive chemical in a HAR plasma etching process to form a sidewall passivation layer by doping with Si, I, and / or C elements. The sidewall passivation layer may be a polymer passivation layer, a highly conductive passivation layer, and / or a fluorocarbon passivation layer. By applying the additive, HAR plasma etching profile characteristics, such as bowing, CD, and ellipticity, are improved. The sidewall passivation layer is useful for reducing sidewall etching and reducing the formation of bowing and scalloping. More specifically, by applying an additive in a smaller amount compared to the amount of hydrofluorocarbon / fluorocarbon etching gas or hydrogen-containing molecules added, HAR plasma etching profile characteristics such as bowing, CD, and ellipticity were improved. In some embodiments, the ratio of the additive compound to the flow rate (sccm and / or moles / second) of the hydrofluorocarbon / fluorocarbon etching gas or hydrogen-containing molecules may be in the range of 1:200 to 1:10 under the same conditions.

[0052] The disclosed sidewall passivation layer may be a highly conductive sidewall passivation layer. Therefore, the disclosed method for forming a sidewall passivation layer on a sidewall includes a method for forming a highly conductive sidewall passivation layer on a sidewall. The disclosed method is a method for forming a highly conductive sidewall passivation layer on a sidewall using an etching gas as an additive by doping with Si, I, and / or C elements in a HAR plasma etching process. The disclosed method uses an additive or additive chemical in a HAR plasma etching process to form a highly conductive sidewall passivation layer by doping with Si, I, and / or C elements. The highly conductive sidewall passivation layer may be a polymer passivation layer or a fluorocarbon layer. The conductive state of the polymer passivation layer reduces charge accumulation along the sidewall, prevents twisting of HAR structures such as holes by bleeding off the charge, and ensures proper control of CD fluctuations when the bias power is at low to no levels. The application of additives improved HAR plasma etching profile characteristics, such as bowing, CD, and ellipticity. Highly conductive sidewall passivation layers are useful for reducing sidewall etching and minimizing bowing and scallop formation. By applying additives, in some embodiments, the bias power can be reduced by at least about 10% compared to when no additives are used. In some embodiments, the application of additives may eliminate the need for bias power altogether. Disclosed etching compounds that use etching gases as additives by doping with Si, I, and / or C elements may have less or no dependence on bias power compared to etching compounds without additives.

[0053] The disclosed method can also be considered low-bias-energy plasma etching because it has minimal sidewall charge and allows for a reduced plasma bias power, which is thought to be necessary for reactive ions to reach the bottom of the HAR trench. In addition, the disclosed etching gas or processing gas or etchant, including additives, does not contain elements that are difficult to clean, thereby minimizing contamination of the reaction chamber and reducing tool maintenance / downtime.

[0054] The disclosed method relates to plasma etching a patterned wafer or substrate using a hydrofluorocarbon / fluorocarbon etching gas or a hydrogen-containing etching gas and an additive gas. The disclosed method relates to plasma etching a patterned wafer or substrate for a predetermined time, with or without bias power, using a hydrofluorocarbon / fluorocarbon etching gas or a hydrogen-containing etching gas, such as a halogen-containing acidic gas including H2, methane, or HCl, HBr, HI or a combination thereof, and an additive gas. The predetermined time can range from 0 to 1000 seconds to stabilize the pressure and gas flow in the chamber before activating the plasma.

[0055] The disclosed additive or additive chemical contains elements of Si, I, and / or C having the following formula: CR 1 R 2 R 3 I, SiR 1 R 2 R 3 I, SiR 1 R 2 I x F (2-x) , SiRI y F (3-y) , SiI z F (4-z) , or C n F (2n+1) I (In the equation, n = 1 to 10; x = 1 to 2; y = 1 to 3; z = 1 to 4; R, R) 1 , R 2 , and R 3 These are H, D (deuterium), and C1-C, respectively, independently. 10 (Selected from linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl groups). 1 and R 2 , R 2 and R 3 , or R 1 and R 3 They may be linked together to form a cyclic group.

[0056] The above formula CR 1 R 2 R 3 Exemplary additives I may include the following: [ka]

[0057] The above formula SiR 1 R 2 R 3 Exemplary additives I may include the following: [ka]

[0058] The above formula SiR 1 R 2 I x F (2-x) Exemplary additives may include the following: [ka]

[0059] The above formula SiRI y F (3-y) Exemplary additives may include the following: [ka]

[0060] The above equation SiI z F (4-z) Exemplary additives may include the following: [ka]

[0061] formula C n F (2n+1) Exemplary additives I may include the following: [ka]

[0062] The disclosed additives may be silicon-containing compounds such as the following: [ka]

[0063] Table 1 lists some exemplary disclosed additives containing Si, iodine, and / or C. These molecules are commercially available or can be synthesized by methods known in the art. Their structural formulas, CAS numbers, and boiling points are shown in the table. Disclosed additives containing Si, iodine, and / or C may also include their isomers.

[0064] [Table 1]

[0065] [Table 2]

[0066] More specifically, the disclosed additive is formula SiR 1 R 2 I x F (2-x) The equation has such that x = 1 to 2; R, R 1and R 2 These are H, D (deuterium), and C1-C, respectively, independently. 10 Selected from linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl groups. 1 and R 2 They may be linked together to form a cyclic group.

[0067] Formula SiR 1 R 2 I x F (2-x) Examples of additives having the following characteristics include: [ka]

[0068] Formula SiR 1 R 2 I x F (2-x) Exemplary disclosed additives include SiH2I2, which is listed in Table 1. The CAS number for SiH2I2 is 13760-02-6. The boiling point of SiH2I2 is 153°C at a pressure of 760 Torr, and therefore SiH2I2 is suitable for use as an etching gas, as shown in the following examples.

[0069] Since high volatility is desirable for etching compounds, high volatility is also required for additive chemicals. As mentioned above, small alkyl groups are used as substituents on the silicon in the additive, and the additives disclosed thereby have high volatility. Another advantage of using alkyl substituents is that the formation of insufficient carbon leaving groups increases the likelihood of carbon being incorporated into the sidewall passivation. The use of aromatic substituents on silicon has also been proposed in new molecules, as the conductivity can be improved by including aromatic groups in the sidewall passivation. Substitution on aromatic groups is also interesting, as the conductivity can be altered in the electronics of the aromatic ring. However, those skilled in the art will understand that low-volatility etching materials can also be used. Low-volatility etching materials can be used in various ways, such as increasing the volatility by heating the source of the low-volatility etching material, including heating a container or cylinder containing the low-volatility etching material and a gas line connected to the etching tool, or using a bubbler method in which an inert gas is blown through the liquid low-volatility etching material.

[0070] The disclosed additives are suitable for tuning the properties of passivation layers formed on the sidewalls of high-aspect-ratio holes / trenches. Sidewall passivation and downward etching occur simultaneously. The passivation layer may originate from a carbon source in the plasma etching gas, a reaction between the etching gas and the exposed material, or redeposition of by-products from the etching process. The passivation layer is a protective layer. The passivation layer may be a polymer layer, a highly conductive passivation layer, and / or a fluorocarbon passivation layer. The passivation layer is useful for reducing sidewall etching and reducing the formation of bowing and scalloping. The passivation layer assists in complete etching. The disclosed additives are suitable for tuning the properties of highly conductive passivation layers formed on the sidewalls of high-aspect-ratio holes / trenches. The conductivity of the highly conductive sidewall passivation layer formed using the disclosed etching gas and activating additive compound is at least about 10% higher than the conductivity of the highly conductive sidewall passivation layer formed using the disclosed etching gas without the addition of the activating additive compound. Additives to the etchant significantly affect the chemical composition of the sidewall passivation by introducing conductive elements and / or chemical bonds, thereby positively affecting the conductivity of the sidewall passivation. During the plasma etching process, the potential at the bottom of the structure becomes positively charged while the sidewalls become negatively charged, creating an undesirable local electric field within the structure. Only high-energy ions with energy greater than the potential difference along the local electric field can reach the bottom. As the conductivity of the sidewall passivation increases, the sidewall charge dissipates rapidly. The required bias power is lower than that of the baseline process.

[0071] The disclosed etching gas or etchant or etching compound may be a fluorocarbon or hydrofluorocarbon compound containing nitrogen, oxygen, iodine, or sulfur. Examples of disclosed fluorocarbon / hydrofluorocarbon compounds include CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons of C1-C5, such as C4H2F6, CHF3, CH2F2, or combinations thereof.

[0072] The disclosed etching gas or etching compound may be a hydrogen-containing gas. Examples of disclosed hydrogen-containing gases include H2, or halogen-containing acidic gases such as HCl, HBr, HI, or combinations thereof.

[0073] The disclosed etching compounds include silicon oxide (SiO), silicon nitride (SiN), pure silicon (Si) (such as crystalline Si), polysilicon (p-Si or polycrystalline Si); amorphous silicon, low dielectric constant SiCOH, SiOCN, SiC, SiON, and Si a O b H c C d N e (a>0; b, c, d, e≧0); Suitable for etching silicon-containing films containing layers of metal-containing films (e.g., copper, cobalt, ruthenium, tungsten, indium, platinum, palladium, nickel, ruthenium, gold, etc.). The silicon-containing film may contain alternating layers of SiO and SiN (ONON) or alternating layers of SiO and p-Si (OPOP). The silicon-containing film contains O and / or N. The silicon-containing film may also contain dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

[0074] The disclosed etching compounds and additives are provided with a purity higher than 95% v / v, preferably higher than 99.99% v / v, and more preferably higher than 99.999% v / v. The disclosed fluorocarbons / hydrofluorocarbons and additives contain less than 5% by volume of trace gaseous impurities, including impurity gases such as N2 and / or H2O and / or CO2 in amounts of less than 150 ppm by volume. Preferably, the water content in the plasma etching gas is less than 20 ppm by weight. The purified product can be produced by distillation and / or by passing the gas or liquid through a suitable adsorbent such as a 4 Å molecular sieve.

[0075] The disclosed etching compounds and additives contain any of their isomers in less than 10% v / v, preferably less than 1% v / v, more preferably less than 0.1% v / v, and even more preferably less than 0.01% v / v, which can be purified by gaseous or liquid distillation to remove the isomers and may provide better process repeatability.

[0076] The disclosed etching compound selectively etches a silicon-containing layer from an embedded landing layer or material, which is a metal layer located at the bottom of the structure to be etched in most applications. The disclosed etching compound does not etch the metal landing layer. The embedded landing layer may be an etching stop layer or a diffusion barrier layer. The material for the metal landing layer may be a tungsten metal worldline with a 3D NAND structure, and / or another metal such as W, Cu, Al, Ru, Pt, Ti, Ta, Ni, Co, Mo, Mn, Pd, Ir, Nb, Cr, Rh, V, Au, Ag, or a combination thereof, and / or an etching stop layer such as a metal, metal oxide, or nitride layer (e.g., AlO, WO, HfO, TiO, TaO, InO, CrO, RuO, CoO, MoO, ZrO, SnO, TiN, TaN, HfN, AlN, WN, MoN, NiN, NbN, CrN, RuN, CoN, ZrN, SnN, or a combination thereof).

[0077] The disclosed etching compounds can be used to plasma etch silicon-containing films on a substrate. The disclosed plasma etching method may be useful in the manufacture of semiconductor devices such as NAND or 3D NAND gates, or flash or DRAM memory or transistors such as fin-shaped field-effect transistors (FinFETs), gate-all-around (GAA) FETs, nanowire FETs, nanosheet FETs, forksheet FETs, complementary FETs (CFETs), bulk complementary metal oxide semiconductors (bulk CMOS), MOSFETs, and fully depleted silicon-on-insulator (FD-SOI) structures. The disclosed etching compounds may be useful in other areas of application, such as different front-end of the line (FEOL) and back-end of the line (BEOL) etching applications. Furthermore, the disclosed etching compounds can be used to interconnect memory to logic on a substrate, to etch Si in 3D through-silicon via (TSV) etching applications, and in MEMS applications.

[0078] The disclosed etching method includes providing a reaction chamber having a substrate disposed therein. The reaction chamber may be an enclosure or chamber in any device in which the etching method is performed, such as a reactive ion etching (RIE), CCP with a single or multiple frequency RF source, inductively coupled plasma (ICP), or microwave plasma reactor, or other types of etching systems capable of selectively removing a portion of a silicon-containing film or generating active species. Those skilled in the art will recognize that different plasma reaction chamber designs provide different electronic temperature control. Suitable commercially available plasma reaction chambers include, but are not limited to, the Applied Materials magnetically enhanced reactive ion etcher sold under the trademark eMAX®, or the Lam Research Dual CCP reactive ion etcher dielectric etching product line sold under the trademark 2300® Flex®, or the Advanced Micro-Fabrication Equipment Inc. China (AMEC) Primo SSC HD-RIE etcher. The RF power in them may be pulsed to control the plasma characteristics and thereby further improve the etching performance (selectivity and damage).

[0079] The reaction chamber may contain one or more substrates. For example, the reaction chamber may contain 1 to 200 silicon wafers having a diameter of 25.4 mm to 450 mm. The substrate may be any suitable substrate used in semiconductor, photovoltaic, flat panel, or LCD-TFT device manufacturing. Examples of suitable substrates include wafers such as silicon, silica, glass, Ge, SiGe, GeSn, InGaAs, GaSb, INP, or GaAs wafers. The wafer will have multiple films or layers on it from a previous manufacturing step, including silicon-containing films or layers. The layers may or may not be patterned. Examples of suitable layers, but not limited to, silicon (amorphous silicon, p-Si, crystalline silicon, any of which may be further p-doped or n-doped with B, C, P, As, Ga, In, Sn, Sb, Bi and / or Ge), silica, silicon nitride, silicon oxide, silicon oxynitride, Si a O b H c C d N e (wherein a > 0 and b, c, d, e ≥ 0), Ge, SiGe, GeSn, InGaAs, GaSb, InP; amorphous carbon with or without dopants, anti-reflective coatings, photoresist materials, metal oxides such as AlO, TiO, HfO, ZrO, SnO, TaO, or metal nitride layers such as AlN, ZrN, SnN, HfN, titanium nitride, tantalum nitride, etc., or combinations thereof, mask layer materials; silicon nitride, polysilicon, crystalline silicon, silicon carbide, SiON, SiCN, or combinations thereof, device channel materials such as crystalline silicon, epitaxial silicon, doped silicon, Si a O b H c C d N eEtching stop layer materials include those such as (wherein a>0 and b, c, d, e≧0) or combinations thereof. Amorphous carbon (aC) is a carbon film deposited using the PE-CVD process. Its composition is mainly carbon, with some hydrogen components. Doped aC is an amorphous carbon film in which dopants are additionally deposited during the deposition process. Dopants may include boron, zirconium, aluminum, titanium, and tungsten. Carbon films can also be deposited using a spin-on process, as opposed to the PE-CVD process. Silicon oxide layers can form dielectric materials such as organic-based or silicon oxide-based low dielectric materials (e.g., porous SiCOH films). Exemplary low dielectric materials are sold by Applied Materials under the trademark names Black Diamond II or III. Furthermore, layers containing tungsten or precious metals (e.g., platinum, palladium, rhodium, or gold) may be used. Furthermore, an example of a silicon-containing film is Si a O b H c C d N e (wherein a > 0; b, c, d, e ≥ 0) is possible. Throughout the specification and claims, wafers and any associated layers thereof are described as substrates.

[0080] The disclosed etching method includes pumping the reaction chamber to a high vacuum after placing the substrate in the chamber and before introducing the disclosed fluorocarbon / hydrofluorocarbon into the chamber. The high vacuum can be in the range of 0.01 mTorr to 10 mTorr.

[0081] An inert gas is also introduced into the reaction chamber to receive the plasma. The inert gases include He, Ar, Xe, Kr, Ne, and N. 2、This may be he or a combination thereof. The etching gas and inert gas may be mixed before introduction into the chamber so that the inert gas constitutes about 0.01% v / v to about 99.9% v / v of the resulting mixture. Alternatively, the inert gas may be introduced into the chamber continuously, while the etching gas is introduced intermittently.

[0082] The activated etching gas from the chamber exhaust may be measured using a quadrupole mass spectrometer (QMS), optical emission spectrometer, FTIR, or other radical / ion measurement tool to determine the type and number of species generated. If necessary, the flow rates of the etching gas and / or inert gas may be adjusted to increase or decrease the number of radical species generated.

[0083] The disclosed etching compounds and additives may be mixed with other gases or co-reactants either before or during their introduction into the reaction chamber. Preferably, the gases may be mixed before introduction into the chamber to provide a uniform concentration of the mixed gases.

[0084] In another option, the vapors of the disclosed etching compounds and additives may be introduced into the chamber independently of other gases, for example, when it is easier to deliver two or more gases independently or in a reaction with them.

[0085] In another option, the disclosed etching compound and additive gases are only two gases used during the etching process.

[0086] In another alternative configuration, the disclosed etching compound, additive gas, and inert gas are only three gases used during the etching process.

[0087] Other exemplary gases or co-reactants include, but are not limited to, oxidizing agents such as O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof. The disclosed etching compounds / additives and oxidizing agents may be mixed together before being introduced into the reaction chamber.

[0088] Alternatively, the oxidizing agent may be introduced into the chamber continuously, while the etching gas is introduced intermittently. The oxidizing agent may constitute approximately 0.01% v / v to approximately 99.99% v / v of the mixture introduced into the chamber (99.99% v / v represents the introduction of nearly pure oxidizing agent with respect to the continuous introduction option).

[0089] Other exemplary gases from which the disclosed etching compounds and additive gases may be used include cC4F8, C4F8, cC5F8, C5F8, C4F6, CF4, CH3F, CF3H, CH2F2, C3HF7, C3F6, C3H2F6, C3H2F4, C3H3F5, C4HF7, C5HF9, C3F6, C3F8, CF3I, C2F3I, C2F5I, C3F7I, 1-iodoheptafluoropropane (1-C3F7I), 2-iodoheptafluoropropane (2-C3F7I), C3HF7, COS, FNO, FC≡N, CS2, SO2, H2S, SF6, and trans-1,1,1 Examples include ,4,4,4-hexafluoro-2-butene (trans-C4H2F6), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C4H2F6), hexafluoroisobutene (C4H2F6), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C4H2F6), 1,1,2,2,3-pentafluorocyclobutane (C4H3F5), 1,1,2,2-tetrafluorocyclobutane (C4H4F4), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6) or combinations thereof. For example, about 1% v / v to about 25% v / v of the disclosed etching compound may be used, with the remainder being C4F6 or cC4F8. As shown in the following examples, the combination of the disclosed etching compound with a conventional etching gas can result in an increased etching rate while maintaining higher selectivity between the substrate and the layer etched in association with the disclosed etching compound.

[0090] The vapors of the disclosed etching compounds and / or additives are introduced into a reaction chamber containing the substrate and the silicon-containing film. The vapors of the disclosed etching compounds may be introduced into the chamber at flow rates ranging from about 0.1 sccm to about 1 slm. For example, with respect to a 200 mm wafer size, the vapors may be introduced into the chamber at flow rates ranging from about 5 sccm to about 50 sccm. Alternatively, with respect to a 450 mm wafer size, the vapors may be introduced into the chamber at flow rates ranging from about 25 sccm to about 250 sccm. Those skilled in the art will recognize that the flow rates may vary depending on the tool. On the other hand, the vapors of the disclosed additives may be introduced into the chamber at the same pressure and temperature as the disclosed etching compounds, but at a much lower flow rate than the disclosed etching compounds. The vapors of the disclosed additives may be introduced into the chamber at flow rates of less than 20 sccm, preferably less than 15 sccm, more preferably less than 10 sccm, even more preferably less than 5 sccm, and even more preferably less than 2 sccm, under the same conditions as the disclosed etching compounds, such as the same pressure and temperature. The vapors of the disclosed additives can be introduced into the chamber at the same pressure and temperature as the disclosed etching compound, at a flow rate of 0.5 sccm. For example, if SiH2I2 is used as the additive gas and C4F8 is used as the etching gas, SiH2I2 can be introduced at a flow rate of 0.5 sccm and C4F8 at a flow rate of 40 sccm under the same conditions. The ratio of SiH2I2 to C4F8 is 1:80 in terms of flow rate (sccm or moles / second).

[0091] The vapors of the disclosed etching compounds and / or additives can be introduced into the reaction chamber either pre-mixed or separately. It has been found that when the amount of the disclosed additive is added is small (e.g., less than 20 sccm) compared to the etching gas mixed with the disclosed additive, the etching depth is greater than that of the etching gas without the disclosed additive, and the selectivity between the etched layer and the hard mask layer (e.g., SiO2 or ONON layer and hard mask layer) can be increased. In addition, mixing small amounts of the disclosed additive with the etching gas produces clogging-free etching and improves etching profile characteristics such as bowing, CD, and ellipticity.

[0092] The disclosed etching compounds and / or additives may be supplied either in their raw form or in blends with a suitable solvent such as ethylbenzene, xylene, mesitylene, decane, or dodecane. The disclosed etching compounds and additives may be present in the solvent at various concentrations. The vapor form of the disclosed etching compounds and additives can be produced by evaporating the raw or blended solutions of the disclosed etching compounds and additives via a conventional evaporation step such as direct evaporation or bubbling. The raw or blended disclosed etching compounds and additives may be supplied in liquid form to an evaporator to evaporate them before being introduced into the reactor. Alternatively, the raw or blended disclosed etching compounds and additives may be evaporated by passing a carrier gas through a vessel containing the disclosed etching compounds and additives, or by bubbling a carrier gas through the disclosed etching compounds and additives. The carrier gas may include, but is not limited to, Ar, He, N2, Xe, Kr, Ne, and mixtures thereof. The carrier gas and the disclosed etching compounds and additives are then introduced into the reactor as vapors.

[0093] If necessary, the container containing the disclosed etching compounds and additives may be heated to a temperature at which the disclosed etching compounds and additives become liquid phase and have sufficient vapor pressure. The container may be maintained at a temperature in the range of, for example, about 0°C to about 150°C. The line from the bubbler to the etching tool may also be maintained at a temperature above the container temperature. Those skilled in the art will recognize that the container temperature can be adjusted in known ways to control the amount of disclosed etching compounds and additives to be evaporated.

[0094] The disclosed etching compounds and additive gas vapors, as well as additional etching gases, may be mixed before being introduced into the reaction chamber. The additional etching gases may account for approximately 0.01% v / v to approximately 99.99% v / v of the mixture introduced into the chamber.

[0095] The vapor of the disclosed etching compound and additional gases, such as inert gases or co-reactants, are activated by plasma to produce activated etching gases. The plasma decomposes the etching gases into radical forms or ions (i.e., activated etching gases). The plasma may be generated by applying RF or DC (direct current) power. The plasma can be generated in a decoupled plasma etching reactor by RF source power ranging from approximately 25 W to approximately 100,000 W. The plasma may be generated distally or within the reactor itself. The plasma may be generated in dual CCP or ICP mode by RF applied to both electrodes, but is not limited to these. The RF frequency of the plasma may be in the range of 100 kHz to 1 GHz. Different RF sources at different frequencies may be combined and applied to the same electrode. Plasma RF pulses may be used as further bias power to control molecular fragmentation and reactions in the substrate. Those skilled in the art will recognize suitable methods and apparatus for such plasma processing.

[0096] Since the disclosed additives are used with hydrofluorocarbons or fluorocarbons or hydrogen-containing etching compounds, the bias power may be lower compared to etching without the additives. In the disclosed method, by utilizing the additives, the bias power may be at least about 10% lower than when the additives are not used, as shown in the following examples.

[0097] A disclosed method for forming a sidewall passivation layer on a patterned structure of a HAR comprises: i) introducing etchant vapor into a reactor containing a substrate; ii) forming an ion plasma from the etchant in the reactor by applying source power; iii) diffusing ions toward the substrate with or without bias power so that portions of the substrate not covered by a patterned mask layer on the substrate are selectively etched away and a patterned structure of the HAR is formed; and iv) continuing the process for a predetermined time until a sidewall passivation layer is formed on the sidewalls of the patterned structure of the HAR, and then turning off the source power and bias power (if any); wherein the sidewall passivation layer may be a highly conductive sidewall passivation layer.

[0098] In some embodiments, the disclosed method includes forming a highly conductive sidewall passivation layer on a HAR patterned structure. This method includes i) introducing etchant vapor into a reactor containing a substrate; ii) forming an ion plasma from the etchant in the reactor by applying source power; iii) diffusing ions toward the substrate with or without bias power so that portions of the substrate not covered by the patterned mask layer on the substrate are selectively etched away to form a HAR patterned structure; and iv) continuing the process for a predetermined time until a highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structure, and then turning off the source power and low bias power (if any).

[0099] A disclosed method for forming a HAR structure during a HAR etching process in a reaction chamber includes: i) sequentially or simultaneously exposing the substrate to a vapor of an etchant comprising one or more hydrofluorocarbons or fluorocarbon compounds or one or more hydrogen-containing molecules and an additive compound, wherein the substrate has a film disposed thereon and a patterned mask layer disposed thereon; ii) activating a plasma to generate one or more activated hydrofluorocarbons or fluorocarbon compounds or one or more activated hydrogen-containing molecules and an activated additive compound; and iii) allowing an etching reaction to proceed between a film not covered by the patterned mask layer and the activated hydrofluorocarbons or fluorocarbon compounds or the activated one or more hydrogen-containing molecules and the activated additive compound to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure.

[0100] Alternatively, a disclosed method for forming a HAR patterned structure includes: i) sequentially or simultaneously exposing a substrate to vapors of one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and SiH2I2, wherein the substrate has a film disposed thereon and a patterned mask layer disposed thereon; ii) activating a plasma to generate activated one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and activated SiH2I2; and iii) allowing an etching reaction to proceed between a film not covered by the patterned mask layer and the activated one or more fluorocarbon or hydrofluorocarbon compounds or activated one or more hydrogen-containing molecules and activated SiH2I2 to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure. In some embodiments, the disclosed method further includes simultaneously exposing the substrate to a) vapors of one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and b) SiH2I2. In some embodiments, the disclosed method does not include exposing the substrate having a highly conductive sidewall passivation layer to a non-etched sidewall passivation layer deposition step after or between etching steps. In this case, the substrate having the highly conductive sidewall passivation layer deposited thereon does not proceed to the deposition step. On the other hand, in some embodiments, the disclosed method further includes exposing the substrate having a highly conductive sidewall passivation layer to a non-etched sidewall passivation layer deposition step after or between etching steps, wherein the non-etched sidewall passivation layer deposition step does not involve the use of vapors of one or more fluorocarbons or hydrofluorocarbon compounds or one or more hydrogen-containing molecules, and does not involve the use of SiH2I2.In this case, even if a substrate having a highly conductive sidewall passivation layer is exposed to a non-etched sidewall passivation layer deposition step after or between etching steps, SiH2I2 and one or more fluorocarbons or hydrofluorocarbon compounds or one or more hydrogen-containing molecules do not participate in the deposition step.

[0101] Here, the substrate has a film placed thereon and a patterned mask layer placed on the film. The etchant comprises a hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule and an additive compound. The etchant may contain co-reactants and / or an inert gas. After the etchant is introduced into the reactor, it reaches equilibrium. The bias power may be at least 10% lower than when no additive is added to the etchant. The predetermined etching time may be in the range of 1 second to 1000 seconds. The ratio of the additive compound to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule is selected so that the newly formed portion of the sidewall surface is passivated and protected from further etching. The ratio of the additive compound to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule introduced into the reactor may be in the range of 1:200 to 1:10 in flow rate (sccm) under the same conditions (e.g., same temperature and same pressure), preferably varying from 1:200 to 1:50, and more preferably from 1:200 to 1:100. For example, if 0.5 sccm of SiH2I2 is used as an additive and 90 sccm of C4F8 is used as the etching gas, the ratio of SiH2I2 to C4F8 under the same conditions will be 1:180 in terms of flow rate (sccm). Assuming that the additive compound and the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule are ideal gases (PV=nRT), the ratio of the additive compound to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule introduced into the reactor may range from 1:200 to 1:10 in terms of flow rate (moles / second) under the same conditions (e.g., the same temperature and the same pressure), preferably from 1:200 to 1:50, and more preferably from 1:200 to 1:100. Therefore, when 0.5 sccm of SiH2I2 is used as an additive and 30 sccm of C4F8 and 30 sccm of CH2F2 are used as etching gases, the ratio of SiH2I2 to C4F8 under the same conditions will be 1:180 in terms of flow rate (sccm or moles / second).

[0102] The reactor chamber temperature can be controlled by controlling the temperature of the substrate holder or by controlling the temperature of the reactor wall. Apparatus used for heating the substrate is known in the art. The reactor wall is heated to a temperature sufficient to prevent condensation on the wall or on the reactor chamber, especially when a showerhead reactor is used where the substrate temperature is higher than the wall temperature. A non-limiting exemplary temperature range in which the reactor wall can be heated includes about -100°C (liquid nitrogen temperature) to about 500°C, preferably about -100°C (liquid nitrogen temperature) to about 200°C, more preferably about -100°C to about 0°C, even more preferably about 20°C to about 150°C, and even more preferably 20°C to about 110°C. The reactor chamber temperature as used herein also refers to the etching temperature, wafer temperature, substrate temperature, or process temperature.

[0103] Before introducing the etchant into the reactor, the reactor is pumped to a high vacuum in the range of 0.001 mTorr to 100 mTorr, and after the etching process, the reaction may be purged with an inert gas. The pressure in the reaction chamber is maintained at conditions suitable for the etchant or process gas. Here, the etchant or process gas may include hydrofluorocarbon or fluorocarbon etching gas or hydrogen-containing molecules, additives, co-reactants, etc. For example, the pressure in the reactor can be maintained at about 1 mTorr to about 100 mTorr, preferably about 1 mTorr to about 50 mTorr, more preferably about 1 mTorr to about 10 mTorr, and even more preferably about 1 mTorr to about 50 mTorr.

[0104] Etching conditions can change during the etching process. For example, parameters such as gas flow rate, plasma power, pressure, and temperature may be higher or lower during the beginning of the etching process compared to the end of the etching process near the bottom of the hole or trench. Alternatively, different etching gases may be added at different points in the etching process to improve performance, such as by reducing or increasing the polymer deposition rate.

[0105] The disclosed etching process may be a cyclic etching process or a continuous etching process. In a continuous etching process, a protective sidewall passivation layer is deposited and etched simultaneously. A cyclic etching process is a sequential etching process in which etching components or compositions are introduced into the etching chamber sequentially, whereas a continuous etching process is a simultaneous etching process in which etching components or compositions are introduced into the etching chamber simultaneously. In other words, a cyclic etching process is a sequential etching process in which the substrate to be etched is successively exposed to vapors of etchant containing various etching gases or components, while a continuous etching process is a simultaneous etching process in which the substrate to be etched is simultaneously exposed to vapors of etchant containing various etching gases or components. A cyclic etching process may include a deposition step in which plasma power is selected primarily to deposit a thin layer of a protective polymer passivation layer. This passivation layer may be a conductive passivation layer. In the deposition step, source power is applied, which is selected based on the etching gas and the processes involved, and the bias power may be reduced or there may be no bias power. A purge step using an inert gas may be present after the deposition step. An etching step may be present after the purge step. During the etching step, a bias power of a certain range of output can be selected to achieve the appropriate etching rate, selectivity, and damage for the application. The bias power during the etching step may be reduced or there may be no bias power. A purge step using an inert gas may be present after the etching step. This completes the cycle, which is then repeated for an appropriate number of cycles selected based on the etching rate and film thickness. Silicon additives can be added in either the deposition step, the etching step, or both. The inert gas purge step may also include reactive gases to modify the surface, such as oxidizing gases.

[0106] The ALD process refers to a process that generates a film by performing and repeating a series of steps. These steps are: 1) introducing a reactive gas and allowing time for the reactive gas to react with the substrate; 2) purging the reactor with an inert gas; 3) introducing a second reactive gas for sufficient time to react with the substrate; and 4) purging the reactor with an inert gas. In the CVD process, two reactive gases are added simultaneously, and the film is formed by a gas-phase reaction. Plasma can be used to assist the deposition process by forming reactive species, and the plasma may be introduced at any step.

[0107] The disclosed etching method can provide high selectivity for mask layers, photoresists, etch stop layers, and device channel materials, and can not provide profile distortion in contact etching applications for HAR structures such as those having aspect ratios in the range of 1:1 to 200:1, such as DRAM and 3D NAND structures. Alternatively, aspect ratios in the range of 1:1 to 20:1 and 21:1 to 200:1. The disclosed etching method is suitable for etching HAR patterned structures having aspect ratios of 1:1 to 200:1. Alternatively, the disclosed etching method is suitable for etching HAR patterned structures having aspect ratios of approximately 1:1 to approximately 20:1, between approximately 21:1 and approximately 200:1, between approximately 1:1 and approximately 60:1, or between approximately 61:1 and approximately 200:1. The disclosed etching method improves etching profile characteristics such as boeing, CD, and ellipticity, reduces sidewall etching, and reduces the formation of boeing and scalloping. [Examples]

[0108] The following non-limiting embodiments are provided to further illustrate embodiments of the present invention. However, the embodiments are not intended to be comprehensive and nor to limit the scope of the present invention as described herein.

[0109] In the following examples, experiments were conducted using either a commercially available LAM tool 4520XLe 200mm (CCP dual-frequency plasma) or a commercially available AMEC 300mm Primo SSC HD-RIE etcher. To demonstrate reproducibility, each etching test was repeated at least three times. The standard deviation of the mean of the three measurements is shown as error bars in the chart. Subsequently, the polymer composition was investigated by X-ray photoelectron spectroscopy (XPS).

[0110] Example 1: Measurement of the electrical conductivity of a polymer Figures 1-3 show the conductivity of C4H2F6 with and without the additives CH3I, C4F9I, or SiH2I2, respectively, measured on a flat wafer. Current (I)-voltage (V) was measured using a mercury probe. A drop of deionized water was added to the back of the wafer to improve contact resistance. This may help reduce measurement noise at low voltages. Under the same electric field strength, adding iodine molecules to the hydrofluorocarbon increases the measured current through the polymer and lowers the dielectric breakdown voltage. The conductivity of C4H2F6 with the additive is increased compared to the conductivity of C4H2F6 without the additive. See the current difference in Figures 1-3. As shown in Table 1, conductivity was calculated in an electric field of 0.2 MV / cm, and the increase in conductivity at an electric field of 0.2 MV / cm was >10%.

[0111] [Table 3]

[0112] Example 2: ONON hole pattern etching using CH3I as an additive CH3I was added to etching recipes containing C4H2F6 for ONON (i.e., alternating SiO / SiN layers) hole pattern etching on patterned wafers or substrates due to its promising performance on flat thin films (higher selectivity for aC masks and increased polymer conductivity). The patterned wafers have ONON layers on which a hole-patterned amorphous carbon (aC) mask layer is deposited. The etching recipe may also include O2.

[0113] For preliminary screening, four conditions were tested for C4H2F6 / CH3I flow rates: 30 / 10 sccm, 35 / 5 sccm, 40 / 5 sccm, and 40 / 10 sccm. 30 / 10 sccm and 35 / 5 sccm represent the same total gas flow rate. Due to the high polymerizability of CH3I, etch stops were observed in SEM images when the CH3I flow rate was 10 sccm or higher. While the 40 / 5 sccm condition showed improved etching selectivity, further adjustment of the etching recipe is necessary. SEM conditions are as shown in the flow chart: Accel. voltage: 5.0 kV; Emission current: 20 μA; Magnification: ×30.0 k.

[0114] CH3I is highly polymerizable and can clog patterned mask layers, potentially causing further etch stops at flow rates above 10 sccm added to the ONON etching composition. Adding CH3I to the etching recipe shifts the O2 flow rate process window from 68 sccm to 74-76 sccm. For the optimized CH3I recipe: ONON etching rate (ER): 510 nm / min (without CH3I, measured ONON ER is 516 nm / min); ONON vs. aC selectivity: 11.2-12 (without CH3I, ONON vs. aC selectivity is 11.4-12). Figures 4-9 compare ER, selectivity, sidewall bowing, ellipticity, and CD of C4H2F6 with and without the additive CH3I, respectively, due to differences in bias power. Overall, the recipe with CH3I shows less dependence on bias power compared to the recipe without CH3I (ONON etching rate, selectivity, bowing, ellipticity, profile CD).

[0115] More specifically, as shown in Figure 6, at a bias power of 7000W, adding CH3I to the recipe did not show a significant change in the ellipticity of the aC mask holes, and the measured ellipticity was 93% for the recipe without CH3I and 94% for the recipe with CH3I. At a bias power of 5600W, the aC mask profile deteriorated with decreasing bias power in the recipe without CH3I, while little effect was observed in the recipe with CH3I. At a bias power of 4200W, the recipe with CH3I showed improvements in etching performance, including etching rate (ER), selectivity, aC mask ellipticity, and tilt angle. The etching performance is summarized in Table 2.

[0116] [Table 4]

[0117] In summary, the use of the additive CH3I improves surface passivation (also known as the polymer layer) on the etch front and sidewalls of HAR features, and the passivation changes in response to variations in plasma etching conditions (RF power, process time, etc.). Furthermore, adding CH3I as an additive to hydrofluorocarbon etching gases (such as C4H2F6) can reduce bias power by 40% without impairing etching performance such as etching rate, selectivity, ellipticity, and profile CD.

[0118] Example 3: Chemical composition of polymer and electrical conductivity of polymer Substrate: To obtain IV properties solely from the polymer, a low-resistivity Si substrate (less than 0.02 Ω·cm) was used for polymer deposition instead of an SiO2 substrate. To facilitate IV measurements using a mercury probe, the Si substrate was cut into 1-inch x 1-inch coupons.

[0119] Polymer deposition: The same deposition process conditions were used for C4F8, C4H2F6, C4F9I, C4F8+C4F9I, and C4H2F6+C4F9I. The thickness of the deposited polymer was measured using an ellipsometer.

[0120] Ramtool experimental conditions: RF source power: 750W; bias power: 1500W; Ar / etching gas (or gas mixture) / O2: 250 / 15 / 0; etching time: 30 seconds.

[0121] Figure 10 shows various polymer chemical compositions and their electrical conductivity. The measured current (I) ~ voltage (V) was the same as in Example 1. As shown, under the same electric field strength, iodine molecule additives to hydrofluorocarbons induce higher measured currents and lower dielectric breakdown voltages through the polymer. The conductivity at 0.2 MV / cm for various polymers and iodine molecule additives is as follows: C4F9I > C4H2F6 + C4F9I > C4F8 + C4F9I > C4H2F6 > C4F8. Polymers with a higher CC vs. C-Fx / CI ratio (where x is an integer) have higher dielectric breakdown voltages and higher electrical strength.x The bond is considered to contribute to the conductivity of the polymer. Polymers containing many C-C bonds have lower conductivity than polymers containing many C-F x ones.

[0122] Table 3 shows the bond concentration ratios of C-C vs. C-F x / C-I (x is an integer). The bond concentration ratio of C-C:C-F x / C-I is C4F9I < C4F8 + C4F9I < C4F8 < C4H2F6 + C4F9I < C4H2F6 from the lower to the higher. The C-C bond is a nonpolar covalent bond; the C-Fx / C-I bond is a polar covalent bond. The conductivity was calculated at an electric field of 0.2 MV / cm, and the increase in conductivity at an electric field of 0.2 MV / cm was >10%.

[0123]

Table 5

[0124] Due to different conduction mechanisms in various electric fields, it is difficult to show how the chemical composition of the polymer and the electrical conductivity are related to each other. Generally, adding iodine to the polymer increases the conductivity. As a result, without degrading the etching performance such as etching rate, selectivity, ellipticity, profile CD, etc., the bias power may be at least about 10% lower compared to the case without using an additive as shown in Example 2.

[0125] Example 4: Oxide hole pattern etching using SiH2I2, C4F6 baseline vs. 7000W / 20W process bias power The oxide hole pattern was a 3-μm thick PETEOS (PECVD TEOS) SiO2 layer deposited on a Si substrate. An a-C mask layer was deposited on the SiO layer. Its thickness was measured to be approximately 641 nm. The a-C mask layer was patterned with holes of approximately 87°. The diameter of each hole was 140 - 160 nm. The CD of the holes was approximately 164 nm. The C4F6 baseline was used to compare with an etching process using SiH2I2.

[0126] The SiH2I2 etching gas was introduced as a mixture with Ar by bubbling Ar through a liquid container of SiH2I2 to etch the SiO2 layer on the patterned a-C mask layer. The flow rate of the mixture of SiH2I2 and Ar was controlled by an Ar mass flow controller (MFC). In all the processes carried out, the etching time was 300 seconds, the wafer temperature was 20 °C, and the etching chamber pressure was 20 mTorr. Various etching parameters in the etching process are listed in Table 4. Here, DC represents the duty cycle, and the RF power expressed as "700 / 200" means that the RF power cycles between 700 W and 200 W at the described frequency (Fr) of 500 Hz. The ratio of SiH2I2 to C4F6 is 1:64 in terms of flow rate (sccm and / or mol / second).

[0127]

Table 6

[0128] Table 5 shows the etching results for the C4F6 baseline vs. SiH2I2 process. Using SiH2I2 etching gas as an additive gas increased the etching rate of SiO2 by 5%. The etching rate of the aC mask layer decreased (-33%) with the introduction of SiH2I2 etching gas, resulting in a 57.4% improvement in SiO2:aC selectivity. More boeing was observed with SiH2I2, which is mainly attributed to improved storage stability of the aC mask layer. Furthermore, using SiH2I2 etching gas as an additive gas increased the etching depth by 5.3%, while etching of the mask layer was less than without the SiH2I2 additive gas (44.8%).

[0129] [Table 7]

[0130] Example 5: Oxide hole pattern etching using SiH2I2, C4F6 baseline vs. 5600W / 20W process bias power The oxide hole pattern used in Example 5 was the same as that used in Example 4. Various etching parameters in the etching process are shown in Table 4. The ratio of SiH2I2 to C4F6 was 1:64 in flow rate (sccm and / or moles / second). The etching results with a 5600W process bias power using C4F6 baseline vs. SiH2I2 are shown in Table 6. All other etching parameters were the same as in Example 4, except that the bias power was 5600W. At a bias power of 5600W, the etching rate of SiO2 decreased in both the C4F6 baseline and the 5600W process bias power using SiH2I2. The etching process using SiH2I2 showed an increased ER of SiO2 (+6.6%), a decreased ER of the aC mask (-12%), and an improvement of approximately 22.2% in the selectivity of SiO2 vs. aC. Boeing was observed in both processes, but the addition of SiH2I2 slightly improved the boeing. Furthermore, using SiH2I2 etching gas as an additive gas increased the etching depth by 6.6%, while etching of the mask layer was less than when SiH2I2 was not used (8.1%).

[0131] [Table 8]

[0132] Example 6: Oxide hole pattern etching using SiH2I2, C4F6 baseline vs. 4200W / 20W process bias power The oxide hole pattern used in Example 6 was the same as that used in Example 4. Various etching parameters in the etching process are shown in Table 4. The ratio of SiH2I2 to C4F6 was 1:64 in flow rate (sccm and / or moles / second). The etching results with a 4200W process bias power using C4F6 baseline vs. SiH2I2 are shown in Table 7. All other etching parameters were the same as in Example 4, except that the bias power was 4200W. At a bias power of 4200W, the ER of the oxide decreased significantly (over 20%), with or without SiH2I2. The ER of SiO2 increased compared to the baseline (+4.8%), and the ER of the aC mask decreased, resulting in an approximately 11.5% improvement in the selectivity of SiO2:aC. Similar profiles such as maximum CD, bottom CD, and bowing were observed in the etching process with or without SiH2I2. Furthermore, using SiH2I2 etching gas as an additive gas increased the etching depth by 4.5%, while etching of the mask layer was less than when SiH2I2 was not used (4.9%).

[0133] [Table 9]

[0134] Example 7: Polymer property evaluation using SiH2I2 The polymer was deposited on a flat aC film using a 300 mm plasma etcher at a chamber pressure of 20 mTorr and a wafer temperature of 20°C, with a bias power of 7000 W / 200 W, source power of 700 W / 200 W, duty cycle of 70%, gas flow rates of 25 sccm of C4F8, 0.5 sccm of SiH2I2, and 150 sccm of Ar. The SiH2I2 to C4F6 ratio was 1:50 in terms of flow rate (sccm and / or moles / second). XPS analysis of the polymer revealed a composition of 64% carbon, 26% fluorine, 8% oxygen, 2% silicon, and 0.3% iodine. This indicates that when SiH2I2 is mixed with fluorocarbon gas on the aC mask surface, a polymer containing silicon and iodine is deposited.

[0135] Example 8: Polymer property evaluation using SiH2I2 The polymer was deposited on a flat SiO2 film using a 300 mm plasma etcher at a chamber pressure of 20 mTorr and a wafer temperature of 20°C, with a bias power of 7000 W / 200 W, source power of 700 W / 200 W, duty cycle of 70%, gas flow rates of 25 sccm of C4F8, 0.5 sccm of SiH2I2, and 150 sccm of Ar. The SiH2I2 to C4F8 ratio was 1:50 in terms of flow rate (sccm and / or moles / second). High-resolution XPS analysis of the polymer showed that it contained carbon, fluorine, silicon, iodine, and oxygen. For silicon, the main bond formations were Si-C bonds and small amounts of Si-F bonds. Iodine was detected as ICO bonds. This indicates that when SiH2I2 is mixed with fluorocarbon gas on an SiO2 surface, a polymer containing silicon and iodine is deposited.

[0136] Example 9: Measurement of the electrical conductivity of a polymer. The polymer was deposited using a 300 mm plasma etcher with a bias of 1000 W / 200 W, a source of 950 W / 200 W, a duty cycle of 70%, and 4 sccm of C4F8, 4 sccm of C4F6, 5 sccm of CH2F2, 15 sccm of O2, and 150 sccm of Ar, with or without 0.5 sccm of SiH2I2. The ratio of SiH2I2 to the total of C4F8, C4F6, and CH2F2 was 1:26 in flow rate (sccm and / or moles / second). Conductivity was measured by the method described in Example 1. The conductivity of the polymer without SiH2I2 was found to be approximately 1 E-10 (A) at 100 V, and the conductivity of the polymer with SiH2I2 was found to be approximately 6 E-10 (A) at 100 V. This indicates that polymers deposited using various standard fluorocarbon and hydrofluorocarbon gases increase with the addition of SiH2I2.

[0137] In summary, the addition of SiH2I2 increases the SiO2 etching rate by 5%. The etching rate of the aC mask decreases with the addition of SiH2I2, and the selectivity of SiO2 to aC improves by approximately 57.4%. At a bias power of 5400W, the oxide etching rate decreases in both recipes. Adding SiH2I2 increases the ER of SiO2 (+6.6%), decreases the ER of the aC mask, and improves the selectivity of SiO2 to aC by approximately 22.2%.

[0138] The oxide etching rate decreases at low plasma bias powers, such as 5400W and 4200W. Processes using SiH2I2 have been shown to increase the etching rate of oxide holes and improve selectivity for aC masks. Adding SiH2I2 allows etching of oxide holes at a similar but lower bias power (e.g., 5400W) as the baseline. Boeing was observed under both conditions. Polymers deposited on aC masks and SiO2 planar films using fluorocarbons such as C4F8 and the additive SiH2I2 are composed of carbon, fluorine, oxygen, silicon, and iodine, and Si-C, Si-F, and ICO bonds are formed within the polymer.

[0139] Virtual Example 1: Etching of SiO2 or ONON hole patterns using SiH2I2 The SiO2 or ONON hole pattern is etched using 30 sccm of C4F8, 30 sccm of C4F6, 30 sccm of CH2F2, and 0.5 sccm of SiH2I2. The ratio of SiH2I2 to the sum of C4F8, C4F6, and CH2F2 is 1:180 in flow rate (sccm and / or moles / second). The SiO2 or ONON hole pattern may be a 3 μm thick PETEOS (PECVD TEOS) SiO2 layer or alternating SiO / SiN layer deposited on a Si substrate. Similar to the pattern used in Example 4, an aC mask layer was deposited on the SiO layer or alternating SiO / SiN layer. The aC mask layer was patterned with holes at approximately 87°. The diameter of each hole was 140-160 nm. The CD of the holes was approximately 164 nm. O2 and Ar are added appropriately, for example, 40 sccm of O2 and 150 sccm of Ar. The plasma conditions are the same as those described in Table 4. Using SiH2I2 etching gas as an additive gas increases the etching rate and etching depth of SiO2 or ONON, improves the selectivity of SiO2 vs. aC or ONON:aC, forms a conductive passivation layer, and creates an etching profile with little to no bowing and clogging.

[0140] It will be understood that many additional modifications in the details, materials, steps, and arrangement of the parts described and illustrated herein to illustrate the nature of the present invention can be made by those skilled in the art within the principles and scope of the invention set forth in the appended claims. Accordingly, the present invention is not intended to be limited to the specific embodiments shown above and / or in the appended drawings.

[0141] Embodiments of the present invention are shown and described herein, but can be modified by those skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are merely exemplary and not limiting. Many variations and modifications of the compositions and methods are possible and fall within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is limited only by the claims, which include all equivalents of the subject matter of the claims.

Claims

1. A method for forming a high aspect ratio (HAR) structure in a substrate within a reaction chamber during a high aspect ratio (HAR) etching process, The substrate is sequentially or simultaneously exposed to a vapor of an etchant containing one or more hydrofluorocarbons or fluorocarbon compounds or one or more hydrogen-containing molecules and an additive compound, wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; Here, the additive compound comprises silicon and iodine and is given by the following formula: SiR １ R ２ I ｘ F （２－ｘ） (where x = 1 to 2; R １ and R ２ are each independently selected from H, C １ to C １０ linear, branched or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl groups; R １ and R ２ may be linked to form a cyclic group) Having; Activating plasma to generate one or more activated hydrofluorocarbons or fluorocarbon compounds or one or more activated hydrogen-containing molecules and activated additive compounds; and The process involves proceeding with an etching reaction between the film not covered by the patterned mask layer, the activated hydrofluorocarbon or fluorocarbon compound or the activated one or more hydrogen-containing molecules, and the activated additive compound to selectively etch the film from the patterned mask layer, thereby forming the HAR patterned structure; A method that includes this.

2. The step further includes introducing an oxidizing agent into the reaction chamber, wherein the oxidizing agent is O ２ , O ３ CO, CO ２ NO, N ２ O, NO ２ , H ２ O, H ２ O ２ , COS, SO ２ The method according to claim 1, selected from, and combinations thereof.

3. The process further includes the step of introducing an inert gas into the reaction chamber, wherein the inert gas is He, Ar, Xe, Kr, Ne, and N ２ The method according to claim 1, selected from the group consisting of the following.

4. The method according to claim 1, wherein a highly conductive sidewall passivation layer is formed on the sidewall of the HAR patterned structure.

5. The method according to claim 4, wherein the conductivity of the highly conductive sidewall passivation layer formed using the activated hydrofluorocarbon or fluorocarbon compound or the activated hydrogen-containing molecule and the activated additive compound is at least about 10% higher than the conductivity of the highly conductive sidewall passivation layer formed using the activated hydrofluorocarbon or fluorocarbon compound or the activated hydrogen-containing molecule without the addition of the activated additive compound.

6. The one or more hydrofluorocarbons or fluorocarbon compounds mentioned above are CF ４ ,CH ３ F, C ２ F ６ , C ３ F ８ , C ２ HF ５ , C ５ F ８ , C ６ F ６ , C ４ F ６ , C ４ F ８ , C ４ H ２ F ６ CHF ３ ,CH ２ F ２ , or C １ ~C ５ A fluorocarbon and hydrofluorocarbon compound containing nitrogen, oxygen, iodine, or sulfur, comprising saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons, or combinations thereof, wherein one or more hydrogen-containing molecules are H ２ The method according to claim 1, wherein the gas is a halogen-containing acidic gas that includes HCl, HBr, HI, or a combination thereof.

7. The method according to claim 1, wherein the ratio of the additive compound to the hydrofluorocarbon or fluorocarbon compound or the hydrogen-containing molecule is in the range of 1:200 to 1:10 in flow rate (moles / second) at the same temperature and pressure.

8. The aforementioned additive compound is SiH ２ I ２ The method according to any one of claims 1 to 7. 。

9. The aforementioned additive compound is as follows: 【Chemistry 1】 The method according to any one of claims 1 to 7, wherein the silicon-containing compound is selected from the following.

10. A method for forming a HAR patterned structure, The substrate is made of one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and SiH ２ I ２ A step of sequentially or simultaneously exposing the substrate to vapors thereof, wherein the substrate has a film disposed thereon and a patterned mask layer disposed thereon; The plasma is activated, and one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and activated SiH ２ I ２ The steps to generate and A membrane not covered by a patterned mask layer and one or more activated substances. Fluorocarbon or hydrofluorocarbon compounds or the activated hydrogen-containing molecules and the activated SiH ２ I ２ The step of proceeding with an etching reaction between the two to selectively etch the film from the patterned mask layer, thereby forming the HAR patterned structure; A method that includes this.

11. A step of introducing an oxidizing agent into a reaction chamber, wherein the oxidizing agent is O ２ , O ３ CO, CO ２ NO, N ２ O, NO ２ , H ２ O, H ２ O ２ , COS, SO ２ , and steps selected from combinations thereof, A step of introducing an inert gas into the reaction chamber, wherein the inert gas is He, Ar, Xe, Kr, Ne, and N ２ The method according to claim 10, further comprising a step selected from the group consisting of the following:

12. The method according to claim 10, wherein a highly conductive sidewall passivation layer is formed on the sidewall of the HAR patterned structure.

13. The activated fluorocarbon or hydrofluorocarbon compound or the activated hydrogen-containing molecule, and the activated SiH ２ I ２ The conductivity of the highly conductive sidewall passivation layer formed using is the activated SiH ２ I ２ The method according to claim 12, wherein the conductivity of the highly conductive sidewall passivation layer formed using one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more activated hydrogen-containing molecules is at least about 10% higher than that of the highly conductive sidewall passivation layer formed using the activated one or more hydrogen-containing molecules without the addition of the activated fluorocarbon or hydrofluorocarbon compound.

14. The method according to claim 13, wherein the substrate having the highly conductive sidewall passivation layer is not exposed to a non-etched sidewall passivation layer deposition step after or between etching steps.

15. The process includes, after or between etching steps, exposing the substrate having the highly conductive sidewall passivation layer to a non-etched sidewall passivation layer deposition step, wherein the non-etched sidewall passivation layer deposition step does not involve the use of vapors of one or more fluorocarbons or hydrofluorocarbon compounds or one or more hydrogen-containing molecules, and SiH ２ I ２ The method according to claim 13, which does not involve the use of the following:

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