Etching method for forming a structure by etching dielectric films

Abstract

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 includes: mounting the substrate in a reaction chamber; introducing an etching gas containing C2H2F2 into the reaction chamber; converting the etching gas into a plasma; and allowing 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.

Description

Technical Field

[0001] The present invention relates to a method for etching dielectric materials using hydrofluorocarbon etching gas C2H2F2 plasma to manufacture semiconductor wafers, such as for back-end-of-line (BEOL) interconnects (trench etching and via etching) of logic devices. Prior Art

[0002] Conventional plasma etching gases used in the manufacture of semiconductor devices are typically fluorocarbon or hydrofluorocarbon gases used to etch silicon-containing materials such as SiO2, SiN, SiOCH, etc. However, the fluorocarbon and hydrofluorocarbon gases used generally have high global warming potential (GWP). [surface] [1] Includes the GWP of commonly used etching gases in the semiconductor industry along with other molecules that may be plasma byproducts and other chemicals. Conventional etching gases used for etching back-end-of-line (BEOL) dielectric materials such as low-k films are CF4 or CHF3, while other fluorocarbon gases can be used for SiO dielectric etching, including C4F8 or CH2F2. As can be seen from the table, the GWP of CF4 (6630) and CHF3 (12400) are extremely high. Therefore, these molecules are detrimental to global warming issues. Other commonly used fluorocarbons or hydrofluorocarbons may include CH2F2, CH3F, C4F8, C4F6, C2F6, C3F8, etc. In addition, byproducts from etching may include NO2, CO, CO2, COF4, SiF4, etc. [[] [surface] [1] gas GWP 100 CHF 3 12400 C 2F 6 11100 C 4F 8 9540 CF 4 6630 CH2F2 677 NO 2 265 CO 2.1 CO 2 1 COF 2 < 1 CF 3I < 1 C 4F 6 < 1 C 2H 2F 2 < 1

[0003] However, the principle of plasma etching is that molecules are fragmented by the energy and collisions of the plasma, breaking bonds, producing byproducts, etching the substrate, generating reaction byproducts, and the fragments recombine to form new substances. Therefore, plasma fragmentation and chemical composition are extremely complex and difficult to predict. Therefore, while the molecules entering the plasma may themselves have a high GWP, the GWP of the emissions leaving the plasma etching tool is determined by the fragmentation of the molecules and the resulting recombination and byproducts. When the gases leave the plasma etching tool, they flow through a vacuum pump, are diluted with nitrogen, and often pass through a scrubber. Scrubbers are generally of two types. The first type is a plasma device that further decomposes the molecules. The second type is a burner, which typically burns the emissions by adding a substance such as methane. Both types of scrubbers decompose etching byproducts. Plasma devices use RF energy, while burners use heat. Further abatement can be performed using wet or dry scrubbers to remove substances such as HF or other toxic materials. The challenge is that C-F bonds are very strong and difficult to remove. Therefore, while it's important to use an etchant gas system with a low GWP, it's also important to have the exhaust gas have a low GWP. This is especially true for lower plasma power processes like BEOL dielectric etch, where the lower source power of the etch tool may not fully dissociate the incoming molecules. Therefore, if the incoming etchant molecules have a high GWP, a high proportion of undissociated gases will exit the chamber, and thus will have high-GWP emissions or high CO₂ equivalent emissions.

[0004] SiO and SiOCH materials are used as insulating films in semiconductor wafer fabrication. Various SiO and SiOCH film compositions are used (often containing other elements such as nitrogen, hydrogen, and boron). The etching characteristics of SiOCH films are generally similar to those of SiO films using fluorocarbon etching gases. The mask used in the patterning process can also vary. For example, when etching SiO and SiOCH films, films such as TiN, carbon (amorphous carbon or spin-on carbon), and SiN are commonly used as mask materials. 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. Polymer formation occurs by fragmenting etching molecules in the plasma to form various free radical structures, which recombine on the surface to form the polymer material. Etching of silicon materials primarily results from the formation of volatile SiF₄ by F⁻ species. The polymer plays a key role in protecting the surface from ion bombardment and chemical attack from the plasma, while also providing F* to etch Si. The chemical structure is critical for the formation of different species in the plasma that drives the formation of polymers and etching species, and will also affect the GWP of emissions from plasma etchers.

[0005] Therefore, chemical structure is critical to both etching performance and global warming impact (both the GWP of the molecule and the GWP of emissions from the process). It is difficult to predict the etching performance and emissions of fluorocarbon molecules.

[0006] US 20160118266 discloses a method for manufacturing a semiconductor device, comprising forming a first etching layer and a second etching layer stacked on a substrate, and etching the first and second etching layers under plasma to form a recessed region. The etching gas comprises a compound represented by Formula I or II. The compound comprises 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, 1,1,2,2-tetrafluoro-1-iodoethane, 2,3,3,3-tetrafluoropropylene, and 1,1-difluoroethylene (which does include the use of C₂H₂F₂ in the plasma etching process).

[0007] US 2020234962 discloses a dry etching gas composition containing a saturated or unsaturated hydrofluorocarbon compound (excluding 1,2,2,3-pentafluorocyclobutane and 1,1,2,2-tetrafluorocyclobutane) represented by the following general formula (1): C xH yF z, wherein x, y, and z are integers satisfying 2 ≤ x ≤ 4, y + z ≤ 2x + 2, and 0.5 < z / y < 2. Among many different molecules, C 2H 2F 2 is listed in the examples together with an oxidizing agent used in the scheme.

[0008] KR 970023632 discloses a polymer patterning method using polymer deposition, wherein one of the reaction gases (C4F8, CHF3, CF4, C2F4, C2F6, C2F6) used to form a carbon polymer using a gas containing HBr, CCl4, C2H2F2, and C2HF5 is BCl3. KR 970023632 discloses C2H2F2, which includes CHF3 (known as a poorly performing etchant with a high global warming potential), in addition to other gases. The document also includes the addition of other gases such as BCl3 or HBr. []

[0009] US Pat. No. 5,814,563 discloses a method for etching dielectrics and other films such as TiN. The composition comprises C₂H₂F₂, an etchant such as CF₄, a nitrogen-containing gas such as NH₃, and an oxidant such as CO and / or Ar for sputtering. The NH₃-generating gas system is a gas capable of generating NH₃-containing substances, such as gases containing NH₂-, NH₃-, or NH₄+ ions or molecules, including, for example, NH₃, NH₄OH, CH₃NH₂, C₂H₅NH₂, C₃H₄NH₂, and mixtures thereof. Among these gases, NH₃ is preferred.

[0010] KR 19980085478 A discloses an etching method for forming contact holes using a reactive ion etching (RIE) method, wherein the conditions are: CF 4100-2000 sccm, CHF 3100-2000 sccm, C2H2F 2100-2000 sccm, RF (radio frequency) power 200-3000 W, pressure 100-2000 mT, and cathode temperature -40°C-40°C.

[0011] US 2007184605 discloses a method for manufacturing a flash memory device. A dry etching process is used under conditions that generate excess polymer to control 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 include transition metals, preferably Ni. The disclosed etching composition includes C2H2F2, C4F6, C4F8, or C5F8, Ar, and O2, but does not mention N2.

[0012] US 2009114944 discloses processing a substrate to form an LED device, including etching through a mask, wherein the etchant comprises a gas selected from a list including C₂H₂F₂ and an oxygen-containing gas. N₂ is not mentioned. The list of gases includes CF₄, CHF₃, C₂H₂F₂, or C₂F₃Cl₃.

[0013] US 2009155731 discloses a method for mitigating pattern defects, such as critical dimension (CD) deviation 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 a hydrofluorocarbon. For example, the process gas may include CHF₃, CH₂F₂, C₂HF₅, C₂H₂F₂, or C₂H₄F₂ as initial components, or any combination of two or more thereof. Furthermore, the process gas may further include a fluorocarbon gas, a hydrocarbon gas, or both as initial components. Furthermore, the process gas may further include an inert gas, such as a noble gas, as initial components. In addition, 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 an initial component.

[0014] US 2011272813 discloses a method for manufacturing a semiconductor device, comprising: forming a cap insulating film containing Si and C on a substrate; forming an organic silicon dioxide film on the cap insulating film, the film having a carbon-to-silicon ratio higher than that of the cap insulating film; and forming two or more concave portions having different opening diameters in the organic silicon dioxide film by plasma processing using a mixed gas comprising an inert gas, a nitrogen-containing gas, a fluorocarbon gas, and an oxidant gas. The method describes the use of a mixed gas comprising an inert gas, a nitrogen-containing gas, a fluorocarbon gas, and an oxidant gas. The fluorocarbon 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 amine gases. The purpose is to etch a low-k type silicon-containing film. The oxidant gas may be O₂, CO₂, CH₃OH, C₂H₅OH, C₃HₐOH, N₂O, NO, N₂O₃, NO₂, N₂O₄, or N₂O₅. The hard mask material is SiO₂. The cap insulating film is a film made of either silicon carbide (SiC) or silicon carbonitride (SiCN), or a laminated film thereof. Alternatively, the cap insulating film may be a film made of oxy-silicon carbide (SiCON) (which contains unsaturated hydrocarbons, amorphous carbon, and oxygen), or a laminated film of SiCN, SiC, and oxy-silicon carbide films.

[0015] US 2009111275 discloses a plasma etching method that prevents residue from adhering to the bottom and sides of vias and trenches. An interlayer insulating film formed of CwFx (x and w are predetermined natural numbers) and a metal layer or metal-containing layer formed on a substrate are simultaneously exposed to plasma generated by a process gas. The process gas system includes a mixture of CyFz (y and z are predetermined natural numbers) gas and N2 gas, with the flow rate of the N2 gas in the process gas being higher than the flow rate of the CyFz gas. The process gas system is CyFz (a non-hydrogen-containing gas), but in some cases, H-containing gases are mentioned. For example, CF4 is used as the fluorocarbon-based gas (CyFz (y and z are predetermined natural numbers) gas) contained in the process gas. The fluorocarbon-based gas contained in the process gas is not limited thereto and may be C4F8, C2F6, C3F8, C4F6, or C5F8. If CHF 3 is used as the hydrogen-containing gas or NF 3 or SF 6 is used as the non-carbon-containing gas, the same effects as those of the present invention can be expected.

[0016] US 2005186801 discloses a method for manufacturing a semiconductor integrated circuit device having a damascene interconnect structure by embedding a conductor film into a recess (such as a trench or hole) formed in an organic insulating film. The organic insulating film constitutes an interlayer dielectric film and contains an organosiloxane as a main component. The recess (such as a trench or hole) is formed by subjecting the organic insulating film to plasma dry etching in a CF-based gas / N₂ / Ar gas atmosphere to suppress the formation of an abnormal shape at the bottom of the recess when a photoresist film is formed on the organic insulating film, and then forming the recess therein with the photoresist film serving as an etching mask. Gases such as CHF₃, CF₄, CH₂F₂, or C₅F₂ can be used. Furthermore, saturated cyclic fluorocarbons (such as C₃F₆), unsaturated cyclic fluorocarbons (such as C₅F₆), acyclic fluorocarbons (such as CF₄, CHF₃, or CH₂F₂), or fluorocarbon iodides (such as CF₃I), developed as a countermeasure against freons, can be used as the CF₃ gas. For example, SF₆ can be used instead of the CF₃ gas. The dielectric can be an organic spin-on-glass material. An example is provided using a C₄F₆ / N₂ / Ar etching scheme. FIG9 shows that increasing the N₂ flow rate increases the etch rate of organic SOG, and the etch selectivity relative to SiN increases (maximum at an N₂ flow rate of 200 sccm (Ar flow rate of 420 sccm, resulting in a ratio of approximately 0.5)) and decreases at higher N₂ flow rates. It is also described that useful etch selectivities and etch rates are obtainable at nitrogen flow rates ranging from 150 sccm (C / N ratio: 0.16) to 300 sccm (C / N ratio: 0.08), which can be widened to a range of 50 sccm (C / N ratio: 0.48) to 500 sccm (C / N ratio: 0.48).

[0017] US 2014363975 discloses a cyclic etching process, wherein the deposition gas is selected from C 4 F 8, C 2 F 4, C 2 H 2 F 2 and CCl 4, and there is an etching gas selected from CF 4 and SF 6, the chlorine-based etching gas includes Cl 2, BCl 3, SiCl 4, SiCl 2H 2, and the bromine-based etching gas includes Br 2 and HBr.

[0018] Conventional fluorocarbon and hydrofluorocarbon gases can have high global warming potentials (GWPs), and when exposed to high-power plasma, they decompose and potentially form substances with high GWPs. These high-GWP substances are then emitted. In some cases, these high-GWP substances can pass through scrubbers, but these high-GWP substances have varying efficiencies. Therefore, there is a need for both lower-GWP etching gases that are effective in etching dielectric materials and gases that decompose in plasma and produce lower-GWP byproducts (compared to the traditional fluorocarbon and hydrofluorocarbon gases used in the semiconductor industry).

[0019] Therefore, there is a need for both lower GWP etching gases than those of commonly used hydrofluorocarbon and fluorocarbon etching gases (e.g., CF 4 ) that function in etching processes and gases that decompose in plasma and produce lower GWP byproducts than those of commonly used hydrofluorocarbon and fluorocarbon etching gases. Summary of the Invention

[0020] An etching method for forming a structure by selectively etching one or more dielectric films using a patterned mask layer deposited on top of the one or more dielectric films in a substrate is disclosed, the method comprising: Mounting the substrate in a reaction chamber; The etching gas containing C 2H 2F 2 is introduced into the reaction chamber; converting the etching gas into plasma; and An etching reaction is allowed to occur between the plasma and the one or more dielectric films, so 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 include: 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, C4F10, C5F8, or C6F6, C7F14, C7F16, or C8F16, wherein the one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbon CxFyHz molecules, wherein x, y and z are integers, 1 ≤ x ≤ 8, and the molecules are selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H 2F 6, C 3H 4F 2, C 4H 2F 6, C 4H 3F 7, C 5F 10, C 5HF 7, or a combination thereof; · further comprising adding an additive to C 2 H 2 F 2, wherein the additive is selected from H 2, SF 6, NF 3, NH 3, Cl 2, BCl 3, BF 3, Br 2, F 2, FNO, FNO 3, HBr, HCl, HI, IF 5, IF 7, or HF; further comprising adding a coreactant to C2H2F2; The co-reactant is an inert gas selected from the group consisting of Ar, Kr, Xe, Ne, N2, He, or a combination thereof; The co-reactant is selected from N2, Ar or a combination of the two, the combination having any ratio of each ranging from 0-100%; The co-reactant is selected from N2, Ar or a combination of both; A combination of N2 and Ar having a ratio of each ranging from 0-100%; · Further include: The coreactant N2 is added to C2H2F2; further comprising adding a coreactant Ar to C2H2F2; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 75-38-7; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 1630-78-0; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 1630-77-9; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 1691-13-0; The substrate temperature range is -20°C to 300°C; The substrate temperature range is -20°C to -196°C; The pressure in the chamber is between about 0.1 mTorr and about 1000 Torr; The pressure in the chamber is between about 1 mTorr and about 10 Torr; The pressure in the chamber is between about 10 mTorr and about 1 Torr; The pressure in the chamber ranges from 1 mTorr to hundreds of mTorr; The pressure in the chamber is maintained between 15 and 30 mTorr; The one or more dielectric films are SiO2 and SiOCH films; CO₂ equivalent emissions from the reaction chamber are at least 10% lower than CO₂ equivalent emissions using CF₄ as the etching gas; and The CO₂ equivalent emissions from the reaction chamber are not less than 10% lower than the CO₂ equivalent emissions when CF₄ is used as the etching gas.

[0021] An etching method for forming a structure with lower CO2 equivalent emissions 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 is disclosed, the method comprising: Mounting the substrate in a reaction chamber; The etching gas containing C 2H 2F 2 is introduced into the reaction chamber; converting the etching gas into plasma; and allowing 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 the reaction chamber are at least 10% lower than the CO2 equivalent emissions when CF4 is used as the etching gas. The disclosed etching method may include one or more of the following features: · Further include: 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, C4F10, C5F8, C6F6, C7F14, C7F16, or C8F16, wherein the one or more hydrofluorocarbon etching gases are C1-C8 hydrofluorocarbon CxFyHz molecules, wherein x, y and z are integers, 1 ≤ x ≤ 8, and the molecules are selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H 2F 6, C 3H 4F 2, C 4H 2F 6, C 4H 3F 7, C 5F 10, C 5HF 7, or a combination thereof; · further comprising adding an additive to C 2 H 2 F 2, wherein the additive is selected from H 2, SF 6, NF 3, NH 3, Cl 2, BCl 3, BF 3, Br 2, F 2, FNO, FNO 3, HBr, HCl, HI, IF 5, IF 7, or HF; further comprising adding a coreactant to C2H2F2; The co-reactant is an inert gas selected from the group consisting of Ar, Kr, Xe, Ne, N2, He, or a combination thereof; The co-reactant is selected from N2, Ar or a combination of the two, the combination having any ratio of each ranging from 0-100%; The co-reactant is selected from N2, Ar or a combination of both; A combination of N2 and Ar having a ratio of each ranging from 0-100%; The method further comprises adding a co-reactant, N₂, to the C₂H₂F₂; further comprising adding a coreactant Ar to C2H2F2; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 75-38-7; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 1630-78-0; C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 1630-77-9; C2H2F2 is an isomer of C2H2F2 with CAS number: 1691-13-0; and The substrate temperature range is -20°C to 300°C.

[0022] An etching method for forming a structure by selectively etching one or more dielectric films using a patterned mask layer deposited on top of the one or more dielectric films in a substrate is disclosed, the method comprising: Mounting the substrate in a reaction chamber; The etching composition comprising a gas mixture of C 2H 2F 2 and an inert gas is introduced into the reaction chamber; converting the etching composition into a plasma; and allowing 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. The disclosed etching method may include one or more of the following features: 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 the two with any ratio ranging from 0-100%; The inert gas is selected from N2, Ar or a combination of the two; A combination of N2 and Ar having a ratio of each ranging from 0-100%; · The inert gas system is N2; · the inert gas system Ar; and C 2H 2F 2 is an isomer of C 2H 2F 2 with CAS number: 75-38-7. [Symbols and nomenclature]

[0023] The following detailed description and claims utilize a number of abbreviations, symbols, and terms that are commonly known in the art and include:

[0024] As used herein, the indefinite article "a" or "an" means one or more.

[0025] As used herein, "about" or "around" or "approximately" in the text or claims means ±10% of the stated value.

[0026] As used herein, "room temperature" in the text or claims means about 20°C to about 25°C.

[0027] The term "substrate" refers to one or more materials on which a process is performed. A substrate may refer to a wafer having one or more materials on which a process is performed. The substrate may be any suitable wafer used in semiconductor, photovoltaic, flat panel, or LCD-TFT device manufacturing. The substrate may also have one or more layers of different materials deposited thereon from previous manufacturing steps. For example, a wafer may include a silicon layer (including but not limited to crystalline, amorphous, porous, etc.), a silicon-containing layer (including but not limited to SiO2, SiN, SiON, SiCOH, etc.), a metal or metal-containing layer (including but not limited to copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.), or a combination thereof. Furthermore, the substrate may be planar or patterned. The substrate may be an organic patterned carbon iodide film. The substrate may include an oxide layer (e.g., ZrO₂-based materials, HfO₂-based materials, TiO₂-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.) used as a dielectric material in field-effect transistor (FET) applications such as FinFET, MOFSET, GAAFET (Gate All Around FET), ribbon FET, nanosheet, fork-sheet FET, complementary FET (CFET), MEMS, 3D NAND, MIM, DRAM, or FeRam devices, or a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode. The substrate may include alternating layers of oxide (e.g., SiO) and nitride (e.g., SiN). Those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a thickness of a material laid or spread on a surface, and that the surface may be in the form of trenches or lines. Throughout this specification and claims, the wafer and any associated layers thereon are referred to as the substrate. The substrate may be any solid having functional groups on its surface that tend to react with the reactive heads of the self-assembled monolayer (SAM), and may include, but is not limited to, a 3D object or a powder.

[0028] 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 of films having a topographical feature or pattern created in a step prior to etching, and forming a patterned topmost film for pattern etching.

[0029] As used herein, the term "processing" includes patterning, exposing, developing, etching, depositing, cleaning, and / or removal of by-products, as required to form the described structures.

[0030] The term "deposit" or "deposition" refers to a series of processes in which a material at the atomic or molecular level is deposited as a thin layer from a gaseous (vapor) state to a solid state onto a wafer surface or substrate. The process involves chemical reactions that occur after generating a plasma of reactive gases or after activating the reactive gases 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 etch chambers include, but are not limited to, the Lam Research Dual CCP reactive ion etcher dielectric etch product line sold under the trademarks Flex™, Tokyo Electron Tactras™, or Episode™UL. The non-plasma exposure step can be performed in a separate chamber from the plasma exposure step. []

[0031] The term "aspect ratio" refers to the ratio of the height of a trench (or hole) to the width of the trench (or the diameter of the hole).

[0032] 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 material, and that a layer may refer to both a film and a material. Furthermore, those skilled in the art will recognize that the terms "film," "layer," or "material" as used herein refer to a thickness of a material applied or spread over a surface, and that the surface can range from as large as an entire wafer to as small as a trench or line.

[0033] It should be noted that, herein, the terms “aperture,” “via,” “hole,” “trench,” and “structure” may be used interchangeably to refer to an opening formed in a semiconductor structure.

[0034] As used herein, the abbreviation "NAND" refers to a "Negative AND" or "Not AND" gate; the abbreviation "2D" refers to a 2-dimensional gate structure on a planar substrate; and the abbreviation "3D" refers to a 3-dimensional or vertical gate structure in which gate structures are stacked in a vertical direction.

[0035] It should be noted that, herein, the terms "etching gas" and "etchant" are used interchangeably when the etching gas is in a gaseous state at room temperature and ambient pressure. It should be understood that the etching gas may correspond to or be associated with the etchant, and the etchant may refer to the etching gas.

[0036] The terms "dope" and "doping" are used interchangeably to refer to processes that incorporate one or more elements into a film by various methods that can chemically or physically incorporate the element, as well as processes that intentionally incorporate atoms of different elements into a film composition. Doping with one or more elements can be interstitial or substitutional within a film.

[0037] Standard abbreviations for the elements of the Periodic Table are used herein. It should be understood that elements may be referred to by these abbreviations (e.g., Si refers to silicon, N refers to nitrogen, O refers to oxygen, C refers to carbon, H refers to hydrogen, F refers to fluorine, etc.).

[0038] Unique CAS Registry Numbers ("CAS") assigned by the Chemical Abstracts Service are provided to identify specific molecules disclosed.

[0039] As used herein, the term "hydrofluorocarbon" refers to a saturated or unsaturated functional group containing only carbon, fluorine, and hydrogen atoms.

[0040] As used herein, the term "fluorocarbon" refers to a saturated or unsaturated functional group containing only fluorine and hydrogen atoms.

[0041] As used herein, the term "GWP" refers to Global Warming Potential, typically on a 100-year time scale and comparing the Global Warming Potential to CO2.

[0042] As used herein, “CO 2 emissions” or “CO 2 equivalent emissions” refers to the comparison between the GWP of C 2 H 2 F 2 and gases like CF 4 and CHF 3 (commonly used fluorocarbon and hydrofluorocarbon etching gases) and emissions from plasma etching processes.

[0043] Ranges may be expressed herein as from about one particular value and / or to about another particular value. When such a range is expressed, it should be understood that another embodiment is from the one particular value and / or to the other particular value, along with all combinations within the recited range. Any and all ranges recited herein include their endpoints (i.e., x = 1 to 4, or x is 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.

[0044] References herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. This also applies to the term "implementation."

[0045] As used herein, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete manner.

[0046] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless specified otherwise or clear from the context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied in any of the foregoing instances. Furthermore, the articles "a" and "an," as used in this application and the appended claims, should generally be construed to mean "one or more," unless specified otherwise or clear from the context to direct to a singular form.

[0047] The term "comprising" in a claim is an open transition term, meaning that the subsequently identified claim elements are a non-exclusive list (i.e., anything else may additionally be included and remain within the scope of "comprising"). "Comprising" is defined herein to necessarily encompass the more restrictive transition terms "consisting essentially of" and "consisting of"; thus, "comprising" can be replaced by "consisting essentially of" or "consisting of" and remain within the clearly defined scope of "comprising."

[0048] The term "providing" is defined in the claims as meaning to supply, furnish, make available, or prepare something. A step may instead be performed by any actor in the absence of explicit language in the claims. Simple diagram description

[0049] For a further understanding of the nature and purpose of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which like elements are given the same or similar reference numerals, and in which: [[] [picture] [1]] is the FTIR spectrum of the emissions from the CHF 3 plasma etching process for etching SiO 2 films; [[] [picture] [2]] is the FTIR spectrum of the emissions from the C 2H 2F 2 plasma etching process for etching SiO 2 films; [[] [picture] [3]] is the etching rate of two etching gases (C2H2F2 and CHF3) in the etching process of SiO2 film at high and low plasma source power; [[] [picture] [4]] is the SiO2 etch rate as a function of N2 or O2 addition for C2H2F2 / Ar etching; [[] [picture] [5]] Low-k dielectric etch rate as a function of N 2 or O 2 addition for C 2H 2F 2 / Ar etch; [[] [picture] [6]] is a comparison of the etching rates of CF 4, CHF 3, CF 3I and C 2H 2F 2 for polysilicon film, SiO 2 film, SiN film and SOC film; [[] [picture] [7]] compares the selectivity of CF 4, CHF 3, CF 3I and C 2H 2F 2 for polysilicon film, SiO 2 film, SiN film and SOC film; [[] [picture] [8]] is the mass spectrum of pure CHF 3; [[] [picture] [9]] is the mass spectrum of pure C 2H 2F 2; and [[] [picture]

[10] ] is the mass spectrum of pure CF4. Implementation Method

[0050] Disclosed is a method for etching dielectric materials or layers and / or Si-containing materials or layers using a hydrofluorocarbon etching gas, C2H2F2 plasma, to form patterned structures for semiconductor wafer fabrication, such as for back-end-of-line (BEOL) processing of logic devices or interconnects (trench etching and via etching), and high-k etching (such as transistor and gate patterning, slit 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.

[0051] Conventional fluorocarbon and hydrofluorocarbon gases can have high global warming potentials (GWPs), and when exposed to plasma, they decompose and can form substances that also have high GWPs. These high-GWP substances are then emitted. In some cases, even when byproducts are scrubbed, the scrubbing process may be incomplete because not 100% of the fluorinated substances are converted to CO₂. Furthermore, plasma and thermal scrubbers can even produce high-GWP byproducts from these reactions.

[0052] Compared to commonly used hydrofluorocarbon etching gases, the disclosed plasma etching method using C₂H₂F₂ and an inert co-reactant (e.g., N₂) achieves at least a 10% reduction 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 CO₂ equivalent emissions from 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.

[0053] like [surface] As shown in [1], C2H2F2 is particularly attractive due to its very low GWP (< 1), while other traditional fluorocarbon and hydrofluorocarbon etching gases have very high GWPs, such as CH2F2 with a GWP of 677.

[0054] C 2H 2F 2 has the following [surface] [2] lists the four main isomers. Here, the preferred C 2 H 2 F 2 molecule is CAS No. 75-38-7. [[] [surface] [2] name Mode structure CAS number boiling point 1,1-Difluoroethylene C 2H 2F 2 75-38-7 -83°C (E)-1,2-Difluoroethylene C 2H 2F 2 1630-78-0 -86°C (Z)-1,2-Difluoroethylene C 2H 2F 2 1630-77-9 -36°C 1,2-Difluoroethylene C 2H 2F 2 1691-13-0 -28°C

[0055] C2H2F2 is supplied in cylinders in a variety of fills, pressures, and sizes. Preferably, the C2H2F2 in the cylinders has a low moisture content of <40 ppm, preferably <10 ppm. C2H2F2 can be purified using distillation, adsorption on molecular sieves, or other conventional methods to remove key impurities such as other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFCs), airborne impurities such as N2, O2, CO2, water (H2O), HF, and other hydrocarbons such as CH4. Some impurities can form azeotropes, so additional purification methods may be required to chemically separate them.

[0056] The disclosed plasma etching method includes exposing a substrate to an etching gas of C 2 H 2 F 2 and / or one of its isomers, preferably C 2 H 2 F 2 (CAS No.: 75-38-7), in a reaction chamber during a plasma etching process and / or during a chamber conditioning process.

[0057] The disclosed plasma etching method for forming holes or structures by selectively etching one or more dielectric films using a patterned mask layer deposited on top of the one or more dielectric films in a substrate comprises: Mounting the substrate in a reaction chamber; The etching gas containing C 2H 2F 2 is introduced into the reaction chamber; converting the etching gas into plasma; and An etching reaction is allowed to proceed 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.

[0058] The reaction chamber can be any enclosure or chamber within an apparatus in which an etching process is performed, such as, but not limited to, reactive ion etching (RIE), CCP with single or multiple frequency RF sources, inductively coupled plasma (ICP), microwave plasma reactor, or other types of etching systems capable of performing plasma processing (i.e., selectively removing a portion of a dielectric film or generating reactive species or deposited films).

[0059] The reaction chamber is equipped with a parallel-plate electrode plasma generator, in which a high-frequency electromagnetic field of 60 MHz is applied to the upper electrode and a 2 MHz electromagnetic field is applied to the lower electrode, while the gap between the electrodes is maintained in the range of 10 to 35 mm. This combination of electric fields allows the application of a power in the range of 0-2000 W to the upper electrode and a power in the range of 1500-7000 W 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 from hundreds to several thousand kW of source power.

[0060] The temperature and pressure within the reaction chamber are maintained at conditions suitable for the reaction of the process film with the activated etching gas C2H2F2. For example, depending on the etching parameters, 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, and 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. When the etching gas mixture is introduced, the pressure in the etching chamber is maintained between 15 and 30 mTorr during the plasma etching process. Similarly, the substrate temperature or reaction chamber temperature in 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 in the reaction chamber may range from 20°C to 200°C.

[0061] Additional one or more hydrofluorocarbon or fluorocarbon etching gases may be added to C 2H 2F 2. The additional one or more fluorocarbon etching gases may be selected from CF 4, C 2F 6, C 3F 8, C 4F 6, C 4F 8, C 2F 4, C 3F 6, C 4F 10, C 5F 8, or C 6F 6, C 7F 14, C 7F 16, or C 8F 16. The additional one or more hydrofluorocarbon etching gases can be selected from C1-C6 hydrofluorocarbon CxFyHz molecules (x, y and z are integers, 1 ≤ x ≤ 8), which are selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F10, C5HF7, or combinations thereof.

[0062] refer to [surface] [1], some hydrofluorocarbons or fluorocarbons have high GWP compared to C 2H 2F 2. In order to improve etching performance and etching quality, one or more hydrofluorocarbon or fluorocarbon etching gases can be added to C 2H 2F 2 to slightly adjust the etching performance. When a small amount of hydrofluorocarbons or fluorocarbons with high GWP values is added, the total CO 2 equivalent emissions from the reaction chamber may not have much impact considering the improved etching performance. For example, when less than 10% of one or more hydrofluorocarbon or fluorocarbon etching gases relative to C 2H 2F 2 are added to C 2H 2F 2, the CO 2 equivalent emissions from the reaction chamber may not change significantly compared to the significantly improved etching performance. In practice, it may be necessary to balance the reduction of CO 2 equivalent emissions and high etching performance.

[0063] Other gases (such as additives) can be added to C 2H 2F 2. The additives include H 2, SF 6, NF 3, NH 3, Cl 2, BCl 3, BF 3, Br 2, F 2, FNO, FNO 3, HBr, HCl, HI, IF 5, IF 7, or HF.

[0064] A co-reactant (e.g., an inert gas) may also be added to the etching gas C2H2F2. The inert gas may be selected from He, Ar, Kr, Xe, Ne, N2, or a combination thereof. In some embodiments, N2, Ar, or a combination thereof may be added to C2H2F2. The combination of N2 and Ar may have any ratio ranging from 0-100%. The flow rates of C2H2F2, N2, and Ar may range from 1 sccm to 10 slm, preferably greater than 10 sccm and less than 1 slm. Different C2H2F2 / N2 / Ar flow rate ratios may be used. Here, N2 and / or Ar may be replaced by other inert gases (e.g., Kr, Xe, Ne, He, or a combination thereof). In some embodiments, N2 may be added to C2H2F2. In some embodiments, Ar may be added to C2H2F2.

[0065] Etching processes can be continuous or cyclic. For cyclic etching, such as atomic layer etching (ALE), the etchant in the plasma etch step is Ar and the precursor in the deposition step is C₂H₂F₂. During the deposition step, the source plasma power is on and the bias power is off. During the etch step, both the source power and the bias power are on, resulting in a mixture of gaseous byproducts exiting the plasma etch chamber that has a lower global warming potential (GWP) than processes using traditional fluorocarbon etching gases such as CF₄ or CHF₃.

[0066] The C2H2F2 etch step can be performed independently on the exposed dielectric substrate, or it can be one step in a longer overall etch protocol that includes a mask open step, a lower layer penetration etch step, or a post-etch clean step. For the C2H2F2 etch process, various advanced process control mechanisms can be employed, including but not limited to wafer-sequential etch time or flow rate correction to account for cross-batch effects, preventive maintenance (PM) cycle-based time or flow rate correction to account for cross-PM effects, pre-batch or mid-batch chamber conditioning to account for cross-batch effects, post-wafer batch chamber cleaning to reset chamber conditions, OES-based endpoint for landed etch, and feed-forward or feedback-based time or flow rate correction to control the depth or CD of etched features.

[0067] The substrate contains a dielectric material or film, such as SiO₂ or SiOCH₂. An example is a dielectric film layer used in interconnect metal layers. The dielectric film includes a layer of SiO₂ or SiOCH₂. The dielectric film or material includes one or more Si₁₂O₄H₂₀C₀N₂ layers, where a > 0, b, c, d, and e ≥ 0, and is selected from silicon oxide, silicon nitride, crystalline Si, polycrystalline silicon, polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, and SiON.

[0068] Materials to be etched include silicon-containing films such as SiO2, carbon-containing SiO2 such as low-k dielectric SiOCH (formed by PECVD, spin-on 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-on 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 SiO2 or SiOCH low-k dielectric material.

[0069] Here, SiO films may include, but are not limited to, films containing Si, O, C, B, N, or H deposited using CVD (with or without plasma), spin-on deposition, or other methods. The silicon-containing film may also be a silicon oxide-based dielectric material, such as an organic-based or silicon oxide-based low-k dielectric material, such as Applied Materials, Inc.'s Black Diamond I, II, or III materials (having the formula SiOCH). The silicon-containing film may also include Si aO bN c, where a, b, and c range from 0.1 to 6. The silicon-containing film may also include dopants such as B, C, P, As, and / or Ge. The film may be porous, having a wide range of pore sizes.

[0070] On top of the dielectric film or material is a mask layer or mask material. The mask material can be a layer of amorphous carbon, doped amorphous carbon, SOC (spin-on carbon), Si, SiN, Al, AlO, Ti, TiO, other metal and metal oxide masks, or other nitrides (such as TiN) with or without dopants.

[0071] C 2H 2F 2 is supplied in gas cylinders at a variety of filling quantities, pressures and specifications. Preferably, the material has a low moisture content of < 40 ppm and preferably < 10 ppm. C 2H 2F 2 can be purified using distillation, adsorption using molecular sieves, or other commonly known methods in the art to remove key impurities, such as chlorine substances or organochlorides, other fluorocarbons, hydrofluorocarbons, chlorofluorocarbons (CFCs), impurities from air (N Some impurities can form azeotropes, therefore, it may be necessary to use other purification methods using chemical means to separate them. The main application of the disclosed plasma etching methods is to selectively plasma etching silicon-containing layers such as SiO 2 equivalents) GWP emissions. C 2H 2F 2 not only has a much lower GWP than standard or commonly used fluorochemical etching gas, it also produces lower GWP emissions from the etching process than those using standard fluorochemical etching gas such as CF 4 as etching gas. Such etching processes are commonly used in back-end processes of dielectric etching processes to form grooves, through holes, and spacers to manufacture logic devices. C 2H 2F 2 and N 2 or C 2H 2F 2 , N 2 and Ar can also be used to manufacture storage devices and a wide variety of other semiconductor devices.

[0072] The disclosed plasma etching method uses C 2H 2F 2 as the etching gas to etch the dielectric film thereby creating holes in the silicon-containing film, such as channel holes, gate grooves, stepped contacts, capacitor holes, contact holes, contact etching parts, slit etching parts, self-alignment contacts, self-aligning through holes, and super-through holes. The size range of the etched structure can be a patterned feature of nm to cm with a vertical depth of nm to mm. Applications can range from pattern transfer (e.g., three-layer etching, pitch doubling, etching stop penetration), dielectric etching (grooves, vias, junctions) to small features (gate, source, drawer patterning) to large features (silicon perforations (through silicon via), storage channels). The structure may be, but is not limited to, grooves, holes, plugs, etc.

[0073] 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, duration of the process), process gas mixture, the combination and ratio of gases in the process gas mixture, gas flow rates, the workpiece, and the plasma etching chamber itself can be varied for each process and during the process.

[0074] In summary, the disclosed plasma etching method provides enhanced control over the deposition profile of polymer films and the etching of dielectric materials with high etch rates and selectivity using C2H2F2. Furthermore, C2H2F2 has a lower global warming potential (GWP) than commonly used gases (e.g., CF4, CHF3, C4F8, CH2F2), enabling a more eco-friendly process. For example, CO2-equivalent emissions from the reaction chamber using C2H2F2 are at least 10% lower than when using CF4 as the etching gas. [] [Example] []

[0075] A more detailed description of the disclosed method is provided below by way of example. However, the disclosed method is not limited in any way to the examples presented, and the process conditions, process gas mixture, combination and ratio of gases in the gas mixture, workpiece, and plasma etching chamber itself may vary.

[0076] In the following examples, the primary plasma etching source may be CCP plasma, but other sources such as ICP, microwave, and ECR 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 gas may be added to slightly adjust the etching performance. Additional inert gases such as Kr, Xe, Ne, and Ne, as well as hydrogen source gases such as H2, and hydrocarbons may be added. Mask materials may include TiN or other metal nitride materials, SiN, Si, carbon materials, and the like. [Example] [1] FTIR of emissions from a CHF3 plasma etching process

[0077] The FTIR of the emission from the CHF 3 plasma etching process for etching SiO 2 films was measured and the FTIR spectrum is shown in [picture] [1] The process conditions are as follows. The temperature is 20°C / 150°C ESC / UEL (electrostatic chuck or wafer temperature / upper electrode); the plasma source power is 500 W source plus 150 W bias; the pressure is 20 mTorr; and the CHF3 / N2 flow rate is 20 / 80 sccm for 60 s. As shown, the main emission species are SiF4, CHF3, CF4, CO, CO2, and HF. [Example] [2] FTIR of emissions from a C 2H 2F 2 plasma etching process []

[0078] The FTIR of the emission from the C 2 H 2 F 2 plasma etching process for etching SiO 2 films was measured and the FTIR spectrum is shown in [picture] [2]. The process conditions are as follows. The temperature is 20°C / 150°C ESC / UEL (electrostatic chuck or wafer temperature / upper electrode); the plasma source power is 500 W source plus 150 W bias; the pressure is 20 mTorr; and the flow rate of C 2H 2F 2 / N 2 is 20 / 80 sccm for 60 s. As shown, the main emission substances are SiF 4, CHF 3, CF 4, CO, CO 2, and HF. [picture] [1] [picture] [2] When compared, it can be seen that the CHF 3 peak and CF 4 peak of the C 2 H 2 F 2 spectrum are much smaller than those of CHF 3, which indicates that the emission species for C 2 H 2 F 2 has a much lower GWP. [Example] [3] C 2H 2F 2 and CHF 3 plasma etching process []

[0079] Two different source powers of 2000 W and 500 W were used in a 300 mm dielectric CCP etch tool at 100 W bias power at pressures of 25 mTorr and 5 mTorr. Two etching gases (C 2 H 2 F 2 and CHF 3) were evaluated in an etch process for etching SiO 2 films. The results are shown in [picture] [3]. The etching composition comprises C 2H 2F 2, Ar and N 2, or CHF 3, Ar and N 2, respectively. The flow rate of C 2H 2F 2 or CHF 3 is 15 sccm. The flow rates of Ar and N 2 are each 52.5 sccm. The wafer temperature is 20°C. The high pressure is 25 mTorr and the low pressure is 5 mTorr. As shown, the selectivity of C 2H 2F 2 for etching SiO 2 relative to the TiN mask material by using N 2 and Ar is higher than the selectivity of CHF 3 by using N 2 and Ar. O 2 is not used in the etching process. Conventionally, O 2 is used as a co-reactant in the plasma etching process to control polymerization. However, based on [picture] The results in [3] found that N 2 effectively controlled the polymerization with C 2H 2F 2. For each etching composition, good selectivity with respect to the mask material (like TiN) was achieved, and thus, polymerization was controlled in the absence of O 2 by adding N 2 and Ar. For CHF 3, the selectivity for etching SiO 2 with respect to TiN was 46 at a low source power of 500 W, and for C 2H 2F 2, the selectivity was 70. Thus, much higher selectivity was observed using C 2H 2F 2 instead of CHF 3, where the selectivity was increased by 52%. For CHF 3, at a high source power of 2000 W, the selectivity for etching SiO 2 with respect to TiN was 28, and for C 2H 2F 2, the selectivity was 44, an increase of 57%, as shown in FIG. [surface] As shown in [3]. As shown, C2H2F2 / N2 / Ar maintains higher selectivity than the equivalent composition using CHF3 at both low and high source powers. [[] [surface] [3]] chemical composition SiO 2 : TiN selectivity at low power SiO 2:TiN selectivity at high power CHF 3 / N 2 / Ar 46 28 C 2H 2F 2 / N 2 / Ar 70 44 [Example] [4] [:] C 2 H 2 F 2 etching with N 2 or O 2 []

[0080] The SiO 2 etch rate was evaluated using C 2H 2F 2 as a function of O 2 and N 2 under different plasma and flow conditions. The conditions are as follows. The plasma RF source power was varied from 400 W to 800 W, and the bias power was 150 W. The pressure was 10 mTorr, and the flow rate of C 2H 2F 2 was 15 sccm. The flow rates of O 2, Ar, and N 2 were adjusted. The wafer temperature was 20°C. At a C 2H 2F 2 flow rate of 15 sccm, 10 sccm of O 2 was required to achieve an etch rate of approximately 35 nm / min. However, in the absence of O 2 and with the addition of 40 sccm of N 2, the SiO 2 etch rate was approximately 55 nm / min. Therefore, by adding N 2 instead of O 2, the SiO 2 etch rate is significantly higher in the case of C 2H 2F 2, as shown in FIG. [picture] As shown in [4]. [picture] [5] is the low-k etch rate as a function of O2 flow rate. The etch rate with added O2 is similar to that with N2 up to a flow rate of 10 sccm, however at higher flow rates the etch rate is faster with added O2 than with N2. [Example] [5] [:] C 2H 2F 2 etching compared to CF 4, CHF 3 and CF 3I []

[0081] The etch rates and selectivities of four different fluorocarbon etching gases (C 2 H 2 F 2, CF 4, CHF 3, and CF 3I) were measured in a 300 mm CCP plasma etch tool under similar etching conditions. The comparison includes two very high GWP gases (CF 4 and CHF 3) and two lower GWP gases (CF 3I and C 2 H 2 F 2). The results are shown in [picture] [6] and [picture] [7]. The process conditions are as follows. The temperature is 20°C / 150°C ESC / UEL; the plasma source power is 500 W source + 150 W bias; the pressure is 20 mTorr; the flow rate of the etching gas is 20 sccm for 60 s; and the flow rate of N2 is 80 sccm N2 for 60 s. Under these conditions, C2H2F2 has the highest SiO2 etching rate and the highest selectivity for etching SiO2 relative to SOC (spin-on carbon mask material). Therefore, the lower GWP gas C2H2F2 provides improved etching performance compared to both the lower GWP gas and the higher GWP gas. [Example] [6] [:] Emissions from CF4, CHF3, and C2H2F2 etching processes []

[0082] Emissions from CF₄, CHF₃, and C₂H₂F₂ etch processes for SiO₂ films were measured on a 300 mm plasma etch tool. Experimental conditions were identical for each gas: temperature was 20°C / 150°C ESC / UEL; plasma source power was 500 W source + 150 W bias; pressure was 20 mTorr, and flow rates were 20 sccm for the etch gas and 80 sccm for N₂ for 60 s. Emissions were quantified for processes with equivalent etch rates between C₂H₂F₂, CF₄, and CHF₃. The CHF3 process was found to have CO2eq (CO2 equivalent) emissions of 1.87E-04 g / wafer, the CF4 process had CO2eq emissions of 4.61E-04, and the C2H2F2 process had CO2eq emissions of 3.88E-05 g / wafer. CO2eq emissions from C2H2F2 were only 20% of those from the equivalent CHF3 process (an 80% reduction) and 8% of those from CF4 (a 92% reduction). Therefore, C2H2F2 not only offers improved SiO2 etch selectivity relative to TiN and SOC, but also significantly reduces CO2eq emissions. This demonstrates that C2H2F2 has both a lower GWP and lower-GWP emissions compared to CHF3 and / or CF4. [Example] [7] [:] Mass spectra of CF4, CHF3, and C2H2F2 etching []

[0083] The mass spectra of each of the gases CF 4, CHF 3 and C 2H 2F 2 were compared using a Hiden mass spectrometer as a function of electron volts (eV). The spectrum of pure CHF 3 was evaluated and is shown in [picture] [8]. The mass spectrum of C 2H 2F 2 is shown in [picture] [9]. The mass spectrum of CF 4 is shown in [picture]

[10] . As shown, the mass spectra of each molecule are very different, with the main species of C2H2F2 being C2H2F species (C / F ratio of 2); the main species of CHF3 being 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 can help improve selectivity. On the other hand, CF4, as expected, produces the main CF3 species, which is an etching species with very little polymerization protection properties. [Example] [8] [:] CH2F2, C4F8, CHF3, and C2H2F2 deposition []

[0084] The deposition rates of different fluorocarbon gases were compared by flowing the gases at 15 sccm into a 200 mm CCP plasma etch tool along with Ar at 250 sccm and a plasma source power of 750 W and no bias power. No O2 was flowed into the etch tool. [surface] As shown in [4], C2H2F2 provides an increased polymer deposition rate, which is beneficial for sidewall protection in patterning processes. Based on the data shown in the previous example, it was also shown that the addition of N2 to control the polymerization of C2H2F2 is very effective in overcoming the increased polymer deposition rate compared to CHF3. [[] [surface] [4]] gas Deposition rate (nm / min) CHF 3 40 CH2F2 65 C 4F 8 twenty three C 2H 2F 2 80 [Example] [9] [:] Etch rates of SiO2, low-k, and TiN using C2H2F2

[0085] A 300 mm CCP plasma etch tool was used to evaluate the etch rates of SiO2, low-k, and TiN at different temperatures, pressures, plasma powers, and Ar / N2 flow ratios. [surface] [5] shows the conditions and results for three experiments. As shown, low-k etching is slightly faster than SiO2 etching, resulting in a higher selectivity for etching low-k relative to TiN mask material. Therefore, SiO2 is a good representative film for various commercially available low-k films. Moreover, the etch rate can be highly dependent on temperature and plasma power. [[] [surface] [5]] experiment Temperature (°C) pressure (mitorr) Source power (W) Bias power (W) C 2H 2F 2 N 2 Ar Etching rate SiO 2 (nm / min) Etch rate low k (nm / min) Etching rate TiN (nm / min) SiO 2: TiN selectivity (nm / min) Low-k: TiN selectivity (nm / min) 1 20 5 2000 500 15 105 0 93 161 9 10 18 2 60 5 500 500 15 52.5 52.5 57 105 10 6 11 3 20 25 2000 500 15 52.5 52.5 104 201 10 11 20

[0086] It should be understood that many additional changes in the details, materials, steps, and arrangements of parts described herein and illustrated to explain the essence of the invention may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims. Therefore, the present invention is not intended to be limited to the specific embodiments shown in the examples and / or drawings above.

[0087] Although embodiments of the present invention have been shown and described, modifications thereof may be made by those skilled in the art without departing from the spirit or teachings of the invention. The embodiments described herein are intended to be illustrative only and not restrictive. Many variations and modifications of the compositions and methods are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is limited solely by the claims that follow, which shall include all equivalents of the subject matter of the claims.

[0088] none

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; And allows for an etching 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, wherein C2H2F2 is an isomer of C2H2F2 having CAS number: 75-38-7, CAS number: 1630-78-0, CAS number: 1630-77-9 or CAS number: 1691-13-0.

2. The method as described in claim 1, further comprising adding one or more hydrofluorocarbon or fluorocarbon etching gases to C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F10, C5F8, or C6F6, C7F14, C7F16, or C8F16, wherein the one or more hydrofluorocarbon etching gas system comprises C1-C8 hydrofluorocarbon CxFyHz molecules, where x, y, and z are integers, 1 ≤ x ≤ 0.

8. The molecule is selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F10, C5HF7, or combinations thereof.

3. The method as described in claim 1, further comprising 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.

4. The method as described in claim 1, further comprising adding a co-reactant to C2H2F2, the co-reactant being an inert gas selected from the group consisting of Ar, Kr, Xe, Ne, N2, He, or a combination thereof.

5. The method as described in claim 1, further comprising adding co-reactant N2 to C2H2F2.

6. The method as described in any one of claims 1 to 5, wherein, The dielectric film system consists of SiO2 film and SiCOH film.

7. The method as described in 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.

8. An etching method for forming a structure with lower 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 mounted in the reaction chamber; an etching gas containing C2H2F2 is introduced into the reaction chamber; The etching gas is converted into plasma; And 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, wherein the CO2 equivalent emissions from the reaction chamber are at least 10% lower than the CO2 equivalent emissions when using CF4 as the etching gas.

9. The method as described in claim 8, further comprising adding one or more hydrofluorocarbon or fluorocarbon etching gases to the etching gas C2H2F2, wherein the one or more fluorocarbon etching gases are selected from CF4, C2F6, C3F8, C4F6, C4F8, C2F4, C3F6, C4F10, C5F8, C6F6, C7F14, C7F16, or C8F16, wherein the one or more hydrofluorocarbon etching gas system comprises C1-C8 hydrofluorocarbon CxFyHz molecules, where x, y, and z are integers, 1 ≤ x ≤ 0.

8. The molecule is selected from CHF3, CH2F2, CH3F, C2HF5, C2H5F, C2H5F, C3H7F, C3H2F6, C3H2F4, C3H2F6, C3H4F2, C4H2F6, C4H3F7, C5F10, C5HF7, or combinations thereof.

10. The method as described in claim 8, further comprising 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.

11. The method as described in claim 8, further comprising adding a co-reactant to C2H2F2, the co-reactant being an inert gas selected from the group consisting of Ar, Kr, Xe, Ne, N2, He, or a combination thereof.

12. The method as described in any one of claims 8 to 11, wherein, C2H2F2 is an isomer of C2H2F2 with CAS number 75-38-7.

13. 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 comprising a gas mixture containing C2H2F2 and an inert gas is introduced into the reaction chamber; The etched composition 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, wherein the temperature range of the substrate is -20°C to 300°C, and wherein C2H2F2 is an isomer of C2H2F2 with CAS number: 75-38-7.

14. The method as described in claim 13, wherein, The inert gas is selected from Ar, Kr, Xe, Ne, N2, He or a combination thereof.

15. The method as described in claim 13, 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%.

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