Sidewall Passivation Layer During High Aspect Ratio Plasma Etching and Method of 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] A method of forming a passivation layer on sidewalls using an etching gas as an additive by doping silicon, iodine, and / or carbon elements during high aspect ratio (HAR) plasma etching and / or introducing a cyclic, aromatic, heterocyclic chemical structure is disclosed, particularly a method of forming a highly conductive sidewall passivation layer.

Background Art

[0002] For over 50 years, due to Moore's Law, semiconductor manufacturers have been continuously reducing the feature size of devices in order to improve the speed and capabilities of transistors / chips while maintaining a cost advantage over competing companies. This has posed new challenges to the manufacturing process to successfully meet the ever-decreasing feature sizes and dramatically increasing aspect ratio requirements. For example, the manufacture of three-dimensional gate stack NAND flash memory (3D-NAND) requires the ability to etch small hole features in 90+ NAND layers with an aspect ratio exceeding 40. It is necessary to etch more than 1 trillion holes per wafer using ultra-high aspect ratio (HAR) etching.

[0003] The vertical isotropy of the etched features is obtained by ion transport during plasma sheath formation. In principle, positive and negative particles should follow the same trajectory within the hole and equalize the charge at the bottom of the HAR hole. However, due to the electron shading effect, charge accumulates at the bottom of the HAR mask pattern, which may lead to incomplete etching, bowing, twisting, and variation in the critical dimension (CD) between the top and bottom of the HAR stack. Therefore, many efforts have been made and are continuing in the industry to remove or minimize sidewall charging during HAR etching in order to improve the etching profile and CD control.

[0004] High aspect ratio plasma etching is a complex process that utilizes a number of different standard fluorocarbon etching gases to control etching rate, selectivity to the mask layer, and etching profile. Sidewall passivation layers, such as polymers, are important for controlling the profile and reducing bowing. Polymers deposited by fluorocarbon gases are also useful for protecting the mask layer from the impact of Ar+ ions and oxygen radicals, to which an inert gas and / or an oxidizing agent are often added.

[0005] Contact hole distortion is known to be caused by asymmetric charging of the contact hole sidewalls, which changes the local electric field within the contact hole and the direction 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, the ellipticity has been used to evaluate mask degradation. A high (near 100%) ellipticity can help avoid twisting of the HAR holes and reduce distortion of the etching profile.

[0006] The following are some examples of methods that have been used to adjust the characteristics of the passivation layer during HAR etching. As a natural result, 1) the gas / chemical supply settings to the process chamber become complex, 2) the uniformity of the passivation layer at the top and bottom of the HAR features becomes insufficient, 3) problems with chamber cleaning - some metal-containing polymer deposits on the chamber walls, which are difficult to completely remove, etc. occur.

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

[0008] U.S. Patent No. 7846846B2 by Bera et al. discloses a method of etching HAR contact openings while preventing bowing and bending of the etching profile by forming a highly conductive thin film on the sidewalls of each contact opening. The conductivity of the thin film on the sidewalls is enhanced by ion bombardment periodically performed during the etching process. The etchant is a fluorocarbon / fluorohydrocarbon gas containing at least one of C2F4, C4F6, CH2F2, or C4F8, C1-C5 saturated or unsaturated linear, branched, cyclic hydrofluorocarbons, such as C4H2F6, CHF3, CH2F2, or a combination thereof.

[0009] U.S. Patent Nos. 9,543,158 and 10,170,324 to Nikhil et al. disclose various methods, apparatuses, and systems for forming concave features in a dielectric material on a substrate. In some cases, a protective coating is deposited using plasma-assisted atomic layer deposition (ALD), modified plasma-assisted ALD, or plasma-assisted chemical vapor deposition (CVD). The etching chemistry is a combination of fluorocarbon and oxygen, C4F6, C4F3, N2, CO, CF4, and O2. The protective layer is a ceramic-based material or an organic polymer. When 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 y)For silicon-containing materials such as, the reactant may be, for example, silane, halosilane, or aminosilane. The halosilane contains at least one halogen group and may or may not contain a hydrogen group and / or a carbon group. Examples of halosilanes are iodosilane, bromosilane, chlorosilane, and fluorosilane. Although halosilanes, particularly fluorosilanes, may form reactive halide species capable of etching silicon materials, in the specific embodiments described herein, there is no silicon-containing reactant when the plasma is irradiated. In certain examples, the silicon-containing reactant is selected from the group consisting of SiCl4, SiH4, SiF4, SiBr4, and combinations thereof. Deposition reactions such as cyclic ALD or 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 that is silicon oxide. In some other cases, the silicon-containing precursor can react with a relatively weak oxidizing agent. U.S. Patent No. 9,543,158 describes, in one example, a method for depositing a protective sidewall coating in which the first reactant is SiCl4, which is supplied in argon as a carrier gas. SiCl4 can be supplied at a rate of about 20 sccm, argon can be supplied at a rate of about 100 sccm, and a second reactant such as an oxidizing agent is flowed in a separate step such as COS at a rate of about 30 sccm together with the carrier gas. No fluorocarbon gas was flowed during the deposition process. Analysis of the film showed 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. 10,170,324 describes one example using BCl3, N2, and H2, where BCl3 is supplied at a flow rate of about 50 - 1000 sccm, N2 is supplied at a flow rate of about 50 - 1000 sccm, and H2 is supplied at a flow rate of about 50 - 1000 sccm.

[0010] U.S. Patent No. 10,361,092 discloses adding a metal-containing component to an etching process together with a fluorocarbon etching gas, where the metal-containing component includes at least one metal selected from 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. 10,741,407 discloses a method of adding the 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. 2021 / 0242032 discloses a method of depositing a metal-containing protective film on the sidewalls of features using a cyclic process of etching and deposition where the protective film is 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 of etching features in a silicon oxide-containing film and forming a sidewall passivation layer of passivation containing tungsten and carbon by adding a W (tungsten)-containing gas, such as WF6, WF5Cl, WBr6, W(CO)6, WCl6, to a carbon-containing passivation gas such as a hydrocarbon, fluorohydrocarbon, or fluorocarbon gas. It is expected that the addition of W improves the etching resistance of the sidewall passivation layer.

[0014] The HAR etching process has become an important process for memory devices. Ion energy control by increasing the effective bias power of HAR features has been continuously improving. Considerable efforts have been made to increase the ion energy to overcome the charge accumulation at the etching front in the HAR hole. Based on the trend of bias power over the past few years, the power currently required would exceed 20 kW. As the bias power increases, many issues arise. Prevention of arc discharge, effective cooling, and the power supply system are all important for achieving high power capabilities. Furthermore, since neutral species move only by diffusion through the holes, it becomes difficult to supplement the neutral flux as the aspect ratio increases.

Summary of the Invention

Problems to be Solved by the Invention

[0015] Therefore, during HAR plasma etching, it is required to realize a passivation layer, particularly a highly conductive sidewall passivation layer in HAR plasma etching.

Means for Solving the Problems

[0016] A method of forming a HAR structure during a high aspect ratio (HAR) etching process on a substrate in a reaction chamber is disclosed, the method comprising: sequentially or simultaneously exposing the 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 the 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 Advancing 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 an activated additive compound to selectively etch the film from the patterned mask layer, thereby forming a HAR-patterned structure; including. The disclosed method may include one or more of the following aspects: · Further including 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; · Mixing an etching compound, an additive, and an oxygen-containing gas to produce a mixture before introducing them into the chamber; · Introducing the etching compound and the additive separately from the oxygen-containing gas; · Continuously introducing the oxygen-containing gas and introducing the iodine-containing etching compound; · The oxygen-containing gas occupies from about 0.01% v / v to about 99.9% v / v of the total volume of the etching compound, the additive, and the oxygen-containing gas; · The oxygen-containing gas occupies from about 0.01% v / v to about 10% v / v of the total volume of the etching compound, the additive, and the oxygen-containing gas; · Further including the step of introducing an inert gas into the reaction chamber, the inert gas being selected from the group consisting of He, Ar, Xe, Kr, Ne, and N2; · The inert gas is Ar; · The inert gas is N2; · Mixing an etching compound, an additive, and an inert gas to produce a mixture before introducing them into the chamber; · Introducing the etching compound and the additive separately from the inert gas; · Continuously introducing the inert gas and introducing the etching compound and the additive in pulses; · The inert gas occupies from about 0.01% v / v to about 99.9% v / v of the total volume of the etching compound, additive, and vapor of the inert gas; · The inert gas occupies from about 90% v / v to about 99.9% v / v of the total volume of the etching compound, additive, and vapor of the inert gas; · The patterned structure is a 3D NAND aperture; · The patterned structure is a 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; · The plasma-activated hydrofluorocarbon or fluorocarbon compound and the activated additive compound react with the film to form volatile by-products; · The volatile by-products are removed from the reaction chamber; · The sidewall passivation layer is formed on the sidewalls 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; · The highly conductive sidewall passivation layer is formed on the sidewalls of the HAR-patterned structure; · The conductivity of the highly conductive sidewall passivation layer formed using one or more activated hydrofluorocarbon or fluorocarbon compounds or one or more activated hydrogen-containing molecules 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 one or more activated hydrogen-containing molecules without adding the activated additive compound; · Due to the conductive state of the polymer passivation layer, the accumulation of charges along the sidewalls decreases, and by bleeding off the charges, the twisting of the HAR structure such as holes is prevented, ensuring appropriate control of CD variation in a state where the bias power is not at a low level; · The hydrogen-containing etching gas is a halogen-containing acidic gas containing H2, methane, or HCl, HBr, HI, or a combination thereof; · The hydrogen-containing etching gas 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; · The halogen-containing acidic gas contains HCl, HBr, HI, or a combination thereof; · The hydrofluorocarbon or fluorocarbon compound is CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, C4H2F6, CHF3, CH2F2, or a saturated or unsaturated linear, branched, cyclic hydrofluorocarbon of C1 - C5, or a combination thereof, a fluorocarbon and hydrofluorocarbon compound containing nitrogen, oxygen, iodine, or sulfur, and one or more hydrogen-containing molecules are H2 or a halogen-containing acidic gas containing HCl, HBr, HI, or a combination thereof; · The hydrofluorocarbon or fluorocarbon compound contains CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, a saturated or unsaturated linear, branched, cyclic hydrofluorocarbon of C1 - C5, such as C4H2F6, CHF3, CH2F2, or a combination thereof; · The hydrofluorocarbon or fluorocarbon compound is C4H2F6; · The hydrogen-containing molecule is H2; · The hydrogen-containing molecule is a halogen-containing acidic gas containing HCl, HBr, HI, or a combination thereof; · The halogen-containing acidic gas contains HCl, HBr, HI, or a combination thereof; ·The additive compound has the following formula and contains a silicon element, an iodine element, and / or a carbon element: 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 to 10; x = 1 to 2; y = 1 to 3; z = 1 to 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 to 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] Also disclosed is a method for forming a HAR patterning structure, the method comprising: Exposing the substrate sequentially or simultaneously to the vapor 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 on the film; Activating the plasma to generate one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more activated hydrogen-containing molecules and activated SiH2I2; and A step of allowing an etching reaction to proceed 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; is included. The disclosed method may include one or more of the following aspects: · Further including a step of introducing an oxidizing agent into the reaction chamber, wherein the oxidizing agent is selected from O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof; · Further including a step of introducing an inert gas into the 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 sidewalls of the HAR-patterned structure; · 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 and activated SiH2I2 is at least about 10% higher than 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 without adding activated SiH2I2; · The HAR-patterned structure formed on the film has an aspect ratio of about 1:1 to about 200:1; · further comprising introducing additional etching gas into the reaction chamber, the additional etching gas being selected from the group consisting of 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, F-C≡N, CS2, SO2, SF6, trans-1,1,1,4,4,4-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), and combinations thereof; · the film is a silicon-containing film comprising O and / or N and optionally 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 fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and b) SiH2I2; · the method does not include exposing a substrate having a highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step after or between etching steps; · the method includes exposing a substrate having a highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step after or between etching steps; · The non-etching sidewall passivation layer deposition step does not include the use of one or more fluorocarbons or hydrofluorocarbons or the vapor of one or more hydrogen-containing molecules, and does not include the use of SiH2I2; · The non-etching sidewall passivation layer deposition step does not include the use of SiH2I2.

[0018] Notation and nomenclature In the following detailed description and claims, generally, a number of abbreviations, symbols, and terms well known in the art are utilized and include the following:

[0019] As used herein, the indefinite article "a" or "an" means one or more.

[0020] As used herein, "about" or "substantially" or "approximately" in the text or in the claims means ±10% of the recited value.

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

[0022] The term "wafer" or "patterned wafer" refers to a wafer having any existing stack of films including a silicon-containing film on a substrate and a patterned hardmask layer on any existing stack of films including a silicon-containing film formed for pattern etching.

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

[0024] The term "pattern etching" or "patterned etching" refers to etching a non-flat structure such as a stack of silicon-containing films under a patterned hard mask layer.

[0025] As used herein, the terms "etch" or "etching" mean removing material by using an etching compound and / or plasma, by ion bombardment, remote plasma, or a chemical vapor reaction between an etching gas and a substrate, and refer to an isotropic etching process and / or an anisotropic etching process. An isotropic etching process involves a chemical reaction between an etching compound and a substrate, and a portion of the material on the substrate is removed. This type of etching process includes chemical dry etching, vapor phase chemical etching, thermal dry etching, etc. An isotropic etching process generates a lateral or horizontal etching profile on the substrate. An isotropic etching process generates a recess or a horizontal recess on the sidewall of an aperture pre-formed on the substrate. An anisotropic etching process includes a plasma etching process (i.e., a dry etching process) in which a chemical reaction is accelerated in the vertical direction by ion bombardment, and as a result, a vertical sidewall perpendicular to the substrate is formed along the edge of the masked feature (Manos and Flamm, Thermal etching an Introduction, Academic Press, Inc. 1989 pp. 12-13). The plasma etching process generates a vertical etching profile on the substrate. The plasma etching process generates on the substrate vertical vias, apertures, trenches, channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, slit etching, self-aligned contacts, self-aligned vias, super vias, etc.

[0026] The term "mask" refers to a layer resistant to etching. The mask layer can be disposed on top of the layer to be etched. The mask layer also refers to a hard mask layer. The mask layer can be an amorphous carbon (a-C) layer, a doped a-C layer, a photoresist layer, an antireflection layer, an organic planarization layer, and combinations thereof. The mask layer can also be a silicon layer such as poly Si, metal oxides such as Ti, Al, Zr, Hf, oxides, and combinations thereof.

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

[0028] The term "etch stop" means the layer below the layer being etched that protects the underlying layer.

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

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

[0031] The terms "via", "aperture", "trench", and "hole" may be used interchangeably and generally mean an opening in the interlayer insulator.

[0032] The term "low bias power" or "reduced bias power" refers to a bias power lower than 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 and that improves the etching characteristics 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 of measuring mask degradation. In the context of etching, the ellipticity of an etched hole is estimated by (width of the short hole / width of the long hole) * 100% for simplicity; thus, a perfect circular ellipticity 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 making rapid and non-destructive contact with a sample for electrical property evaluation. When the contact between mercury and the sample is ohmic (non-rectifying), a current-voltage measuring instrument can be used to measure resistance, leakage current, or current-voltage characteristics. Resistance can be measured in a bulk sample or a thin film. The thin film can be composed of any material that does not react with mercury. The diameter of the mercury contact of the mercury probe used herein is 760 um.

[0037] As used herein, the term "conductivity" is the reciprocal of electrical resistivity and represents the ability of a material to conduct current. The unit of electrical conductivity used herein 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, and is calculated as 2.14×10 -9 S / cm.

[0039] It should be noted that in this specification, the terms "film" and "layer" can be used interchangeably. It is understood that a film can correspond to a layer or be related to a layer, and that a layer may also be referred to as a film. Further, those skilled in the art will recognize that when the terms "film" or "layer" are used in this specification, they mean the thickness of some material applied or extended on a surface, and that the surface can range from as large as the 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" can 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 can correspond to or be related to the etching gas or etchant or process gas, and that the etching gas or etchant or process gas can refer to the etching compound.

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

[0042] As used herein, the term "duty cycle (DC)" refers to the ratio of the time during which a plasma signal is maintained at high power. This is typically expressed as a ratio of periods. For example, in the case of DC: 70%, radio frequency (RF) power at 2M: 7000W and 200W respectively, and Fr: 500 Hz, the plasma signal becomes 7000W (i.e., high power) for 70% of the time in one cycle and 200W (i.e., low power) for 30% of the time, meaning that the plasma signal switches between 7000W and 200W at a cycle speed of 500 Hz. (500 cycles per second).

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

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

[0045] Note that silicon-containing films such as SiN and SiO are listed throughout the specification and claims without indicating their appropriate stoichiometry. The silicon-containing film may include a pure silicon (Si) layer such as crystalline Si, polycrystalline silicon (p-Si or polysilicon), or amorphous silicon; a silicon nitride (Si k N l ) layer; a silicon oxide (Si n O m ) layer; or a mixture thereof, where k, l, m, and n are all in the range of 0.1 to 6. Preferably, the silicon nitride is Si k N l where k and I are each in the range of 0.5 to 1.5. More preferably, the silicon nitride is Si3N4. In this specification, SiN in the following description refers to Si k N lIt may be used to represent a 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" as 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) (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 do not necessarily have to be identical. Further, unless otherwise specified, it should be understood that the values of the R groups are independent of each other when used in different formulas.

[0047] Ranges may be expressed herein as from about a particular value and / or to about another particular value. When such a range is expressed, another embodiment is to be understood as within the all combinations within the range, from a particular value and / or to another particular value.

[0048] References herein to “one embodiment” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. Appearances of the phrase “in one embodiment” in various places in this specification are not necessarily all referring to the same embodiment, and another or alternative embodiment is not necessarily mutually exclusive of other embodiments. The same applies to the term “implementation”.

[0049] For a further understanding of the nature and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings. In the drawings, like elements are given the same or similar reference numerals.

Brief Description of the Drawings

[0050]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0051] In a high aspect ratio (HAR) plasma etching process, a method of forming a sidewall passivation layer on sidewalls using an etching gas as an additive by doping with Si element, I element, and / or C element is disclosed. The disclosed method uses an etching compound or etchant containing a hydrofluorocarbon / fluorocarbon etching gas or a hydrogen-containing molecule and an additive or additive chemical substance in the HAR plasma etching process to form a sidewall passivation layer by doping with Si element, I element, and / or C element. 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, ellipticity, etc. are improved. The sidewall passivation layer is useful for reducing sidewall etching and reducing the formation of bowing and scallop. More specifically, by applying an additive in an amount less than that of the hydrofluorocarbon / fluorocarbon etching gas or hydrogen-containing molecule, HAR plasma etching profile characteristics such as bowing, CD, ellipticity, etc. are improved. In some embodiments, the ratio of the flow rate (sccm and / or mol / sec) of the additive compound to the hydrofluorocarbon / fluorocarbon etching gas or hydrogen-containing molecule may range from 1:200 to 1:10 under the same conditions.

[0052] The disclosed sidewall passivation layer may be a highly conductive sidewall passivation layer. Accordingly, the disclosed method of forming a sidewall passivation layer on a sidewall includes a method of forming a highly conductive sidewall passivation layer on a sidewall. The disclosed method is a method of forming a highly conductive sidewall passivation layer on a sidewall by doping Si element, I element, and / or C element in an HAR plasma etching process and using an etching gas as an additive. The disclosed method uses an additive or an additive chemical substance in an HAR plasma etching process to form a highly conductive sidewall passivation layer by doping Si element, I element, and / or C element. The highly conductive sidewall passivation layer may be a polymer passivation layer or a fluorocarbon layer. Depending on the conductive state of the polymer passivation layer, the accumulation of charges along the sidewall is reduced, the twisting of HAR structures such as holes is prevented by bleeding off the charges, and appropriate control of CD variation in a state where the bias power is not at a low level is ensured. By applying an additive, HAR plasma etching profile characteristics such as bowing, CD, and ellipticity are improved. The highly conductive sidewall passivation layer is useful for reducing sidewall etching and reducing the formation of bowing and scallops. By applying an additive, in some embodiments, the bias power can be at least about 10% lower than when no additive is used. In some embodiments, applying an additive may eliminate the need for bias power. The disclosed etching compound that uses an etching gas as an additive by doping Si element, I element, and / or C element may be less dependent on bias power or not dependent on bias power compared to an etching compound without an applied additive.

[0053] The disclosed method can be considered low-bias energy plasma etching because it has minimized sidewall charges and can reduce the plasma bias power that is considered necessary for reactive ions to reach the bottom of the HAR trench. Additionally, the disclosed etching gas or process gas or etchant containing additives does not contain elements that are difficult to clean, thereby minimizing the 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 H2, methane, or a halogen-containing acidic gas including HCl, HBr, HI, or a combination thereof, and an additive gas. The predetermined time can range from 0 seconds to 1000 seconds to stabilize the pressure and gas flow in the chamber before activating the plasma.

[0055] The disclosed additive or additive chemical substance contains elements of Si, I, and / or C with 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 (where n = 1 to 10; x = 1 to 2; y = 1 to 3; z = 1 to 4; R, R 1 , R 2 , and R 3 are each independently selected from H, D (deuterium), a linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl group of C1 to 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.

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

Chemical formula

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

Chemical formula

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

Chemical formula

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

Chemical formula

[0060] Exemplary additives for the above formula SiI z F (4-z) may include the following

Chemical formula

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

Chemical formula

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

Chemical formula

[0063] Some of the disclosed exemplary additives containing Si element, iodine element, and / or C element are listed in Table 1. 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. The disclosed additives containing Si element, iodine element, and / or C element may also include their isomers.

[0064]

Table 1

[0065]

Table 2

[0066] More specifically, the disclosed additives have the formula SiR 1 R 2 I x F (2-x) where x = 1 to 2; R, R 1and R 2 is, independently of one another, H, D (deuterium), C1-C 10 selected from 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.

[0067] The formula SiR 1 R 2 I x F (2-x) Exemplary additives having are as follows:

Chemical formula

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

[0069] Since an etching compound preferably has high volatility, the additive chemical substance is also required to have high volatility. As described above, a small alkyl group is used as a substituent on the silicon of the additive, and thus the disclosed additive has high volatility. Another advantage brought about by using an alkyl substituent is that the possibility of carbon being incorporated into sidewall passivation due to the generation of an insufficient carbon leaving group is increased. Since the conductivity can be improved by including an aromatic group in sidewall passivation, the use of an aromatic substituent on silicon has also been proposed for new molecules. Substitution on the aromatic group is also interesting because the electronics of the aromatic ring can change the conductivity. However, one skilled in the art will understand that a low-volatility etching material can also be used. Low-volatility etching materials can be used in various ways, including heating a container or cylinder containing the low-volatility etching material and the gas line connecting to the etching tool, using a bubbler method in which an inert gas is blown through the liquid low-volatility etching material, etc., to increase the volatility by heating the source of the low-volatility etching material.

[0070] The disclosed additive is suitable for adjusting the properties of the passivation layer formed on the sidewalls of high aspect ratio holes / trenches. Sidewall passivation and downward etching occur simultaneously. The passivation layer may be derived from a carbon source in the plasma etching gas, the reaction between the etching gas and the material being exposed, or the 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 scallops. The passivation layer aids in complete etching. The disclosed additive is suitable for adjusting the properties of the highly conductive passivation layer 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 the activated 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 adding the activated additive compound. The additive to the etchant greatly affects the chemical composition of the sidewall passivation by introducing conductive elements and / or chemical bonds, thereby having a positive impact on 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, resulting in the formation of 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 charge on the sidewalls rapidly dissipates. The required bias power is below the baseline process.

[0071] The disclosed etching gas or etchant or etching compound may be a fluorocarbon and hydrofluorocarbon compound containing nitrogen, oxygen, iodine, or sulfur. Exemplary fluorocarbon / hydrofluorocarbon compounds disclosed include CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, saturated or unsaturated linear, branched, 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. Exemplary hydrogen - containing gases disclosed include H2, or halogen - containing acidic gases such as HCl, HBr, HI, or combinations thereof.

[0073] The disclosed etching compound is suitable for etching silicon - containing films including 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); metal - containing films (such as copper, cobalt, ruthenium, tungsten, indium, platinum, palladium, nickel, ruthenium, gold, etc.). The silicon - containing film may include alternating layers of SiO and SiN (ONON), 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, more preferably higher than 99.999% v / v. The disclosed fluorocarbons / hydrofluorocarbons and additives contain less than 5% by volume of trace gas impurities, and the trace gas impurities include impurity gases such as N2 and / or H2O and / or CO2 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 passing the gas or liquid through a suitable adsorbent such as 4 Å molecular sieve.

[0075] The disclosed etching compounds and additives contain any of their isomers 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 distillation of the gas or liquid to remove the isomers and can provide better process repeatability.

[0076] The disclosed etching compounds selectively etch 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 compounds do not etch the metal landing layer. The embedded landing layer may be an etch stop layer or a diffusion barrier layer. The material of the metal landing layer may be a tungsten metal word line of 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 etch stop layer such as a metal or metal oxide or nitride layer (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, etc.).

[0077] The disclosed etching compounds can be used to plasma etch a silicon-containing film on a substrate. The disclosed plasma etching method can be useful in the manufacture of semiconductor devices such as NAND or 3D NAND gates, or flash or DRAM memories or transistors such as fin-shaped field-effect transistors (FinFETs), gate-all-around (GAA) FETs, nanowire FETs, nanosheet FETs, fork sheet FETs, complementary FETs (CFETs), bulk complementary metal oxide semiconductors (bulk CMOS), MOSFETs, fully depleted silicon on insulator (FD-SOI) structures. The disclosed etching compounds can 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. Further, the disclosed etching compounds can be used to etch Si in 3D silicon through via (TSV) etching applications for interconnecting memory to logic on a substrate, and in MEMS applications.

[0078] The disclosed etching method includes providing a reaction chamber having a substrate disposed therein. The reaction chamber can be, but is not limited to, a reactive ion etching (RIE), CCP with single or multiple frequency RF sources, inductively coupled plasma (ICP), or microwave plasma reactor, or any other type of etching system capable of selectively removing a portion of a silicon-containing film or generating active species, such as any enclosure or chamber in a device in which the etching method is performed. One of ordinary skill in the art will recognize that different plasma reaction chamber designs provide different electron temperature controls. 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 trade name 2300® Flex™, or the Advanced Micro-Fabrication Equipment Inc. China (AMEC) Primo SSC HD-RIE Etcher. The RF power therein may be pulsed to control plasma characteristics and thereby further improve 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, optoelectronic, 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 a plurality of films or layers thereon from previous manufacturing steps, including a silicon-containing film or layer. The layers may or may not be patterned. Examples of suitable layers include, but are 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 (where a > 0; b, c, d, e ≥ 0), Ge, SiGe, GeSn, InGaAs, GaSb, InP; amorphous carbon, with or without dopants, antireflective 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 mask layer materials such as combinations thereof; 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 e(where a > 0; b, c, d, e ≥ 0) or an etching stop layer material such as a combination thereof; can be mentioned. Amorphous carbon (a-C) is a carbon film deposited using a PE-CVD process. The composition is mainly carbon and contains a small amount of hydrogen component. Doped a-C is an amorphous carbon film in which a dopant is additionally deposited during the deposition process. The dopant can include boron, zirconium, aluminum, titanium, and tungsten. The carbon film can also be deposited using a spin-on process, in contrast to the PE-CVD process. The silicon oxide layer can form a dielectric material such as an organic-based or silicon oxide-based low dielectric constant dielectric material (e.g., porous SiCOH film). Exemplary low dielectric constant dielectric materials are sold by Applied Materials under the trade names Black Diamond II or III. Further, a layer containing tungsten or a noble metal (e.g., platinum, palladium, rhodium, or gold) may be used. Further, an example of a silicon-containing film is Si a O b H c C d N e (where a > 0; b, c, d, e ≥ 0) can be. Throughout the specification and claims, the wafer and any related layers thereof are described as the substrate.

[0080] The disclosed etching method includes pumping the reaction chamber to 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 plasma. The inert gas is He, Ar, Xe, Kr, Ne, N 2、It can be He or a combination thereof. The etching gas and the inert gas may be mixed before being introduced into the chamber such that the inert gas constitutes from about 0.01% v / v to about 99.9% v / v of the resulting mixture. Alternatively, the inert gas can be continuously introduced into the chamber, while the etching gas is introduced into the chamber intermittently.

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

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

[0084] In another option, the vapors of the disclosed etching compounds and additives may be introduced into the chamber independently of other gases, such as when it is easier for two or more gases to react or be delivered independently.

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

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

[0087] Exemplary other 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 compound / additive and the oxidizing agent may be mixed together prior to being introduced into the reaction chamber.

[0088] Alternatively, the oxidizing agent may be introduced continuously into the chamber and the etching gas may be introduced intermittently into the chamber. The oxidizing agent may constitute from about 0.01% v / v to about 99.99% v / v of the mixture introduced into the chamber (99.99% v / v represents the introduction of a nearly pure oxidizing agent for the continuous introduction option).

[0089] Other exemplary gases in which the disclosed etching compounds and additive gases can 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, F-C≡N, CS2, SO2, H2S, SF6, trans-1,1,1,4,4,4-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, from about 1% v / v to about 25% v / v of the disclosed etching compound can be used, with the balance being C4F6 or cC4F8. As shown in the following examples, combinations of the disclosed etching compounds with conventional etching gases can result in increased etching rates while maintaining a higher selectivity between the substrate and the layer being etched in relation to the disclosed etching compound.

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

[0091] The vapors of the disclosed etching compounds and / or additives can be premixed or introduced separately into the reaction chamber. When the amount of the disclosed additive added is less (e.g., less than 20 sccm) compared to the etching gas mixed with the disclosed additive, the etching depth becomes deeper than that of the etching gas not mixed with the disclosed additive, and the selectivity of the layer to be etched to the hard mask layer (e.g., SiO2 or ONON layer to the hard mask layer) can be increased. In addition, when a small amount of the disclosed additive is mixed with the etching gas, etching without clogging is generated, and etching profile characteristics such as bowing, CD, and ellipticity are improved.

[0092] The disclosed etching compounds and / or additives can be supplied in their as-received form or in any blend with a suitable solvent such as ethylbenzene, xylene, mesitylene, decane, or dodecane. The disclosed etching compounds and additives can be present in various concentrations in the solvent. The vapor form of the disclosed etching compounds and additives can be generated by evaporating the as-received or blended solution of the disclosed etching compounds and additives through conventional evaporation steps such as direct evaporation or bubbling. The as-received or blended disclosed etching compounds and additives can be supplied in liquid form to an evaporator that evaporates it before introducing it into the reactor. Alternatively, the as-received or blended disclosed etching compounds and additives can be evaporated by passing a carrier gas through the container containing the disclosed etching compounds and additives or by bubbling the carrier gas through the disclosed etching compounds and additives. Examples of the carrier gas can include, but are not limited to, Ar, He, N2, Xe, Kr, Ne, and mixtures thereof. Thereafter, the carrier gas and the disclosed etching compounds and additives are introduced into the reactor as vapor.

[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 are in the liquid phase and can have a 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 that of the container. One skilled in the art will recognize that the temperature of the container can be adjusted in a known manner to control the amount of the disclosed etching compounds and additives to be evaporated.

[0094] The vapors of the disclosed etching compounds and additive gases and additional etching gases may be mixed before being introduced into the reaction chamber. The additional etching gases can account for about 0.01% v / v to about 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 and co-reactants are activated by a plasma to produce an activated etching gas. The etching gas is decomposed by the plasma into radical form or ions (i.e., activated etching gas). The plasma may be generated by applying RF or DC (direct current) power. The plasma can be generated by an RF source power in the range of about 25 W to about 100,000 W in a decoupled plasma etching reactor. 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 at both electrodes, without limitation. The RF frequency of the plasma can be in the range of 100 KHz to 1 GHz. Different RF sources at different frequencies may be combined and applied at the same electrode. Plasma RF pulses may be further used as bias power to control molecular fragmentation and reactions on the substrate. One 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 can be lower compared to etching without additives. In the disclosed method, by utilizing the additives, from the following examples, the bias power can be at least about 10% lower than when no additives are used.

[0097] The disclosed method of forming a sidewall passivation layer on a patterned structure of HAR includes: i) introducing a vapor of an etchant into a reactor containing a substrate; ii) forming an ion plasma from the etchant in the reactor by applying source power; iii) diffusing ions towards the substrate with or without applying bias power such that the portion of the substrate not covered by the patterned mask layer on the substrate is selectively etched away to form a patterned structure of HAR; and iv) continuing to execute the process for a predetermined time until a sidewall passivation layer is formed on the sidewalls of the patterned structure of HAR, and then turning off the source power and the bias power (if any). Here, 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 a vapor of an etchant into a reactor containing a substrate; ii) forming an ion plasma from the etchant in the reactor by applying source power; iii) diffusing ions towards the substrate with or without applying bias power such that the portion of the substrate not covered by the patterned mask layer on the substrate is selectively etched away to form a HAR patterned structure; and iv) continuing to execute 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 the low bias power (if present).

[0099] The disclosed method for forming a HAR structure during a HAR etching process on a substrate within a reaction chamber comprises: i) sequentially or simultaneously exposing the 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, wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; ii) 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 iii) allowing an etching reaction to proceed between the film not covered by the patterned mask layer and the one or more activated hydrofluorocarbon or fluorocarbon compounds or 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.

[0100] Alternatively, the disclosed method for forming a HAR patterning structure is: i) sequentially or simultaneously exposing a substrate to a vapor 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 on the film; ii) activating a plasma to generate one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and activated SiH₂I₂; and iii) allowing an etching reaction to proceed between the film not covered by the patterned mask layer and the 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 patterning structure. In some embodiments, the disclosed method further includes the substrate being simultaneously exposed to a) a vapor 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 a substrate having a highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step after or between the 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 a substrate having a highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step after or between the etching steps, where the non-etching sidewall passivation layer deposition step does not include the use of a vapor of one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and does not include the use of SiH₂I₂.In this case, even when a substrate having a highly conductive sidewall passivation layer is exposed to a non-etching sidewall passivation layer deposition step after or between etching steps, SiH2I2 and one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules do not participate in the deposition step.

[0101] Here, the substrate has a film disposed thereon and a patterned mask layer disposed on the film. The etchant includes a hydrofluorocarbon or fluorocarbon compound or a hydrogen-containing molecule and an additive compound. The etchant may include a co-reactant and / or an inert gas. After introducing the etchant into the reactor, the etchant 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 range from 1 second to 1000 seconds. The ratio of the additive compound to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule is selected such that the newly formed portion of the sidewall surface is passivated and protected from further etching. The ratio of the additive compound introduced into the reactor to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule may range from 1:200 to 1:10 in terms of flow rate (sccm) under the same conditions (e.g., the same temperature and the same pressure), preferably from 1:200 to 1:50, more preferably from 1:200 to 1:100. For example, when 0.5 sccm of SiH2I2 is used as the additive and 90 sccm of C4F8 is used as the etching gas, the ratio of SiH2I2 to C4F8 under the same conditions is 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 introduced into the reactor to the hydrofluorocarbon or fluorocarbon compound or hydrogen-containing molecule may range from 1:200 to 1:10 in terms of flow rate (mol / second) under the same conditions (e.g., the same temperature and the same pressure), preferably from 1:200 to 1:50, more preferably from 1:200 to 1:100. Thus, when 0.5 sccm of SiH2I2 is used as the additive and 30 sccm of C4F8 and 30 sccm of C4F8 and 30 sccm of CH2F2 are used as the etching gases, the ratio of SiH2I2 to C4F8 under the same conditions is 1:180 in terms of flow rate (sccm or mol / second).

[0102] The temperature of the reactor chamber can be controlled by controlling the temperature of the substrate holder or by controlling the temperature of the reactor wall. Devices used to heat the substrate are known in the art. The reactor wall is heated to a temperature sufficient to prevent condensation on the wall or in the reactor chamber, especially when a showerhead reactor is used where the substrate temperature is higher than the wall temperature. Non-limiting exemplary temperature ranges in which the reactor wall can be heated include from about -100 °C (liquid nitrogen temperature) to about 500 °C, preferably from about -100 °C (liquid nitrogen temperature) to about 200 °C, more preferably from about -100 °C to about 0 °C, even more preferably from about 20 °C to about 150 °C, and even more preferably from 20 °C to about 110 °C. The temperature of the reactor chamber 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 down 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 inside the reaction chamber is maintained at conditions suitable for the etchant or process gas. Here, the etchant or process gas includes hydrofluorocarbons or fluorocarbon etching gases or hydrogen-containing molecules, additives, co-reactants, etc. For example, the pressure inside the reactor can be maintained at about 1 mTorr to about 100 Torr, preferably about 1 mTorr to about 50 Torr, more preferably about 1 mTorr to about 10 Torr, and even more preferably about 1 mTorr to about 50 mTorr.

[0104] The etching conditions can vary during the etching process. For example, parameters such as gas flow rate, plasma power, pressure, temperature, etc. can be higher or lower at the start of the etching process compared to the end portion of the etching process near the bottom of the hole or trench. Alternatively, different etching gases may be added at different times during the etching process to improve performance, such as reducing or increasing the deposition rate of the polymer.

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

[0106] The ALD process refers to a process of generating a film by executing and repeating a series of steps. Those steps are: 1) introducing a reactive gas and ensuring the 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 a time sufficient to react with the substrate; 4) purging the reactor with an inert gas. In the CVD process, two reactive gases are added simultaneously and a 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 with respect to the mask layer, photoresist, etch stop layer, and device channel material, and cannot provide profile distortion in HAR structures such as those having an aspect ratio in the range of 1:1 to 200:1, such as DRAM and 3D NAND structures, and in contact etching applications. Alternatively, it is an aspect ratio in the range of 1:1 to 20:1, and an aspect ratio in the range of 21:1 to 200:1. The disclosed etching method is suitable for etching HAR patterned structures having an aspect ratio of 1:1 to 200:1. Alternatively, the disclosed etching method is suitable for etching HAR patterned structures having an aspect ratio of about 1:1 to about 20:1, an aspect ratio between about 21:1 and about 200:1, an aspect ratio of about 1:1 to about 60:1, or an aspect ratio of about 61:1 to about 200:1. The disclosed etching method improves etching profile characteristics such as bowing, CD, and ellipticity, reduces sidewall etching, and reduces the formation of bowing and scallops.

Example

[0108] The following non-limiting examples are provided to further illustrate embodiments of the present invention. However, the examples are not intended to be comprehensive and are not intended to limit the scope of the present invention described herein.

[0109] In the following examples, experiments were conducted using a commercially available LAM tool 4520XLe 200 mm (CCP dual-frequency plasma) or a commercially available AMEC 300 mm Primo SSC HD-RIE etcher. To prove reproducibility, each etching test was repeated at least 3 times. The standard deviation of the average of the three measurements is shown as error bars in the charts. Subsequently, the composition of the polymer was examined by X-ray photoelectron spectroscopy (XPS).

[0110] Example 1: Measurement of the Electrical Conductivity of the Polymer Figures 1 to 3 show the conductivities of C4H2F6 with or without the additives CH3I, C4F9I, or SiH2I2 measured on a flat wafer. The current (I)-voltage (V) was measured using a mercury probe. A drop of deionized water was added to the back surface of the wafer to improve the contact resistance. This can help reduce the 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 decreases the breakdown voltage. The conductivity of C4H2F6 with additives increases compared to that of C4H2F6 without additives. Refer to the current differences in Figures 1 to 3. As shown in Table 1, 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%.

[0111] [Table 3]

[0112] Example 2: ONON Hole Pattern Etching Using CH3I as an Additive CH3I was added to an etching recipe containing C4H2F6 for ONON (i.e., alternating layers of SiO / SiN) hole pattern etching on a patterned wafer or substrate due to promising performance on a flat thin film (higher selectivity to an a-C mask and increased polymer conductivity). The patterned wafer has an ONON layer with an amorphous carbon (a-C) mask layer hole-patterned thereon. The etching recipe may also include O2.

[0113] Four conditions, 30 / 10 sccm, 35 / 5 sccm, 40 / 5 sccm, and 40 / 10 sccm C4H2F6 / CH3I flow rates were tested for preliminary screening. 30 / 10 sccm and 35 / 5 sccm have the same total gas flow rate. Since CH3I is highly polymerizable, etch stop was observed in SEM images when the CH3I flow rate was 10 sccm or more. Although an improvement in etching selectivity was shown under the 40 / 5 sccm condition, further adjustment of the etching recipe is required. The SEM conditions are as follows: Accel. voltage: 5.0 kV; emission current: 20 μA; magnification: ×30.0 k.

[0114] CH3I has a very high polymerizability and may clog the patterned mask layer. When the flow rate added to the ONON etching composition is 10 sccm or more, it may further cause an etch stop. When CH3I is added to the etching recipe, the process window of the O2 flow rate shifts from 68 sccm to 74 - 76 sccm. For the optimized CH3I recipe: ONON etching rate (ER): 510 nm / min (without CH3I, the measured ONON ER is 516 nm / min); ONON vs. a-C selectivity: 11.2 - 12 (without CH3I, the ONON vs. a-C selectivity is 11.4 - 12). Figures 4 - 9 are comparisons of ER, selectivity, sidewall bowing, ellipticity, and CD due to the difference in bias power of C4H2F6 with or without the additive CH3I. Overall, the recipe with CH3I shows a lower 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 7000 W, adding CH3I to the recipe does not show a significant change in the ellipticity of the a-C mask hole, and the measured ellipticity is 93% for the recipe without CH3I and 94% for the recipe with CH3I. At a bias power of 5600 W, for the recipe without CH3I, the a-C mask profile deteriorates with the decrease in bias power, while for the recipe with CH3I, little effect is observed. At a bias power of 4200 W, for the recipe with CH3I, improvements in etching performance such as etching rate (ER), selectivity, ellipticity of the a-C mask, and tilt angle are shown. The etching performance is summarized in Table 2.

[0116]

Table 4

[0117] In summary, when using the additive CH3I, the etch front of the HAR feature and the surface passivation (also known as the polymer layer) on the sidewalls are improved, and the passivation changes according to the fluctuations in plasma etching conditions (RF power, process time, etc.). Furthermore, when adding CH3I as an additive to a hydrofluorocarbon etching gas (such as C4H2F6), the bias power can be reduced by 40% without degrading the etching performance such as the etching rate, selectivity, ellipticity, profile CD, etc.

[0118] Example 3: Chemical Composition of Polymer and Electrical Conductivity of Polymer Substrate: To obtain the I-V characteristics of only the polymer, a low-resistivity Si substrate (less than 0.02 Ω·cm) was used for polymer deposition instead of the SiO2 substrate. The Si substrate was cut into 1-inch × 1-inch coupons to facilitate I-V measurements using a mercury probe.

[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 with an ellipsometer.

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

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

[0122] Table 3 shows the bond concentration ratios of C-C vs. C-F x / C-I (where x is an integer). The bond concentration ratios of C-C:C-F x / C-I are C4F9I < C4F8 + C4F9I < C4F8 < C4H2F6 + C4F9I < C4H2F6 from the lower to the higher. The C-C bond is a non-polar 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 interrelated. Generally, adding iodine to the polymer increases its conductivity, and as a result, as shown in Example 2, the bias power can be at least about 10% lower compared to the case without using an additive without degrading the etching performance such as etching rate, selectivity, ellipticity, profile CD, etc.

[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 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 for comparison 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. The various etching parameters in the etching process are listed in Table 4. Here, DC represents the duty cycle, and the RF power represented as "700 / 200" means that the RF power cycles between 700 W and 200 W at a frequency (Fr) of 500 Hz as described. The ratio of SiH2I2 to C4F6 is 1:64 in terms of flow rate (sccm and / or mol / second).

[0127]

Table 6

[0128] The etching results of the C4F6 baseline vs. the process using SiH2I2 are shown in Table 5. When the SiH2I2 etching gas was used as an additive gas, the etching rate of SiO2 increased by 5%. The etching rate of the a-C mask layer decreased (-33%) with the introduction of the SiH2I2 etching gas, resulting in a 57.4% improvement in the SiO2:a-C selectivity. More bowing was observed when using SiH2I2, which is thought to be mainly due to the improved preservation of the a-C mask layer. Furthermore, when the SiH2I2 etching gas was used as an additive gas, the etching depth increased by 5.3%, while the etching of the mask layer was less (44.8%) than when not using the SiH2I2 additive gas.

[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 is 1:64 in terms of flow rate (sccm and / or mol / sec). The etching results of the 5600W process bias power using the 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 for both the C4F6 baseline and the 5600W process bias power using SiH2I2. In the etching process using SiH2I2, it is shown that the ER of SiO2 increased (+6.6%), the ER of the a-C mask decreased (-12%), and the selectivity of SiO2 vs. a-C was improved by approximately 22.2%. Boiling was observed in both processes, but boiling was slightly improved by adding SiH2I2. Furthermore, when the SiH2I2 etching gas was used as an additive gas, the etching depth increased by 6.6% while the etching of the mask layer was less (8.1%) than when no SiH2I2 additive was used.

[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 is 1:64 in terms of flow rate (sccm and / or mol / sec). The etching results of the 4200W process bias power using the 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 decreases significantly (by more than 20%) regardless of the presence or absence of SiH2I2. The ER of SiO2 increases (+4.8%) compared to the baseline, and the ER of the a-C mask decreases, resulting in an improvement in the selectivity of SiO2:a-C of approximately 11.5%. Similar profiles such as maximum CD, bottom CD, and bowing were observed in the etching process regardless of the presence or absence of SiH2I2. Furthermore, when the SiH2I2 etching gas was used as an additive gas, the etching depth increased by 4.5% while the etching of the mask layer was less (4.9%) than when no SiH2I2 additive was used.

[0133]

Table 9

[0134] Example 7: Polymer Property Evaluation Using SiH2I2 The polymer was deposited on a flat a-C 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, a source power of 700 W / 200 W, a duty cycle of 70%, and gas flows of 25 sccm of C4F8, 0.5 sccm of SiH2I2, and 150 sccm of Ar. The ratio of SiH2I2 to C4F6 is 1:50 in terms of flow rate (sccm and / or mol / sec). XPS analysis of the polymer showed a composition of 64% carbon, 26% fluorine, 8% oxygen, 2% silicon, and 0.3% iodine. This indicates that when SiH2I2 is mixed with a fluorocarbon gas on the a-C mask surface, a polymer containing silicon and iodine is deposited.

[0135] Example 8: Evaluation of Polymer Properties 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, a source power of 700 W / 200 W, a duty cycle of 70%, and gas flows of 25 sccm of C4F8, 0.5 sccm of SiH2I2, and 150 sccm of Ar. The ratio of SiH2I2 to C4F8 is 1:50 in terms of flow rate (sccm and / or mol / sec). High-resolution XPS analysis of the polymer showed that the polymer contains carbon, fluorine, silicon, iodine, and oxygen. For silicon, the main bond formations were Si-C bonds and a small amount of Si-F bonds. Iodine was detected as I-C-O bonds. This indicates that when SiH2I2 is mixed with a fluorocarbon gas on the SiO2 surface, a polymer containing silicon and iodine is deposited.

[0136] Example 9: Measurement of the Electrical Conductivity of the Polymer. With a bias of 1000 W / 200 W, a source of 950 W / 200 W, a duty cycle of 70%, 4 sccm of C4F8, 4 sccm of C4F6, 5 sccm of CH2F2, 15 sccm of O2, 150 sccm of Ar, with or without 0.5 sccm of SiH2I2, this polymer was deposited using a 300 mm plasma etcher. The ratio of SiH2I2 to the total of C4F8, C4F6, and CH2F2 is 1:26 in terms of flow rate (sccm and / or moles / second). The conductivity was measured by the method described in Example 1. It was found that the conductivity of the polymer without SiH2I2 is about 1E-10 (A) at 100 V, and the conductivity of the polymer containing SiH2I2 is about 6E-10 (A) at 100 V. This indicates that the 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 a-C mask decreases with the addition of SiH2I2, and the selectivity of SiO2 to a-C is improved by about 57.4%. At a bias power of 5400 W, the oxide etching rate decreases in both recipes. When SiH2I2 is added, the ER of SiO2 increases (+6.6%), the ER of the a-C mask decreases, and the selectivity of SiO2 to a-C is improved by about 22.2%.

[0138] The oxide etching rate decreases at low plasma bias powers such as 5400 W and 4200 W bias power. In the process using SiH2I2, it has been shown that the etching rate of oxide holes increases and the selectivity to the a-C mask is improved. When SiH2I2 is added, oxide holes can be etched in a method with a bias power lower (e.g., 5400 W) but equivalent to the baseline. Bowing was observed under both conditions. The polymer deposited on the a-C mask and SiO2 flat film using a fluorocarbon such as C4F8 and the additive SiH2I2 is composed of carbon, fluorine, oxygen, silicon, and iodine, and Si-C bonds, Si-F bonds, and I-C-O bonds are formed in 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 total of C4F8, C4F6, and CH2F2 is 1:180 in terms of flow rate (sccm and / or mol / sec). The SiO2 or ONON hole pattern may be a 3-μm-thick PETEOS (PECVD TEOS) SiO2 layer or an alternating SiO / SiN layer deposited on a Si substrate. Similar to the pattern used in Example 4, an a-C mask layer was deposited on the SiO layer or the alternating SiO / SiN layer. 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 hole was approximately 164 nm. O2 and Ar are appropriately added, such as 40 sccm of O2, 150 sccm of Ar, etc. The plasma conditions are the same as the plasma conditions described in Table 4. When using the SiH2I2 etching gas as an additive gas, the etching rate and etching depth of SiO2 or ONON increase, the selectivity of SiO2 vs. a-C or ONON:a-C is improved, a conductive passivation layer is formed, and an etching profile with little or no bowing and clogging is formed.

[0140] Many additional changes in the details, materials, steps, and arrangements of the parts described and illustrated herein in order to explain the nature of the present invention can be made by those skilled in the art within the principles and scope of the present invention as set forth in the appended claims. Accordingly, the present invention is not intended to be limited to the embodiments shown and / or the specific embodiments in the accompanying drawings above.

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

Claims

**Claim 1** A method for forming a high aspect ratio (HAR) structure during a high aspect ratio (HAR) etching process on a substrate within a reaction chamber, comprising: 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 on the film; activating a plasma to generate activated one or more hydrofluorocarbons or fluorocarbon compounds or activated one or more hydrogen-containing molecules and an activated additive compound; and advancing 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 comprising the steps of: **Claim 2** The method according to claim 1, further comprising the step of introducing an oxidizing agent into the reaction chamber, wherein the oxidizing agent is selected from O ２ , O ３ , CO, CO ２ , NO, N ２ O, NO ２ , H ２ O, H ２ O ２ , COS, SO ２ , and combinations thereof. **Claim 3** The method further includes a step of introducing an inert gas into the reaction chamber, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N ２ The method according to claim 1, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N **Claim 4** The method of claim 1, wherein a highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structure. **Claim 5** The conductivity of the highly conductive sidewall passivation layer formed using the activated one or more hydrofluorocarbons or fluorocarbon compounds or the activated one or more hydrogen-containing molecules 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 one or more hydrofluorocarbons or fluorocarbon compounds or the activated one or more hydrogen-containing molecules without adding the activated additive compound. The method according to claim 4. **Claim 6** The above-mentioned one or more hydrofluorocarbons or fluorocarbon compounds 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 saturated or unsaturated linear, branched, cyclic hydrofluorocarbons, or combinations thereof, fluorocarbons and hydrofluorocarbon compounds containing nitrogen, oxygen, iodine, or sulfur, and the above-mentioned one or more hydrogen-containing molecules are H ２ or a halogen-containing acidic gas containing HCl, HBr, HI or a combination thereof. The method according to claim 1. **Claim 7** The method of 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 by flow rate (moles / second) at the same temperature and the same pressure. **Claim 8** 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 1:50 in terms of flow rate (mol / sec) under the same temperature and the same pressure.

9. 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 1:100 in terms of flow rate (mol / sec) under the same temperature and the same pressure.

10. The method according to claim 1, wherein the flow rate of the additive compound is 0.5 sccm.

11. The method according to claim 1, wherein the etching temperature is in the range of about -100°C to about 200°C.

12. The method according to claim 1, wherein the etching temperature is in the range of about -100°C to about 0°C.

13. The additive compound contains silicon element and iodine element and has the following formula: SiR １ R ２ I ｘ F （２－ｘ） (wherein 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) The method according to any one of claims 1 to 12.

14. wherein the additive compound is SiH ２ I ２ The method according to any one of claims 1 to 12.

15. The additive compound is a silicon-containing compound selected from the following 【Chemical 1】 The method according to any one of claims 1 to 12.

16. The method according to any one of claims 1 to 12, wherein the film is a silicon-containing film containing O and / or N and optionally containing dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

17. A method of forming a HAR patterned structure, A step of sequentially or simultaneously exposing a substrate to a vapor of one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and SiH ２ I ２ wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; Activating a plasma to generate one or more activated fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules and activated SiH ２ I ２ and; and A film not covered by the patterned mask layer, the activated one or more fluorocarbon or hydrofluorocarbon compounds or the activated one or more hydrogen-containing molecules and the activated SiH ２ I ２ to cause an etching reaction to proceed between them to selectively etch the film from the patterned mask layer, thereby forming the HAR patterned structure; comprising a method.

18. Further comprising the step of 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 , and combinations thereof, the method according to claim 17.

19. The method further includes a step of introducing an inert gas into the reaction chamber, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N ２ The method according to claim 17, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, and N

20. The method according to claim 17, wherein a highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structure.

21. The conductivity of the highly conductive sidewall passivation layer formed using the activated one or more fluorocarbon or hydrofluorocarbon compounds or the activated one or more hydrogen-containing molecules and the activated SiH ２ I ２ is at least about 10% higher than the conductivity of the highly conductive sidewall passivation layer formed using the activated one or more fluorocarbon or hydrofluorocarbon compounds or the activated one or more hydrogen-containing molecules without adding the activated SiH ２ I ２ The method according to any one of claims 17 to 20.

22. The method according to claim 20, wherein the substrate is simultaneously exposed to a) the vapor of the one or more fluorocarbon or hydrofluorocarbon compounds or the one or more hydrogen-containing molecules, and b) SiH ２ I ２ and.

23. The method according to claim 22, which does not include exposing the substrate having the highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step after or between the etching steps.

24. After the etching step or between etching steps, exposing the substrate having the highly conductive sidewall passivation layer to a non-etching sidewall passivation layer deposition step that does not include using a vapor of the one or more fluorocarbon or hydrofluorocarbon compounds or one or more hydrogen-containing molecules, and does not include the use of SiH ２ I ２ The method of claim 22, which does not include the use of.

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