Dielectric plasma etch using C2H2F2

Abstract

An etching method for forming a structure by selectively etching one or more dielectric films deposited on top of the one or more dielectric films in a substrate using a patterned mask layer includes: mounting the substrate in a reaction chamber; an etching gas containing C2H2F2 is introduced into the reaction chamber; converting the etching gas into a plasma; and allowing an etch reaction between the plasma and the one or more dielectric films such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure.

Description

[0001] Cross-referencing related applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 239,041, filed August 28, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a method for manufacturing semiconductor chips by using hydrofluorocarbon etching gas C2H2F2 plasma to etch dielectric materials, such as back-end process (BEOL) interconnects (trench etching and via etching) for logic devices. Background Technology

[0004] Traditional plasma etching gases used in semiconductor device manufacturing are typically fluorocarbons or hydrofluorocarbons used for etching silicon-containing materials such as SiO2, SiN, and SiOCH. However, the fluorocarbons and hydrofluorocarbons used often have high global warming potential (GWP). Table 1 lists the GWPs of commonly used etching gases in the semiconductor industry, along with other molecules that may be plasma byproducts and other chemicals. Traditional etching gases used for etching back-to-the-line (BEOL) dielectric materials such as low-k films are CF4 or CHF3, while other fluorocarbon gases, including C4F8 or CH2F2, can be used for SiO dielectric etching. As can be seen from the table, CF4 (6630) and CHF3 (12400) have extremely high GWPs. Therefore, these molecules are detrimental to global warming. Other commonly used fluorocarbons or hydrofluorocarbons can include CH2F2, CH3F, C4F8, C4F6, C2F6, C3F8, etc. Furthermore, byproducts from etching can include NO2, CO, CO2, COF4, SiF4, etc.

[0005] Table 1

[0006] However, the principle of plasma etching is that molecules break down due to the energy and collisions of the plasma, resulting in bond breakage, the generation of byproducts, etching of the substrate, the production of reaction byproducts, and the recombination of fragments to form new materials. Therefore, plasma breakup and chemical composition are extremely complex and difficult to predict. Thus, although the molecules entering the plasma may themselves have a high GWP, the GWP of the emissions leaving the plasma etching equipment depends on the breakup of the molecules and the resulting recombination and byproducts. As the gases leave the plasma etching tool, they flow through a vacuum pump, are diluted with nitrogen, and typically pass through a scrubbing device. Scrubbers are generally of two types. The first is a plasma device that further breaks down the molecules. The second is a burner that typically burns the emissions by adding something like methane. Both types of scrubbers break down etching byproducts. Plasma devices use energy from the RF, while burners use thermal energy. Further elimination can be performed using wet or dry scrubbers to remove substances like HF or other toxic materials. The challenge is that CF bonds are very strong and difficult to break. Therefore, while it is important to use etching gases with low GWP, it is also important to ensure that the emissions also have a low GWP. This is especially true for lower plasma power processes such as BEOL dielectric etching, where the lower source power of the etching tool may not completely decompose the incoming molecules. Therefore, if the incoming etch molecules are high GWP, a high proportion of undissociated gas will leave the chamber, resulting in high GWP emissions or high CO2 equivalent emissions.

[0007] SiO and SiOCH materials are used as insulating films in the fabrication of semiconductor chips. Various compositions of SiO and SiOCH films are used (typically containing other elements such as N, H, and B). The etching properties of SiOCH films are generally similar to those of SiO films using fluorocarbon etching gases. The masks used in the patterning process can also vary. For example, films such as TiN, carbon (amorphous carbon or spin-coated carbon), and SiN are commonly used as mask materials when etching SiO and SiOCH films. The selectivity of etching SiO / SiOCH relative to the mask material is crucial. Fluorocarbon polymers are used during etching to protect the surface and sidewalls of the patterned structure to control selectivity. Etching agents such as O2, N2, or Ar are used to control polymer formation, which can chemically or physically remove the polymer in various ways. The polymer is formed by breaking down etched molecules in plasma to form various free radical structures, which recombine on the surface to form the polymer material. Etching of silicon materials primarily originates from F-matter to form volatile SiF4. Polymers play a crucial role in protecting surfaces from ion bombardment and chemical erosion by plasma, while also providing F The chemical structure of Si is crucial for the formation of different materials in the plasma that drives the formation of polymers and etched materials, and will also affect the gas phosphating power (GWP) of emissions from the plasma etching machine.

[0008] Therefore, chemical structure is crucial for etching performance and the impact of global warming (both the molecular GWP and the GWP from process emissions). The etching performance and emissions of fluorocarbon molecules are difficult to predict.

[0009] US20160118266 discloses a method for manufacturing a semiconductor device, the method comprising forming a first etch layer and a second etch layer stacked on a substrate, and forming a recessed region by etching the first and second etch layers under plasma. The etching gas comprises a compound represented by formula I or II. This compound includes at least one of 1,1,1,2,3,3-hexafluoropropane, 2,2,2-trifluoroethane-1-thiol, 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3-pentafluoropropane, and 1,1,2,2-tetrafluoro-1-iodoethane, 2,3,3,3-tetrafluoropropylene, and 1,1-difluoroethylene (which does indeed include C2H2F2 used in the plasma etching process).

[0010] US2020234962 discloses a dry etching gas composition containing saturated or unsaturated hydrofluorocarbon compounds (excluding 1,2,2,3-pentafluorocyclobutane and 1,1,2,2-tetrafluorocyclobutane) represented by the following general formula (1): C x H y F z , where x, y, and z are integers satisfying 2 ≤ x ≤ 4, y + z ≤ 2x + 2, and 0.5 < z / y < 2. Among many different molecules, C2H2F2 is listed as an example along with the oxidizing agent used in the scheme.

[0011] KR970023632 discloses a method for forming polymer patterns according to polymer deposition, wherein one of the reactive gases (C4F8, CHF3, CF4, C2F4, C2F6, C2F6) used to form carbon polymers using gases containing HBr, CCl4, C2H2F2, and C2HF5 is BCl3 gas, characterized by the method for forming patterns according to polymer deposition. KR970023632 also discloses C2H2F2 among other gases, which includes CHF3 (known as a poor etchant with high GWP). The document also includes the addition of other gases such as BCl3 or HBr.

[0012] US5814563 discloses a method for etching dielectrics and other films such as TiN. The composition contains C₂H₂F₂, an etchant such as CF₄, an nitrogen-containing gas such as NH₃, and an oxidizing agent such as CO, and / or Ar for sputtering. The NH₃-generating gas is a gas capable of producing NH₃-containing substances, such as those containing NH₂. - NH3 or NH4 + Gases containing ions or molecules, including, for example, NH3, NH4OH, CH3NH2, C2H5NH2, C3H8NH2, and mixtures thereof. Among these gases, NH3 is preferred.

[0013] KR19980085478 A discloses an etching method for forming contact holes using reactive ion etching (RIE) with the following conditions: CF4 100-2000 sccm, CHF3 100-2000 sccm, C2H2F2 100-2000 sccm, RF (radio frequency) power 200-3000 W, pressure 100-2000 mT, and cathode temperature -40°C to 40°C.

[0014] US2007184605 discloses a method for manufacturing a flash memory device. A dry etching process is used under conditions of excess polymer to perform an etching process for controlling the effective field height of the insulating layer, thereby forming a first spacer on the sidewalls of the floating gate pattern. Examples of mask materials are transition metals, preferably Ni. Etching compositions of C2H2F2, C4F6 or C4F8 or C5F8, Ar, and O2 are disclosed, but N2 is not mentioned.

[0015] US2009114944 discloses processing a substrate to form an LED device, including etching with a mask, wherein the etchant comprises gases from a list including C2H2F2 and oxygen-containing gases. N2 is not mentioned. The list of gases includes CF4, CHF3, C2H2F2, or C2F3Cl3.

[0016] US2009155731 discloses a method for mitigating pattern defects such as critical size (CD) deviations and line edge roughness (LER) during a pattern transfer process. The method includes forming one or more layers on a substrate, forming a radiation-sensitive mask layer on the one or more layers, and forming a pattern in the radiation-sensitive mask layer using a photolithography process. Once the pattern is formed, the edges of the pattern are smoothed by exposing the pattern in the radiation-sensitive mask layer to a plasma containing hydrofluorocarbons. For example, the process gas may include CHF3, CH2F2, C2HF5, C2H2F2, or C2H4F2, or any combination of two or more thereof, as initial components. Furthermore, the process gas may further include a fluorocarbon gas, or a hydrocarbon gas, or both, as an initial component. Additionally, the process gas may further include an inert gas, such as a rare gas, as an initial component. Furthermore, the process gas may further include O2, CO, CO2, NO, NO2, N2O, H2, N2, or NH3, or any combination of two or more thereof, as initial components.

[0017] US2011272813 discloses a method for manufacturing a semiconductor device comprising: forming a capping insulating film on a substrate, comprising Si and C; forming an organic silicon dioxide film on the capping insulating film having a higher carbon-to-silicon atomic ratio than that of the capping insulating film; and forming two or more recesses with different opening diameters in the organic silicon dioxide film by plasma processing using a mixture of an inert gas, a nitrogen-containing gas, a fluorinated hydrocarbon gas, and an oxidizing gas. The use of a mixture of an inert gas, a nitrogen-containing gas, a fluorinated hydrocarbon gas, and an oxidizing gas is described. The fluorinated hydrocarbon gas includes gases such as C2H2F2 and CHF3. The nitrogen-containing gas includes at least one selected from the group consisting of nitrogen, ammonia, and amines. The purpose is to etch a low-k type silicon-containing film. The oxidizing gas can be O2, CO2, CH3OH, C2H5OH, C3H7OH, N2O, NO, N2O3, NO2, N2O4, and N2O5. The hard mask material is SiO2. The cover insulating film is a film made of either silicon carbide (SiC) or silicon carbonitride (SiCN), or a laminate thereof. Alternatively, the cover insulating film is a film made of oxygen-containing silicon carbide (SiCON) (which contains unsaturated hydrocarbons, amorphous carbon, and oxygen), or a laminate of SiCN, SiC, and oxygen-containing silicon carbide films.

[0018] US2009111275 discloses a plasma etching method that prevents residue from adhering to the bottom and sides of vias and trenches. (This will be handled by C...) w F x(x and w are predetermined natural numbers) The interlayer insulating film formed and the metal layer or metal-containing layer formed on the substrate are simultaneously exposed to plasma generated by the process gas. The process gas includes C y F z (y and z are predetermined natural numbers) A mixture of gas and N2 gas, wherein the flow rate of N2 gas in the process gas is higher than that of C. y F z Gas flow rate. The process gas is C. y F z (Non-hydrogen-containing gas), but in some cases, H-containing gases are mentioned. For example, CF4 is used as a fluorinated hydrocarbon-based gas in process gases (C... y F z (y and z are predetermined natural numbers) gas), the process gas containing fluorinated hydrocarbon-based gases is not limited to this, but can be C4F8, C2F6, C3F8, C4F6, or C5F8. If CHF3 is used as the hydrogen-containing gas or NF3 or SF6 is used as the non-carbon-containing gas, the same effects as those of the present invention can be expected.

[0019] US2005186801 discloses a method for fabricating a semiconductor integrated circuit device with a damascene interconnect structure by embedding a conductive film into a recess (such as a trench or a hole) formed in an organic insulating film. The organic insulating film constitutes an interlayer dielectric film and contains an organosiloxane as a major component. The recess (such as a trench or a hole) is formed by subjecting the organic insulating film to plasma dry etching in a CF-based gas / N2 / Ar gas to suppress the formation of anomalous shapes at the bottom of the recess during the formation of a photoresist film on the organic insulating film, and subsequently forming the recess therein with the photoresist film serving as an etching mask. Not only C4F8 can be used, but also gases such as CHF3, CF4, CH2F2, or C5F8 can be used. Furthermore, saturated cyclic fluorocarbons (such as C3F6), unsaturated cyclic fluorocarbons (such as C5F9), acyclic fluorocarbons (such as CF4, CHF3, or CH2F2), or fluorocarbon iodides (such as CF3I), developed as countermeasures against fleon, can be used as CF gases. Instead of CF gases, SF6 can be used, for example. The dielectric can be an organic spin-coated glass material. One example given is the use of a C4F8 / N2 / Ar etching scheme. Figure 9The diagram shows that increasing the N2 flow rate increases the etch rate of the organic SOG and the etch selectivity relative to SiN (maximum at an N2 flow rate of 200 sccm (Ar flow rate of 420 sccm, so the ratio is about 0.5)) and decreases at higher N2 flow rates. Available etch selectivity and etch rate are also described as achievable at nitrogen flow rates ranging from 150 sccm (C / N ratio: 0.16) to 300 sccm (C / N ratio: 0.08), which can be broadened to a range of 50 sccm (C / N ratio: 0.48) to 500 sccm (C / N ratio: 0.48).

[0020] US2014363975 discloses a cyclic etching process in which the deposition gas is selected from C4F8, C2F4, C2H2F2 and CCl4, and the etching gas is selected from CF4 and SF6. Chlorine-based etching gases include Cl2, BCl3, SiCl4 and SiCl2H2, and bromine-based etching gases include Br2 and HBr.

[0021] Conventional fluorocarbons and hydrofluorocarbons can have high global warming potential (GWP), and when exposed to high-power plasma, they decompose and may form substances that also have high GWP. These high-GWP substances are emitted. In some cases, these high-GWP substances can pass through scrubbing devices, but these high-GWP substances have varying efficiencies. Therefore, there is a need for both lower-GWP etching gases that function in etching dielectric materials and gases that decompose in plasma and produce lower-GWP byproducts (compared to conventional fluorocarbons and hydrofluorocarbons used in the semiconductor industry).

[0022] Therefore, it is necessary to have both etching gases with lower GWP than commonly used hydrofluorocarbon and fluorocarbon etching gases (such as CF4) that function in the etching process, and gases that decompose in plasma and produce byproducts with lower GWP than commonly used hydrofluorocarbon and fluorocarbon etching gases. Summary of the Invention

[0023] An etching method is disclosed for forming a structure by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; and An etching reaction is permitted between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure. The disclosed etching method may include one or more of the following features: Further includes: One or more hydrofluorocarbon or fluorocarbon etching gases are added to C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F... 10 C5F8, or C6F6, C7F 14 C7F 16 or C8F 16 The one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbons. x F y H z A molecule, where x, y, and z are integers, 1 ≤ x ≤ 8, selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F 10 C5HF7, or combinations thereof; Further, it includes adding an additive to C2H2F2, wherein the additive is selected from H2, SF6, NF3, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, or HF; Further, this includes adding the co-reactant to C2H2F2; The co-reactant is an inert gas selected from the following: Ar, Kr, Xe, Ne, N2, He or a combination thereof; The co-reactants are selected from N2, Ar, or a combination of both, with each having an arbitrary ratio ranging from 0% to 100%. The co-reactant is selected from N2, Ar, or a combination of both; The combination of N2 and Ar has a ratio ranging from 0% to 100%; Further includes: Add co-reactant N2 to C2H2F2; Further, it includes adding the co-reactant Ar to C2H2F2; C2H2F2 is an isomer of C2H2F2 with CAS number: 75-38-7; C2H2F2 is an isomer of C2H2F2 with CAS number: 1630-78-0; C2H2F2 is an isomer of C2H2F2 with CAS number: 1630-77-9; C2H2F2 is an isomer of C2H2F2 with CAS number: 1691-13-0; The substrate has a temperature range of -20°C to 300°C; The substrate has a temperature range of -20°C to -196°C; The pressure in the chamber is between approximately 0.1 mTorr and approximately 1000 mTorr; The pressure in the chamber is between approximately 1 millitor and approximately 10 tors; The pressure in the chamber is between approximately 10 millitors and approximately 1 tor; The pressure in this chamber ranges from 1 millitor to several hundred millitors; The pressure in the chamber is maintained between 15 and 30 millitors; The one or more dielectric films are SiO2 and SiOCH films; The CO2 equivalent emissions from this reaction chamber are at least 10% lower than the CO2 equivalent emissions when using CF4 as the etching gas; and The CO2 equivalent emissions from this reaction chamber are at least 10% lower than the CO2 equivalent emissions when using CF4 as the etching gas.

[0024] An etching method is disclosed for forming a structure with low CO2 equivalent emissions by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; and This allows an etching reaction to occur between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure. The CO2 equivalent emissions from this reaction chamber are at least 10% lower than those using CF4 as the etching gas. The disclosed etching method may include one or more of the following characteristics: Further includes: One or more hydrofluorocarbon or fluorocarbon etching gases are added to the etching gas C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F6, C4F6, C2F4, C3F6, C4F6, C4F6, C2F4, C3F6, C4F6, C2 ... 10 C5F8, C6F6, C7F 14 C7F 16 or C8F 16 The one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbons. x F y H z A molecule, where x, y, and z are integers, 1 ≤ x ≤ 8, selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F 10 C5HF7, or combinations thereof; Further, it includes adding an additive to C2H2F2, wherein the additive is selected from H2, SF6, NF3, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, or HF; Further, this includes adding the co-reactant to C2H2F2; The co-reactant is an inert gas selected from the following: Ar, Kr, Xe, Ne, N2, He or a combination thereof; The co-reactants are selected from N2, Ar, or a combination of both, with each having an arbitrary ratio ranging from 0% to 100%. The co-reactant is selected from N2, Ar, or a combination of both; The combination of N2 and Ar has a ratio ranging from 0% to 100%; The method further includes adding co-reactant N2 to C2H2F2; Further, it includes adding the co-reactant Ar to C2H2F2; C2H2F2 is an isomer of C2H2F2 with CAS number: 75-38-7; C2H2F2 is an isomer of C2H2F2 with CAS number: 1630-78-0; C2H2F2 is an isomer of C2H2F2 with CAS number: 1630-77-9; C2H2F2 is an isomer of C2H2F2 with CAS number 1691-13-0; and The substrate has a temperature range of -20°C to 300°C.

[0025] An etching method is disclosed for forming a structure by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching composition containing a gas mixture of C2H2F2 and an inert gas is introduced into the reaction chamber; The etching composition is transformed into plasma; and This allows an etching reaction to occur between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure. The substrate has a temperature range of -20°C to 300°C. The disclosed etching method may include one or more of the following characteristics: The inert gas is selected from Ar, Kr, Xe, Ne, N2, He, or a combination thereof; The inert gas is selected from N2, Ar, or a combination of both in any ratio ranging from 0% to 100%. The inert gas is selected from N2, Ar, or a combination of both; The combination of N2 and Ar has a ratio ranging from 0% to 100%; The inert gas is N2; The inert gas is Ar; and C2H2F2 is an isomer of C2H2F2 with CAS number 75-38-7.

[0026] Symbols and nomenclature

[0027] The following detailed description and claims utilize many abbreviations, symbols, and terms commonly known in the art, and include: As used in this article, the indefinite article “a / an” means one or more.

[0028] As used herein, “about” or “around / approximately” in the text or claims means ± 10% of the value.

[0029] As used herein, “room temperature” in the text or claims means approximately 20°C to approximately 25°C.

[0030] The term "substrate" refers to one or more materials on which processes are performed. A substrate can refer to a wafer having one or more materials on which processes are performed. A substrate can be any suitable wafer used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. A substrate can also have one or more different material layers deposited thereon from previous manufacturing steps. For example, a wafer can include silicon layers (including but not limited to crystalline, amorphous, porous, etc.), silicon-containing layers (including but not limited to SiO2, SiN, SiON, SiCOH, etc.), metal or metal-containing layers (including but not limited to copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.), or combinations thereof. Furthermore, a substrate can be planar or patterned. A substrate can be an organically patterned carbon iodide film. The substrate may include an oxide layer of dielectric material (e.g., ZrO2-based, HfO2-based, TiO2-based, rare earth oxide-based, ternary oxide-based, etc.) used as a dielectric material in field-effect transistors (FETs) such as FinFET, MOFSET, GAAFET (Gate All-Around FET), strip FET, nanosheet, fork FET, complementary FET (CFET), MEMS, 3D NAND, MIM, DRAM, or FeRam device applications, or a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode. The substrate may include alternating layers of oxides (e.g., SiO) and nitrides (e.g., SiN). Those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a material of a certain thickness laid or spread on a surface, and that surface may be trenches or lines. Throughout the specification and claims, the wafer and any associated layers thereon are referred to as the substrate. The substrate can be any solid having functional groups on its surface that tend to react with reactive heads that assemble a self-assessed monolayer (SAM), and can include, but is not limited to, 3D objects or powders.

[0031] The term “wafer” or “patterned wafer” refers to a wafer having a stack of films on a substrate, at least the topmost film of the stack having morphological features or patterns that have been generated in a step prior to etching, and forming a patterned topmost film for pattern etching.

[0032] As used herein, the term “processing” includes patterning, exposure, development, etching, deposition, cleaning, and / or removal of byproducts, as required when forming the described structure.

[0033] The term "deposit" or "deposition" refers to a series of processes in which material at the atomic or molecular level is deposited as a thin layer from a gaseous (vapor) state onto a wafer surface or substrate, transitioning from a gaseous to a solid state. Chemical reactions are involved in the process, either after the generation of a plasma containing reactive gases or after the reactive gases have been activated by heating. The plasma can be, but is not limited to, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron cyclotron resonance (ECR) plasma, or microwave plasma. Suitable commercially available plasma etching chambers include, but are not limited to, those branded with trademarks such as Flex™ or Tokyo Electron Tactras™ or Episode. TM UL sells the Lam Research Dual CCP reactive ion etching system's dielectric etching product line. Non-plasma exposure steps can be performed in a different chamber than the plasma exposure steps.

[0034] The term "aspect ratio" refers to the ratio of the height of a groove (or hole) to the width of the groove (or the diameter of the hole).

[0035] It should be noted that the terms “film,” “layer,” and “material” are used interchangeably herein. It should be understood that a film may correspond to or be associated with a layer or a material, and a layer may refer to both a film and a material. Furthermore, those skilled in the art will recognize that, as used herein, the terms “film,” “layer,” or “material” refer to a material of a certain thickness laid or spread on a surface, and that surface can range from as large as an entire wafer to as small as a trench or line.

[0036] It should be noted that in this document, the terms “aperture,” “via,” “hole,” “trench,” and “structure” are used interchangeably to refer to openings formed in a semiconductor structure.

[0037] As used herein, the abbreviation “NAND” refers to a “Negative AND or Not AND” gate; the abbreviation “2D” refers to a 2D gate structure on a planar substrate; and the abbreviation “3D” refers to a 3D or vertical gate structure in which gate structures are stacked in the vertical direction.

[0038] It should be noted that in this document, the terms "etching gas" and "etching agent" are used interchangeably when the etching gas is in a gaseous state at room temperature and ambient pressure. It should be understood that etching gas may correspond to or be associated with an etching agent, and the etching agent may refer to the etching gas.

[0039] The term "doping" is used interchangeably in processes that incorporate one or more elements into a membrane by various methods that can chemically or physically combine them, as well as in processes that intentionally incorporate atoms of different elements into a membrane composition. One or more elements can be interstitially or alternatively doped within the membrane.

[0040] This article uses the standard abbreviations of the elements in the periodic table. It should be understood that elements may be referred to by these abbreviations (e.g., Si for silicon, N for nitrogen, O for oxygen, C for carbon, H for hydrogen, F for fluorine, etc.).

[0041] A unique CAS registry number (i.e., "CAS") assigned by the Chemical Abstracts Service is provided to identify the specific molecule disclosed.

[0042] As used herein, the term "hydrofluorocarbon" refers to a saturated or unsaturated functional group containing only carbon, fluorine, and hydrogen atoms.

[0043] As used herein, the term "fluorocarbon" refers to a saturated or unsaturated functional group containing only fluorine and hydrogen atoms.

[0044] As used in this article, the term “GWP” refers to global warming potential, typically measured on a 100-year timescale and compared to CO2.

[0045] As used herein, “CO2 emissions” or “CO2 equivalent emissions” refers to a comparison between the GWP of C2H2F2 and gases like CF4 and CHF3 (common fluorocarbon and hydrofluorocarbon etching gases) and emissions from plasma etching processes.

[0046] In this document, a range may be expressed as from about one specific value and / or to about another specific value. When such a range is expressed, it should be understood that another embodiment is from that one specific value and / or to that other specific value, together with all combinations within said range. Any and all ranges listed herein include their endpoints (i.e., x = 1 to 4, or x in the range from 1 to 4, including x = 1, x = 4, and x = any number in between), regardless of whether the term "inclusive" is used.

[0047] In this document, references to "an embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described with respect to that embodiment may be included in at least one embodiment of the invention. The phrase "in an embodiment" appearing in different places in the specification does not necessarily refer to the same embodiment in all instances, and individual or alternative embodiments are not necessarily mutually exclusive with other embodiments. The same applies to the term "implementation."

[0048] As used herein, the term “exemplary” is used to mean serving as an instance, example, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as superior to or advantageous to other aspects or designs. Rather, the use of the term “exemplary” is intended to present the concept in a concrete manner.

[0049] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise stated or clear from the context, "X adopts A or B" is intended to mean any natural inclusive arrangement. That is, if X adopts A; X adopts B; or X adopts both A and B, then "X adopts A or B" is satisfied in any of the foregoing cases. Additionally, the article "a / an" as used in this application and the appended claims should generally be interpreted as meaning "one or more" unless otherwise stated or clearly indicated from the context to the singular form.

[0050] The term “comprising” in the claims is an open-ended transitional term, meaning that the subsequently defined claim elements are a non-exclusive list (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” is defined herein as necessary to encompass the more restrictive transitional terms “substantially consists of” and “consisting of”; therefore, “comprising” can be replaced by “substantially consists of” or “consisting of” and remain within the clearly defined scope of “comprising”.

[0051] In the claims, "provide" is defined as meaning to supply, provide, make available, or prepare something. The steps can, conversely, be performed by any actor even if not explicitly stated in the claims. Attached Figure Description

[0052] To further understand the nature and purpose of the present invention, reference should be made to the following detailed description in conjunction with the accompanying drawings, in which similar elements are given the same or similar reference numerals, and wherein: Figure 1 The FTIR spectrum is from the emissions of the CHF3 plasma etching process for etching SiO2 films; Figure 2 The FTIR spectrum is from the emissions of the C2H2F2 plasma etching process for etching SiO2 films; Figure 3 The etching rates are those of two etching gases (C2H2F2 and CHF3) in etching processes that etch SiO2 films with high and low plasma source power. Figure 4 It is the SiO2 etching rate as a function of N2 or O2 addition for C2H2F2 / Ar etching; Figure 5 It is the low-k dielectric etch rate used for C2H2F2 / Ar etching as a function of N2 or O2 addition; Figure 6 This is a comparison of the etching rates of CF4, CHF3, CF3I, and C2H2F2 for polycrystalline silicon films, SiO2 films, SiN films, and SOC films. Figure 7 This is a comparison of the selectivity of CF4, CHF3, CF3I, and C2H2F2 for polycrystalline silicon films, SiO2 films, SiN films, and SOC films; Figure 8 It is a mass spectrometer of pure CHF3; Figure 9 It is a mass spectrum of pure C2H2F2; and Figure 10 It is a mass spectrometer of pure CF4. Detailed Implementation

[0053] The method disclosed involves using hydrofluorocarbon etching gas C2H2F2 plasma to etch dielectric materials or layers and / or Si-containing materials or layers to form patterned structures for manufacturing semiconductor chips, such as back-end operations (BEOL) or interconnects (trench etching and via etching) for logic devices, and high-k etching (such as transistor and gate patterning, slot etching, patterned etching, recess etching, or mask penetration). The dielectric materials or layers can be silicon-containing layers such as SiO2, and low-k materials or layers (such as SiOCH films).

[0054] Conventional fluorocarbons and hydrofluorocarbons can have high global warming potential (GWP), and when exposed to plasma, they decompose and may form substances with high GWP as well. These high GWP substances are emitted. In some cases, even when byproducts are scrubbed, the scrubbing process may be incomplete because not 100% of the fluorinated substances are converted into CO2; furthermore, plasma and thermal scrubbers may even generate high GWP byproducts from these reactions.

[0055] Compared to commonly used hydrofluorocarbon (HFC) etching gases, the disclosed plasma etching method using C₂H₂F₂ with an inert co-reactant (such as N₂) achieves a reduction of at least 10% in CO₂ equivalent emissions from the reaction chamber. For example, compared to CF₄, the disclosed plasma etching method provides at least a 10% reduction in CO₂ equivalent emissions from the reaction chamber compared to using CF₄ as the etching gas. That is, CO₂ equivalent emissions from the reaction chamber using C₂H₂F₂ are at least 10% lower than CO₂ equivalent emissions using CF₄ as the etching gas.

[0056] As shown in Table 1, C2H2F2 is particularly attractive due to its very low GWP (< 1), while other conventional fluorocarbon and hydrofluorocarbon etching gases have very high GWPs, such as CH2F2 with a GWP of 677.

[0057] C2H2F2 has four major isomers listed in Table 2 below. The preferred C2H2F2 molecule is CAS number 75-38-7.

[0058] Table 2

[0059] C2H2F2 is supplied in cylinders in various filling volumes, pressures, and specifications. Preferably, the C2H2F2 in the cylinder has a low moisture content of < 40 ppm, more preferably < 10 ppm. C2H2F2 can be purified by distillation, adsorption via molecular sieves, or other existing methods to remove critical impurities such as other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFCs), impurities from the air such as N2, O2, CO2, moisture (H2O), HF, and other hydrocarbons such as CH4. Some impurities can form azeotropes; therefore, additional purification methods using chemical methods may be necessary to separate them.

[0060] The disclosed plasma etching method includes exposing a substrate in a reaction chamber to one of an etching gas C2H2F2 and / or its isomers, preferably C2H2F2 (CAS No.: 75-38-7), during the plasma etching process and / or during the chamber conditioning process.

[0061] The disclosed plasma etching method for selectively etching one or more dielectric films to form holes or structures by using a patterned mask layer deposited on top of one or more dielectric films in a substrate includes: The substrate is installed in the reaction chamber; An etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; and An etching reaction is allowed between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure.

[0062] The reaction chamber can be any accessory or chamber within the apparatus in which the etching method is performed, such as, but not limited to, reactive ion etching (RIE), CCP with a single or multiple frequency RF sources, inductively coupled plasma (ICP), microwave plasma reactors, or other types of etching systems capable of plasma processing (i.e., selectively removing a portion of the dielectric film or generating active material or depositing a film).

[0063] The reaction chamber is equipped with a parallel-plate electrode plasma generator, in which a 60 MHz high-frequency electromagnetic field is applied to the upper electrode and a 2 MHz electromagnetic field is applied to the lower electrode, with the gap between the electrodes maintained in the range of 10 to 35 mm. This combination of electric fields allows power in the range of 0-2000 W to be applied to the upper electrode and power in the range of 1500-7000 W to be applied to the lower electrode. The plasma can be generated with a total RF power ranging from about 25 W to about 100 kW. The plasma can be generated remotely or within the reaction chamber itself. The RF frequency of the plasma can range from 100 kHz to 1 GHz. The plasma can be pulsed or continuous wave. In some embodiments, the power applied to the chamber can range from 0 to several kW of bias power and hundreds to thousands of kW of source power.

[0064] The temperature and pressure within the reaction chamber are maintained under conditions suitable for the reaction of the process film with the activated etching gas C₂H₂F₂. For example, depending on the etching parameters required, the pressure in the chamber can be maintained between approximately 0.1 mTorr and approximately 1000 Torr, preferably between approximately 1 mTorr and approximately 10 Torr, more preferably between approximately 10 mTorr and approximately 1 Torr. In some embodiments, the pressure in the chamber can range from 1 mTorr to several hundred mTorr. In the case of introducing an etching gas mixture, the pressure in the etching chamber is maintained between 15 and 30 mTorr during the plasma etching process. Similarly, the substrate temperature or the temperature range of the reaction chamber can range from -20°C to 300°C, although lower temperatures ranging from -20°C to -196°C are possible. The reaction chamber wall temperature can be approximately > -20°C, preferably < 300°C. Depending on the process requirements, the reaction chamber wall temperature can be approximately room temperature or above room temperature but less than 300°C. In some embodiments, the substrate temperature range in the reaction chamber can be 20°C to 200°C.

[0065] One or more additional hydrofluorocarbon or fluorocarbon etching gases can be added to C2H2F2. These additional hydrofluorocarbon etching gases can be selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, and C4F... 10 C5F8, or C6F6, C7F 14 C7F 16 or C8F 16 The additional one or more hydrofluorocarbon etching gases can be selected from C1-C6 hydrofluorocarbons. x F y H zMolecules (x, y, and z are integers, 1 ≤ x ≤ 8) selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F 10 C5HF7, or combinations thereof.

[0066] Referring to Table 1, some hydrofluorocarbons (HFCs) or fluorocarbons have higher gas-to-oil (GWP) values ​​compared to C₂H₂F₂. To improve etching performance and quality, one or more HFCs or fluorocarbons can be added to C₂H₂F₂ to slightly adjust etching performance. When adding small amounts of HFCs or fluorocarbons with high GWP values, the total CO₂ equivalent emissions from the reaction chamber may not have a significant impact considering the improved etching performance. For example, adding one or more HFCs or fluorocarbons relative to less than 10% of C₂H₂F₂ may not significantly change the CO₂ equivalent emissions from the reaction chamber compared to the significantly improved etching performance. In practice, a balance may need to be struck between reducing CO₂ equivalent emissions and achieving high etching performance.

[0067] Other gases (such as additives) can be added to C2H2F2. These additives include H2, SF6, NF3, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, or HF.

[0068] Co-reactants (such as inert gases) can also be added to the etching gas C2H2F2. The inert gas is selected from He, Ar, Kr, Xe, Ne, N2, or combinations thereof. In some embodiments, N2, Ar, or a combination of both can be added to C2H2F2. The combination of N2 and Ar can have any ratio ranging from 0% to 100%. The flow rate range of C2H2F2, N2, and Ar can be from 1 sccm to 10 slm, preferably greater than 10 sccm and less than 1 slm. Different C2H2F2 / N2 / Ar flow rate ratios can be applied. Here, N2 and / or Ar can be replaced by other inert gases (such as Kr, Xe, Ne, He, or combinations thereof). In some embodiments, N2 can be added to C2H2F2. In some embodiments, Ar can be added to C2H2F2.

[0069] Etching processes can be continuous or cyclic. For cyclic etching, such as atomic layer etching, the etchant is Ar in the plasma etching step and C2H2F2 is the precursor in the deposition step. During the deposition step, the source plasma power is on and the bias power is off. For the etching step, both the source power and the bias power are on, generating a mixture of gaseous byproducts leaving the plasma etching chamber, which has a lower GWP compared to processes using conventional fluorocarbon etching gases such as CF4 or CHF3.

[0070] The C2H2F2 etching step can be performed independently on the already exposed dielectric substrate, or it can be a step in a longer overall etching scheme that includes a mask opening step, a lower layer penetration etching step, or a post-etch cleaning step. Various advanced process control mechanisms can be employed for the C2H2F2 etching process, including but not limited to wafer-sequence-based etching time or flow rate corrections to account for cross-batch effects; time or flow rate corrections based on preventative maintenance (PM) cycles to account for cross-PM effects; pre-batch or intermediate-batch chamber aging to account for cross-batch effects; post-wafer-batch chamber cleaning to reset chamber conditions; OES-based endpoint corrections for landed etch; and feedforward or feedback-based time or flow rate corrections to control the depth or CD of etched features.

[0071] The substrate contains a dielectric material or film, such as SiO2 or SiOCH. An example is a dielectric film layer used in interconnect metal layers. The dielectric film comprises a layer of SiO or SiOCH. The dielectric film or material includes one or more Si... a O b H c C d N e Layers, wherein a > 0, b, c, d, and e ≥ 0, are selected from silicon oxide, silicon nitride, crystalline Si, polycrystalline silicon, polycrystalline silicon, amorphous silicon, and low-carbon silicon. k SiCOH, SiOCN, SiC, SiON.

[0072] The materials to be etched include silicon-containing films such as SiO2, carbon-containing SiO2 such as low-k dielectric SiOCH (formed by PECVD, spin-coating deposition, or other methods), crystalline Si and polycrystalline silicon, SiN, metals and their oxides (Ti, Pt, W, Al), mask materials (including organic-based materials such as photoresists), spin-coated carbon, amorphous carbon, nitrides (such as SiN and TiN), and metals and their oxides (Ti, Pt, W, Al). Preferably, the material to be etched is a low-k dielectric material such as SiO2 or SiOCH.

[0073] Here, the SiO film can include, but is not limited to, films containing Si, O, C, B, N, and H deposited using CVD (with or without plasma), spin-coating, or other methods. The silicon-containing film can also be a silicon oxide-based dielectric material, such as organic-based or silicon oxide-based low-k dielectric materials, such as Applied Materials, Inc.'s Black Diamond I, II, or III materials (with the formula SiOCH). The silicon-containing film may also include Si a O b N c Where a, b, and c range from 0.1 to 6. Silicon-containing films may also include dopants such as B, C, P, As, and / or Ge. The film can be porous with a wide range of pore sizes.

[0074] On top of the dielectric film or material is a mask layer or mask material. The mask material can be amorphous carbon, doped amorphous carbon, SOC (spin-on carbon), Si, SiN, Al, AlO, Ti, TiO, other metal and metal oxide masks, or other nitride layers (such as TiN) with or without dopants.

[0075] C2H2F2 is supplied in cylinders in various filling volumes, pressures, and specifications. Preferably, the material has a low moisture content of < 40 ppm, more preferably < 10 ppm. C2H2F2 can be purified by distillation, adsorption using molecular sieves, or other common and known methods in the art to remove critical impurities such as chlorinated substances or organochlorides, other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFCs), impurities from the air (N2, O2, CO2), moisture (H2O), HF, and other hydrocarbons (CH4, etc.). Some impurities can form azeotropes, therefore, other purification methods may be required to separate them using chemical means. The primary application of the disclosed plasma etching method is to selectively plasma etch silicon-containing layers such as SiO2 or SiOCH using C2H2F2 and N2 or C2H2F2, N2, and Ar with masks such as nitrides (like SiN or TiN) or carbon (e.g., amorphous carbon or SOC) to fabricate semiconductor devices and reduce CO2eq (CO2 equivalent) GWP emissions from the etching process. C₂H₂F₂ not only has a much lower gas volatile protein (GWP) than standard or commonly used fluorinated etching gases, it also produces lower GWP emissions from etching processes than those using standard fluorinated etching gases such as CF₄. This type of etching process is typically used in downstream dielectric etching processes to form trenches, vias, and spacers to fabricate logic devices. C₂H₂F₂ and N₂, or C₂H₂F₂, N₂, and Ar, can also be used to manufacture memory devices and a wide variety of other semiconductor devices.

[0076] The disclosed plasma etching method uses C2H2F2 as the etching gas to etch dielectric films, thereby creating holes in the silicon-containing films, such as channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, contact etching areas, slit etching areas, self-aligned contacts, self-aligned vias, and supervias. The size range of the etched structures can be patterned features from nm to cm, with a vertical depth from nm to mm. Applications range from pattern transfer (e.g., three-layer etching, pitch doubling, etch stop penetration), dielectric etching (trenches, vias, contacts) to small features (gate, source, drain patterning) to large features (through silicon vias, memory channels). Structures can be, but are not limited to, trenches, holes, plugs, etc.

[0077] The disclosed plasma etching method is not limited in any way to the experimental conditions described above. The type of plasma etching tool (e.g., capacitively coupled or inductively coupled plasma), process conditions (e.g., pressure, power, temperature, process duration), process gas mixture, combination and proportion of gases in the process gas mixture, gas flow rate, workpiece, and plasma etching chamber itself can be varied for each process and during the process.

[0078] In summary, the disclosed plasma etching method provides enhanced control over the deposition profile of polymer films using C2H2F2, as well as the ability to etch dielectric materials with high etch rates and selectivity. Furthermore, C2H2F2 has a lower gas efflux potency (GWP) than commonly used gases such as CF4, CHF3, C4F8, and CH2F2, enabling a more eco-friendly process; for example, CO2 equivalent emissions from the reaction chamber using C2H2F2 are at least 10% lower than those using CF4 as the etching gas.

[0079] Example

[0080] A more detailed description of the disclosed method is provided below with examples. However, the disclosed method is not limited in any way to the examples presented, and the process conditions, process gas mixtures, the combination and proportion of gases in the gas mixture, the workpiece, and the plasma etching chamber itself can be varied.

[0081] In the following examples, the primary plasma etching source can be CCP plasma, but other sources such as ICP, microwave, ECR, etc., may also be included. The plasma can be used as a continuous source or as a pulsed plasma with a specific frequency and duty cycle. Additional fluorocarbon gases can be added to slightly adjust the etching performance. Additional inert gases such as Kr, Xe, Ne, and hydrogen source gases such as H2, as well as hydrocarbons, can be added. Mask materials can include TiN or other metal nitride materials, SiN, Si, carbon materials, etc.

[0082] Example 1: FTIR of emissions from CHF3 plasma etching process

[0083] FTIR was measured from emissions from a CHF3 plasma etching process that etches SiO2 films, and the FTIR spectra are shown in... Figure 1 The process conditions are as follows: temperature 20°C / 150°C ESC / UEL (electrostatic chuck or wafer temperature / upper electrode); plasma source power 500 W source plus 150 W bias; pressure 20 mTorr; and CHF3 / N2 flow rate 20 / 80 sccm for 60 s. As shown, the main emitted substances are SiF4, CHF3, CF4, CO, CO2, and HF.

[0084] Example 2: FTIR of emissions from a C2H2F2 plasma etching process

[0085] FTIR was measured from the emissions of the C2H2F2 plasma etching process for etching SiO2 films, and the FTIR spectra are shown in... Figure 2 The process conditions are as follows: temperature 20°C / 150°C ESC / UEL (electrostatic chuck or wafer temperature / upper electrode); plasma source power 500 W source plus 150 W bias; pressure 20 mTorr; and C2H2F2 / N2 flow rate 20 / 80 sccm for 60 s. As shown, the main emitted substances are SiF4, CHF3, CF4, CO, CO2, and HF. (The last sentence appears to be incomplete and possibly refers to a process involving the release of SiF4, CHF3, CF4, CO, CO2, and HF.) Figure 1 and Figure 2 The comparison shows that the CHF3 and CF4 peaks in the C2H2F2 spectrum are much smaller than those in the CHF3 spectrum, indicating that the emissions from C2H2F2 have a much lower GWP.

[0086] Example 3: C2H2F2 and CHF3 Plasma Etching Process

[0087] Two different source powers of 2000 W and 500 W were used with a bias power of 100 W in a 300 mm dielectric CCP etching tool at pressures of 25 mTorr and 5 mTorr. Two etching gases (C2H2F2 and CHF3) were evaluated in the etching process of SiO2 films. The results are shown in… Figure 3The etching compositions comprise C2H2F2, Ar, and N2, or CHF3, Ar, and N2, respectively. The flow rate of C2H2F2 or CHF3 is 15 sccm. The flow rates of Ar and N2 are each 52.5 sccm. The wafer temperature is 20°C. The high voltage is 25 mTorr and the low voltage is 5 mTorr. As shown, the selectivity of C2H2F2 with N2 and Ar relative to the TiN mask material for etching SiO2 is higher than that of CHF3 with N2 and Ar. O2 is not used in the etching process. Traditionally, O2 is used as a co-reactant in plasma etching processes to control polymerization. However, based on Figure 3 The results showed that N2 effectively controlled the polymerization with C2H2F2. Good selectivity relative to the mask material (like TiN) was achieved for each etching composition, thus the polymerization was controlled in the absence of O2 by adding N2 and Ar. For CHF3, the selectivity for etching SiO2 relative to TiN was 46 at a low source power of 500 W, and for C2H2F2, the selectivity was 70. Therefore, a much higher selectivity was observed when using C2H2F2 instead of CHF3, with a selectivity increase of 52%. For CHF3, at a high source power of 2000 W, the selectivity for etching SiO2 relative to TiN was 28, and for C2H2F2, the selectivity was 44, representing a 57% increase in selectivity, as shown in Table 3. As shown, C2H2F2 / N2 / Ar maintained higher selectivity than the equivalent composition using CHF3 at both low and high source power.

[0088] Table 3

[0089] Example 4: Etching with C2H2F2 using N2 or O2

[0090] The SiO2 etching rate was evaluated using C2H2F2 as a function of O2 and N2 under different plasma and flow conditions. The conditions were as follows: Plasma RF source power varied from 400 W to 800 W, with a bias power of 150 W. The pressure was 10 mTorr, and the C2H2F2 flow rate was 15 sccm. The flow rates of O2, Ar, and N2 were adjusted. The wafer temperature was 20°C. At a C2H2F2 flow rate of 15 sccm, 10 sccm of O2 was required to achieve an etching rate of approximately 35 nm / min. However, without O2 and with the addition of 40 sccm of N2, the SiO2 etching rate was approximately 55 nm / min. Therefore, by adding N2 instead of O2, the SiO2 etching rate was significantly higher in the case of C2H2F2, as shown below. Figure 4 As shown in the image. Figure 5The low-k etch rate is a function of the O2 flow rate. The etch rate with added O2 is similar to that with N2 up to 10 sccm; however, at higher flow rates, the etch rate with added O2 is faster than with N2.

[0091] Example 5: C2H2F2 etching compared to CF4, CHF3, and CF3I

[0092] The etching rates and selectivity of four different fluorocarbon etching gases (C2H2F2, CF4, CHF3, and CF3I) were measured under similar etching conditions in a 300 mm CCP plasma etching tool. This comparison includes two very high GWP gases (CF4 and CHF3) and two low GWP gases (CF3I and C2H2F2). The results are shown in... Figure 6 and Figure 7 The process conditions were as follows: temperature 20°C / 150°C ESC / UEL; plasma source power 500 W source + 150 W bias; pressure 20 mTorr; etching gas flow rate 20 sccm for 60 s; N2 flow rate 80 sccm N2 for 60 s. Under these conditions, C2H2F2 exhibited the highest SiO2 etching rate and the highest selectivity relative to SOC (spin-on carbon mask) etching of SiO2. Therefore, compared to both lower and higher GWP gases, the lower GWP gas C2H2F2 provided improved etching performance.

[0093] Example 6: Emissions from CF4, CHF3, and C2H2F2 etching processes

[0094] Emissions from CF4, CHF3, and C2H2F2 etching processes for etching SiO2 films were measured using a 300 mm plasma etching tool. For each gas, the experimental conditions were the same: temperature 20°C / 150°C ESC / UEL; plasma source power 500 W source + 150 W bias; pressure 20 mTorr; and flow rate 20 sccm for the etching gas and 80 sccm for N2 for 60 s. Emissions from equivalent etching rate processes among C2H2F2, CF4, and CHF3 were quantified. The CHF3 process was found to have 1.87E-04 g / wafer CO2eq (CO2 equivalent) emissions, the CF4 process 4.61E-04 CO2eq emissions, and the C2H2F2 process 3.88E-05 g / wafer. The CO2eq emissions of C2H2F2 are only 20% (80% reduction) of those of the equivalent CHF3 process and 8% (92% reduction) of those of CF4. Therefore, C2H2F2 not only provides improved selectivity relative to TiN and SOC etching of SiO2, but also significantly reduces CO2eq emissions. This indicates that C2H2F2 has both lower GWP and lower GWP emissions compared to CHF3 and / or CF4.

[0095] Example 7: Mass spectra of CF4, CHF3, and C2H2F2 etchings

[0096] Mass spectra of each of the gases CF4, CHF3, and C2H2F2 were compared using a Hiden mass spectrometer as a function of electron volts (eV). The spectrum of pure CHF3 was evaluated and is presented. Figure 8 The mass spectrum of C2H2F2 is shown in the figure. Figure 9 The mass spectrum of CF4 is shown in the figure. Figure 10 As shown, the mass spectra of each molecule are quite different. C2H2F2 is dominated by C2H2F (C / F ratio of 2); CHF3 is dominated by CF3 (C / F ratio of 0.3), followed by CHF2 (C / F ratio of 0.5). Therefore, compared to CHF3, C2H2F2 produces larger and more carbon-rich fragments that could contribute to improved selectivity. On the other hand, CF4, as expected, produces predominantly CF3, an etchant with minimal polymerization protection properties.

[0097] Example 8: Deposition of CH2F2, C4F8, CHF3, and C2H2F2

[0098] The deposition rates of different fluorocarbon gases were compared by introducing a gas at 15 sccm along with Ar at 250 sccm and a plasma source power of 750 W, as well as unbiased power, into a 200 mm CCP plasma etching tool. No O2 was introduced into the etching tool. As shown in Table 4, C2H2F2 provided an increased polymer deposition rate, which is beneficial for sidewall protection in patterning processes. Data from previous examples also demonstrate that adding N2 to control the polymerization of C2H2F2 is highly effective in overcoming the increased polymer deposition rate compared to CHF3.

[0099] Table 4

[0100] Example 9: Etching rates of SiO2, low-k, and TiN using C2H2F2

[0101] The etching rates of SiO2, low-k, and TiN were evaluated using a 300 mm CCP plasma etching tool under different temperatures, pressures, plasma powers, and Ar / N2 flow ratios. Table 5 shows the conditions and results for three experiments. As shown, low-k etching is slightly faster than SiO2 etching, resulting in higher selectivity for low-k etching relative to TiN mask materials. Therefore, SiO2 is a good representative film for a variety of commercially available low-k films. Moreover, the etching rate can be highly dependent on temperature and plasma power.

[0102] Table 5

[0103] It should be understood that many additional changes in details, materials, steps, and arrangements of parts that have been described and elucidated to explain the nature of the invention can be made by those skilled in the art within the principles and scope of the invention as set forth in the appended claims. Therefore, the invention is not intended to be limited to the specific embodiments given above and / or in the drawings.

[0104] Although embodiments of the invention have been shown and described, those skilled in the art can modify them without departing from the spirit or teachings of the invention. The embodiments described herein are exemplary only and not limiting. Many variations and modifications of the compositions and methods are possible and are within the scope of the invention. Therefore, the scope of protection is not limited to the embodiments described herein, but is defined only by the following claims, the scope of which should include all equivalents of the subject matter of the claims.

Claims

1. An etching method for forming a structure by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; as well as An etching reaction is allowed between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure.

2. The method of claim 1, further comprising: One or more hydrofluorocarbon or fluorocarbon etching gases are added to C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F... 10 C5F8, or C6F6, C7F 14 C7F 16 or C8F 16 The one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbons. x F y H z A molecule, where x, y, and z are integers, 1 ≤ x ≤ 8, selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F 10 C5HF7, or combinations thereof.

3. The method of claim 1, further comprising: An additive is added to C2H2F2, wherein the additive is selected from H2, SF6, NF3, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, or HF.

4. The method of claim 1, further comprising: A co-reactant is added to C2H2F2, the co-reactant being an inert gas selected from the following: Ar, Kr, Xe, Ne, N2, He, or a combination thereof.

5. The method of claim 1, further comprising: The co-reactant N2 is added to C2H2F2.

6. The method according to any one of claims 1 to 5, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 75-38-7.

7. The method according to any one of claims 1 to 5, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number: 1630-78-0.

8. The method according to any one of claims 1 to 5, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 1630-77-9.

9. The method according to any one of claims 1 to 5, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 1691-13-0.

10. The method according to any one of claims 1 to 5, wherein, The one or more dielectric films are SiO2 films and SiCOH films.

11. The method according to any one of claims 1 to 5, wherein, The CO2 equivalent emissions from this reaction chamber are at least 10% lower than the CO2 equivalent emissions when using CF4 as the etching gas.

12. An etching method for forming a structure with low CO2 equivalent emissions by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; as well as This allows an etching reaction to occur between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure. The CO2 equivalent emissions from this reaction chamber are at least 10% lower than the CO2 equivalent emissions when using CF4 as the etching gas.

13. The method of claim 12, further comprising: One or more hydrofluorocarbon or fluorocarbon etching gases are added to the etching gas C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F6, C4F6, C2F4, C3F6, C4F6, C4F6, C2F4, C3F6, C4F6, C2 ... 10 C5F8, C6F6, C7F 14 C7F 16 or C8F 16 The one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbons. x F y H z A molecule, where x, y, and z are integers, 1 ≤ x ≤ 8, selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, and C5F. 10 C5HF7, or combinations thereof.

14. The method of claim 12, further comprising: An additive is added to C2H2F2, wherein the additive is selected from H2, SF6, NF3, NH3, Cl2, BCl3, BF3, Br2, F2, FNO, FNO3, HBr, HCl, HI, IF5, IF7, or HF.

15. The method of claim 12, further comprising: A co-reactant is added to C2H2F2, the co-reactant being an inert gas selected from the following: Ar, Kr, Xe, Ne, N2, He, or a combination thereof.

16. The method according to any one of claims 12 to 15, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 75-38-7.

17. An etching method for forming a structure by selectively etching one or more dielectric films on top of a patterned mask layer deposited in a substrate, the method comprising: The substrate is installed in the reaction chamber; An etching composition containing a gas mixture of C2H2F2 and an inert gas is introduced into the reaction chamber; The etching composition is converted into plasma; as well as This allows an etching reaction to occur between the plasma and the one or more dielectric films, such that the one or more dielectric films are selectively etched relative to the patterned mask layer to form the structure. The temperature range of the substrate is -20°C to 300°C.

18. The method of claim 17, wherein, The inert gas is selected from Ar, Kr, Xe, Ne, N2, He or a combination thereof.

19. The method of claim 17, wherein, The inert gas is selected from N2, Ar, or a combination of both, with each combination having any ratio ranging from 0% to 100%.

20. The method according to any one of claims 17 to 19, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 75-38-7.

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