High-conductive passivation layer and method for forming them during high-aspect-ratio plasma etching

Abstract

To provide a method for forming a high-aspect-ratio (HAR) structure during HAR etching processing to a substrate in a reaction chamber.SOLUTION: A method contains steps of: sequentially or simultaneously exposing a substrate to vapor of an etchant containing a hydrofluorocarbon or a fluorocarbon compound and an additive agent compound; providing a film to which the substrate is arranged thereon, and a patterned mask layer which is arranged onto the film; generating the hydrofluorocarbon or the fluorocarbon compound to be activated and the additive agent compound to be activated by activating a plasma; selectively etching the film from the patterned mask layer by progressing an etching reaction between a film that is not coated with the patterned mask layer and the activated hydrofluorocarbon or the fluorocarbon compound and the activated additive agent compound; and forming a high-aspect-ratio (HAR) patterned structure.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application No. 17 / 135,216, filed December 28, 2020, which is incorporated by reference in its entirety for all purposes.

[0002] A method is disclosed for forming a highly conductive sidewall passivation layer on the sidewalls using etching gases as additives by doping with Si, C, and / or iodine elements and / or introducing cyclic, aromatic, and heterocyclic chemical structures during high aspect ratio (HAR) plasma etching. [Background technology]

[0003] For over 50 years, Moore's Law has driven semiconductor manufacturers to continuously shrink device feature sizes to increase transistor / chip speed and capabilities while maintaining a cost advantage over competitors. This has created new challenges for manufacturing processes to successfully meet the demands of smaller and smaller feature sizes and dramatically increasing aspect ratios. For example, the manufacture of three-dimensional gate-stacked NAND flash memory (3D-NAND) requires the ability to etch small hole features in 90+ NAND layers with aspect ratios exceeding 40. Over one trillion holes will need to be etched in every wafer using ultra-high aspect ratio (HAR) etching.

[0004] Vertical isotropy of the etched features is achieved by ion transport during plasma sheath formation. In principle, positive and negative particles should follow the same trajectory in the hole, resulting in equalized charge at the bottom of the HAR hole. However, due to electron shading effects, charge can accumulate at the bottom of the HAR mask pattern, resulting in incomplete etching, bowing, twisting, and critical dimension (CD) variations between the top and bottom of the HAR stack. Therefore, many efforts have been and continue to be made in the industry to eliminate or minimize the sidewall charge build-up during HAR etching to improve the etch profile and CD control.

[0005] Contact hole distortion is known to be caused by asymmetric charging of the contact hole sidewall, which changes the local electric field in the contact hole and changes the direction of reactive ions in the contact hole (see Kim et al., J. Vac. Sci. Technol. A, Vol. 33, 021303-5 (2015) and Negishi et al, J. Vac. Sci. Technol. B, Vol. 35, 051205 (2017)). In HAR etching, ellipticity has been used to evaluate mask degradation. A high (close to 100%) ellipticity can help avoid twisting of HAR holes and reduce distortion of the etch profile.

[0006] Below are some examples of methods that have been used to tune the properties of the passivation layer during HAR etching, but the natural consequence is: 1) complex gas / chemical delivery setup to the process chamber; 2) poor uniformity of the passivation layer at the top and bottom of the HAR features; and 3) chamber cleaning issues - some metal-containing polymer builds up on the chamber walls and is difficult to completely remove.

[0007] Sandhu et al., US Patent Publication No. 20070049018, discloses a method for HAR contact etching substantially vertical contact holes in an oxide layer using a hard photoresist mask. The plasma etch gas is a fluorocarbon including one of CH2F2, C4F8; C3H3F5, C4F8; CHF3; C2F6; C2HF5, CH3F, or a combination thereof. The dopant molecule includes one of HI, CH3I, carbon, potassium, calcium, PF6, BF3, chloride, AsF6, or a combination thereof. The doped plasma etch gas etches substantially vertical contact holes through an oxide layer by doping the carbon chain polymer formed along the sidewalls of the contact holes during the etching process into a conductive state. The conductive state of the carbon chain polymer reduces charge buildup along the sidewalls, prevents twisting of the contact holes by bleeding off the charge, and ensures proper alignment with the landing regions of the active areas. The etch stops at the underlying substrate.

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

[0009] Nikhil et al., U.S. Pat. No. 9,543,158, discloses various methods, apparatus, and systems for forming recessed features in a dielectric material on a substrate. In some cases, a protective coating is deposited using plasma-assisted atomic layer deposition, modified plasma-assisted atomic layer deposition, or plasma-assisted chemical vapor deposition. The etching chemistry is a combination of fluorocarbons and oxygen, C4F6, C4F3, N2, CO, CF4, and O2. The protective layer is a ceramic-based material or an organic polymer. For boron-containing materials such as boron oxide (BxOy) and boron nitride (BxNy), reactants include, but are not limited to, triisopropyl borate ([(CH3)2CHO]3B), trimethylboron-d9 (B(CD3)3), and the like. Silicon oxide (Si x O y ) and silicon nitride (Si x N y For silicon-containing materials such as SiO 2 , the reactant may be, for example, a silane, a halosilane, or an aminosilane.

[0010] The HAR etch process has become a critical process for memory devices. Ion energy control by increasing the effective bias power of HAR features continues to advance. Significant efforts have been made to increase ion energy to overcome charge buildup at the etch front in HAR holes. Based on bias power trends over the past few years, the power required today would exceed 20 kW. As bias power increases, many challenges arise. Prevention of arcing, effective cooling, and power delivery systems are all critical to achieve high power capabilities. In addition, it becomes difficult to compensate for neutral flux as the aspect ratio increases, since neutral species can only move by diffusion through holes. Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, there is a need to achieve a highly conductive sidewall passivation layer while reducing the bias power. [Means for solving the problem]

[0012] A method for forming a high aspect ratio (HAR) structure on a substrate in a reaction chamber during a HAR etching process is disclosed, the method comprising: sequentially or simultaneously exposing a substrate having a film disposed thereon and a patterned mask layer disposed on the film to a vapor of an etchant comprising a hydrofluorocarbon or fluorocarbon compound and an additive compound; activating the plasma to produce an activated hydrofluorocarbon or fluorocarbon compound and an activated additive compound; and allowing an etching reaction to proceed between the film not covered by the patterned mask layer and the activated hydrofluorocarbon or fluorocarbon compound and the activated additive compound to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure; The disclosed methods may include one or more of the following aspects: further comprising the step of introducing an oxidant into the reaction chamber, the oxidant being selected from O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof; · The oxidant is O2; · The oxidant is O3; · The oxidant is CO; · Mixing the etching compound, the additive, and the oxygen-containing gas to form a mixture prior to introduction into the chamber; Introducing etching compounds and additives separately from the oxygen-containing gas; · Sequentially introducing an oxygen-containing gas and an iodine-containing etching compound; the oxygen-containing gas comprises from about 0.01% v / v to about 99.9% v / v of the total volume of the etching compound, the additive, and the oxygen-containing gas; the oxygen-containing gas comprises from about 0.01% v / v to about 10% v / v of the total volume of the etching compound, the additive, and the oxygen-containing gas; introducing an inert gas into the reaction chamber, the inert gas being selected from the group consisting of He, Ar, Xe, Kr, Ne and N2; · The inert gas is Ar; · The inert gas is Xe; · The inert gas is Kr; · Mixing the etching compound, additive, and inert gas to form a mixture prior to introduction into the chamber; Introducing etching compounds and additives separately from the inert gas; · Continuous introduction of inert gas and pulsed introduction of etching compounds and additives; the inert gas comprises from about 0.01% v / v to about 99.9% v / v of the total volume of the etching compound, additive, and inert gas vapor; The inert gas comprises about 90% v / v to about 99.9% v / v of the total volume of the etching compound, additive, and inert gas vapor; The substrate is a Si wafer; The substrate is a crystalline silicon layer; · Forming patterned structures; The patterned structure is a 3D NAND aperture; The patterned structures are contact holes; The patterned structures are 3D NAND contact holes; · The patterned structures are DRAM contacts; · The patterned structures are channel holes; The patterned structure is a 3D NAND channel hole; The patterned structure is a 3D NAND slit contact; · The aperture is a stepped contact; · The aperture is a self-aligning contact; · The aperture is a self-aligned via; · The aperture is a supervia; · Plasma-activated fluorocarbon compounds and activated additive compounds react with the film to form volatile by-products; · Volatile by-products are removed from the reaction chamber; A highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structures; the electrical conductivity of the highly conductive sidewall passivation layer formed using the activated hydrofluorocarbon or fluorocarbon compound and the activated additive compound is at least about 10% higher than the electrical conductivity of the highly conductive sidewall passivation layer formed using the activated hydrofluorocarbon or fluorocarbon compound without the addition of the activated additive compound; The hydrofluorocarbon or fluorocarbon compound includes CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, C1-C5 saturated or unsaturated linear, branched, or cyclic hydrofluorocarbons, such as C4H2F6, CHF3, CH2F2, or combinations thereof; The hydrofluorocarbon or fluorocarbon compound is C4H2F6; The additive compound contains the elements silicon, carbon, and / or iodine having the formula: C n R 1 R 2 R 3 I, SiR 1 R 2 R 3 I, SiR 1 R 2 I x F (2-x) , Sir y F (3-y) , SiI z F (4-z) or C n F (2n+1) I (Wherein, n=1 to 10; x=1 to 2; y=1 to 3; z=1 to 3; R, R 1 , R 2, and R 3 are each independently H, C1 to C 10 R is selected from linear, branched or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl groups; 1 and R 2 , R 2 and R 3 , or R 1 and R 3 may be linked to form a cyclic group); The additive compound is selected from the following: [ka] [ka] · The above disclosed additive CR 1 R 2 R 3 I contains [ka] · The above-disclosed additive SiR 1 R 2 R 3 I contains [ka] · The above-disclosed additive SiR 1 R 2 I x F (2-x) contains [ka] · The additive SiRI disclosed above y F (3-y) contains [ka] The above-disclosed additive SiI z F (4-z) contains [ka] Disclosed Additive C n F (2n+1) I contains [ka] The additive compound is selected from the following: Iodomethane CH3I (CAS No.: 74-88-4), Iodobenzene C6H5I (CAS No.: 591-50-4), 2-IodopropaneC3H7I(CAS No.:75-30-9), 1-IodopropaneC3H7I(CAS No.:107-08-4), 1-IodoethaneC2H5I(CAS No.:75-03-6), Perfluorobutyl iodide C4F9I (CAS No.: 423-39-2), Difluoroiodomethane CHIF2 (CAS No.: 1493-03-4), Difluoroiodo(pentafluoroethyl)silane C2F7ISi (CAS No.: 36972-59-5), 1-(Difluoroiodosilyl)-2-methylbenzeneC7H7F2ISi(CAS No.:174711-76-3), Difluoroiodo(trifluoromethyl)silane CF5ISi (CAS No.: 27668-68-4), Triethyliodosilane C6H 15 ISi (CAS No.: 1112-49-8), Fluorotriiodosilane FI3Si (CAS No.: 16865-60-4), Bifluoroiodosilane F2I2Si (CAS No.: 27669-15-4), Trifluoroiodosilane F3ISi (CAS No.: 27668-68-4), Iodotrimethylsilane, C3H9ISi (CAS No.: 16029-98-4), or Diiodosilane SiH2I2 (CAS number: 13760-02-6); The additive compound is iodomethane CH3I (CAS number: 74-88-4); · The additive compound is iodobenzene C6H5I (CAS number: 591-50-4);· The additive compound is 2-iodopropane C3H7I (CAS number: 75-30-9); The additive compound is 1-iodopropane C3H7I (CAS number: 107-08-4); · The additive compound is 1-iodoethane C2H5I (CAS number: 75-03-6);· The additive compound is perfluorobutyl iodide C4F9I (CAS number: 423-39-2); The additive compound is difluoroiodomethane CHIF2 (CAS No.: 1493-03-4); The additive compound is difluoroiodo(pentafluoroethyl)silane C2F7ISi (CAS number: 36972-59-5); The additive compound is difluoroiodo(pentafluoroethyl)silane C2F7ISi (CAS number: 36972-59-5); The additive compound is 1-(difluoroiodosilyl)-2-methyl-benzeneC7H7F2ISi (CAS number: 174711-76-3); The additive compound is difluoroiodo(trifluoromethyl)silane CF5ISi (CAS number: 27668-68-4); The additive compound is triethyliodosilane C6H 15 ISi (CAS number: 1112-49-8); The additive compound is fluorotriiodosilane FI3Si (CAS number: 16865-60 -4); The additive compound is bifluorobioiodosilane F2I2Si (CAS number: 27669-15-4); The additive compound is trifluoroiodosilane F3ISi (CAS number: 27668-68-4); The additive compound is iodotrimethylsilane C3H9ISi (CAS number: 16029-98-4); The additive compound is diiodosilane SiH2I2 (CAS number: 13760-02-6); the film is a silicon-containing film comprising O and / or N, and optionally comprising dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof; The film is a silicon-containing film that contains O; The film is a silicon-containing film that contains N; the film is a silicon-containing film, optionally including dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof; Silicon-containing films include silicon oxide (SiO), silicon nitride (SiN), crystalline Si, polysilicon (p-Si), polycrystalline silicon, amorphous silicon, low-k SiCOH, SiOCN, SiC, SiON, and Si a O b H c C d N e (a>0; b, c, d, e≥0), including alternating layers of SiO and SiN (ONON), and alternating layers of SiO and p-Si (OPOP); · the silicon-containing film contains oxygen, nitrogen, carbon, hydrogen, or a combination thereof; Silicon-containing film is SiO x N y H z C k wherein x ranges from 0 to 2, y ranges from 0 to 4, z ranges from 0 to about 1, and k ranges from 0 to 1; The silicon-containing film comprises a SiO layer; The silicon-containing film is a SiN layer; · The silicon-containing film contains alternating layers of SiO and SiN(ONON); The silicon-containing film contains alternating layers of SiO and p-Si (OPOP); The silicon-containing film includes dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge; · Alternating layers of silicon oxide, silicon nitride, polysilicon, crystalline silicon, SiOCH, SiON, Si a O b Cc N d H e (a>0; b, c, d, e≧0), or a combination thereof; · the alternating layers include oxygen atoms, nitrogen atoms, carbon atoms, hydrogen atoms, or combinations thereof; · the alternating layers are silicon-containing films; · the alternating layers include layers of silicon oxide and layers of silicon nitride; · the alternating layers include alternating layers of silicon oxide and silicon nitride; · The alternating layers are of silicon oxide and silicon nitride; · the alternating layers include layers of silicon oxide and layers of polysilicon; · the alternating layers include alternating layers of silicon oxide and polysilicon; · The alternating layers are of silicon oxide and polysilicon; · Alternating layers are selectively etched from the hardmask layer; · Alternating layers are selectively etched from the aC layer; · Alternating layers are selectively etched from the doped carbon layer; · Alternating layers of silicon oxide and silicon nitride are selectively etched from the aC layer; · Alternating layers of silicon oxide and silicon nitride are selectively etched from the doped carbon layer; · Alternating layers of silicon oxide and polysilicon are selectively etched from the aC layer; · Alternating layers of silicon oxide and polysilicon are selectively etched from the doped carbon layer; · The silicon oxide layer is selectively etched from the hard mask layer; · The silicon oxide layer is selectively etched from the aC layer; · The silicon oxide layer is selectively etched from the doped carbon layer; · The silicon nitride layer is selectively etched from the hard mask layer; · The silicon nitride layer is selectively etched from the aC layer; · The silicon nitride layer is selectively etched from the doped carbon layer; · The polysilicon layer is selectively etched from the hard mask layer; · The polysilicon layer is selectively etched from the aC layer; · The polysilicon layer is selectively etched from the doped carbon layer; · The silicon-containing film is selectively etched from an amorphous carbon layer, a doped amorphous carbon layer, a photoresist layer, an antireflective layer, or an organic planarization layer; The silicon oxide layer is selectively etched from the amorphous carbon layer, the doped amorphous carbon layer, the photoresist layer, the antireflective layer, or the organic planarization layer; · The etching compound etches both silicon oxide and silicon nitride layers with a high etching rate; The patterned mask layer is an aC layer, a doped aC layer, a photoresist layer, an anti-reflective layer, an organic planarization layer, a poly-Si layer, a metal oxide layer, e.g., oxides of Ti, Al, Zr, Hf, etc., and combinations thereof; A hard mask layer is disposed over the silicon-containing layer; The hardmask layer is a patterned hardmask layer; The hardmask layer is an amorphous carbon layer, a doped amorphous carbon layer, a photoresist layer, an antireflective layer, an organic planarization layer, or a combination thereof; · the hardmask layer is a layer of CVD, PECVD, ALD, PEALD, or spin-on-deposited (SOD) amorphous carbon or doped amorphous carbon, silicon-containing spin-on mask, or carbon-containing spin-on mask; The hard mask layer is an amorphous carbon (aC) layer; The hard mask layer is a doped carbon layer; The doped amorphous carbon layer is a boron doped aC layer; The doped amorphous carbon layer is a tungsten doped aC layer; The HAR patterned structure formed on the film has an aspect ratio of about 1:1 to about 200:1; The HAR patterned structure formed on the film has an aspect ratio of about 1:1 to about 20:1; · the HAR patterned structure formed in the film has an aspect ratio of about 21:1 to about 60:1; · the HAR patterned structure formed in the film has an aspect ratio of about 21:1 to about 200:1; · the HAR patterned structure formed on the film has an aspect ratio of about 61:1 to about 200:1; introducing an additional etching gas into the reaction chamber, the additional etching gas being cC4F8, C4F8, cC5F8, C5F8, C4F6, CF4, CH3F, CF3H, CH2F2, C3HF7, C3F6, C3H2F6, C3H2F4, C3H3F5, C4HF7, C5HF9, C3F6, C3F8, CF3I, C2F3I, C2F5I, C3F7I, 1-iodoheptafluoropropane (1-C3F7I), 2-iodoheptafluoropropane (2-C3F7I ), C3HF7, COS, FNO, FC≡N, CS2, SO2, SF6, trans-1,1,1,4,4,4-hexafluoro-2-butene (trans-C4H2F6), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C4H2F6), hexafluoroisobutene (C4H2F6), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C4H2F6), 1,1,2,2,3-pentafluorocyclobutane (C4H3F5), 1,1 , 2,2-tetrafluorocyclobutane (C4H4F4), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6), and combinations thereof; · Introduce the etching compounds and additives separately from the additional etching gas; Adding about 0.01% v / v to about 99.99% v / v of additional etching gas to the etching compound and additives; ·Applying RF power to activate the plasma; Activating the plasma with RF power ranging from about 25 W to about 100,000 W; · Lower bias power by using additives containing hydrofluorocarbons or fluorocarbons compared to etching without additives; · the use of the hydrofluorocarbon or fluorocarbon containing additive results in a bias power that is at least about 10% lower than without the additive; The etching pressure is in the range of about 1 mTorr to about 100 Torr; The etching pressure is in the range of about 1 mTorr to about 50 Torr; The etching pressure is in the range of about 1 mTorr to about 10 Torr; The etching pressure is in the range of about 1 mTorr to about 50 mTorr; introducing vapors of the etching compound and additive at flow rates ranging from about 0.1 sccm to about 1 slm; introducing vapor of an etching compound at a flow rate ranging from about 0.1 sccm to about 1 slm; introducing additive vapor at a flow rate ranging from about 0.1 sccm to about 1 slm; · maintaining the substrate at a temperature in the range of about -100°C to about 500°C; · maintaining the substrate at a temperature in the range of about 20°C to about 150°C; maintaining the substrate at a temperature in the range of about 20° C. to about 110° C.; and ·Measure the etching compounds under plasma by quadrupole mass spectrometry, optical emission spectrometry, FTIR or other radical / ion measurement tools.

[0013] Also disclosed is a method of forming a HAR patterned structure, the method comprising: exposing a substrate to vapors of C4H2F6 and CH3I, either sequentially or simultaneously, the substrate having a film disposed thereon and a patterned mask layer disposed on the film; activating the plasma to produce activated C4H2F6 and CH3I; and allowing an etching reaction to proceed between the film not covered by the patterned mask layer and the activated C4H2F6 or CH3I to selectively etch the film from the patterned mask layer, thereby forming a HAR patterned structure; The disclosed methods may include one or more of the following aspects: further comprising the step of introducing an oxidant into the reaction chamber, the oxidant being selected from O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof; further comprising the step of introducing an inert gas into the reaction chamber, the inert gas being selected from the group consisting of He, Ar, Xe, Kr, Ne, and N2; A highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structures; the electrical conductivity of the highly conductive sidewall passivation layer formed using activated C4H2F6 and activated CH3I is at least about 10% higher than the electrical conductivity of a highly conductive sidewall passivation layer formed using activated C4H2F6 without the addition of activated CH3I; The HAR patterned structure formed on the film has an aspect ratio of about 1:1 to about 200:1; Further comprising introducing an additional etching gas into the reaction chamber, the additional etching gas being selected from the group consisting of cC4F8, C4F8, cC5F8, C5F8, C4F6, CF4, CH3F , CF3H, CH2F2, C3HF7, C3F6, C3H2F6, C3H2F4, C3H3F5, C4HF7, C5HF9, C3F6, C3F8, CF3I, C2F3I, C2F5I, C3F7I, 1-iodoheptafluoropropane (1-C3F7I), 2-iodoheptafluoropropane (2-C3F7I), C3HF7, COS, FNO, FC≡N, CS2, SO2, SF6, trans-1,1,1,4,4,4-hexafluoro-2-butene (trans-C4H2F6), cis-1,1,1, selected from the group consisting of 4,4,4-hexafluoro-2-butene (cis-C4H2F6), hexafluoroisobutene (C4H2F6), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C4H2F6), 1,1,2,2,3-pentafluorocyclobutane (C4H3F5), 1,1,2,2-tetrafluorocyclobutane (C4H4F4), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6), and combinations thereof; and The film is a silicon-containing film comprising O and / or N, and optionally comprising dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

[0014] Designation and nomenclature In the following detailed description and claims, a number of abbreviations, symbols and terms that are commonly known in the art are utilized, including the following:

[0015] As used herein, the indefinite article "a" or "an" means one or more.

[0016] As used herein, in the text or claims, "about" or "approximately" or "approximately" means ±10% of the stated value.

[0017] As used herein, "room temperature" in the text and claims means about 20°C to about 25°C.

[0018] The term "wafer" or "patterned wafer" refers to a wafer having any pre-existing film stack, including silicon-containing films, on a substrate and a patterned hard mask layer on any pre-existing film stack, including silicon-containing films, formed for pattern etching.

[0019] The term "substrate" refers to one or more materials on which a process is performed. A substrate may refer to a wafer or a patterned wafer having one or more materials on which an etching process is performed. A substrate may be any suitable wafer used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. A substrate may also have one or more layers of different materials already deposited thereon from a previous manufacturing step. For example, a wafer may include a silicon layer (e.g., crystalline, amorphous, porous, etc.), a silicon-containing layer (e.g., SiO2, SiN, SiON, SiCOH, etc.), a metal-containing layer (e.g., copper, cobalt, ruthenium, tungsten, indium, platinum, palladium, nickel, ruthenium, gold, etc.), or a combination thereof. Furthermore, a substrate may be flat or patterned. A substrate may be a photoresist film patterned with an organic. The substrate may be a layer of oxide (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 MEMS, 3D NAND, MIM, DRAM, or FeRam device applications, a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode, or a metal-containing or metal alloy-based film (e.g., InGaAs, InGaAs) that is a promising candidate to replace silicon in future CMOS systems. x O y (x=0.5~1.5, y=0.5~1.5), InSnO (ITO), InGaZnO (IGZO), InN, InP, In As, InSb, In2S3, or In(OH)3, etc. One of ordinary skill in the art will recognize that the term "film" or "layer" as used herein refers to a thickness of any material disposed or spread over a surface, which may be a trench or a line. Throughout this specification and claims, the wafer and associated layers thereon are referred to as the substrate.

[0020] The terms "pattern etch" or "patterned etch" refer to etching a non-planar structure, such as a stack of silicon-containing films, underneath a patterned hardmask layer.

[0021] As used herein, the term "etch" or "etching" means the use of an etching compound and / or plasma to remove material by ion bombardment, remote plasma, or chemical vapor phase reaction between an etching gas and a substrate, and refers to isotropic and / or anisotropic etching processes. Isotropic etching processes involve a chemical reaction between an etching compound and a substrate, which removes a portion of the material on the substrate. This type of etching process includes chemical dry etching, vapor phase chemical etching, thermal dry etching, and the like. Isotropic etching processes produce lateral or horizontal etching profiles in the substrate. Isotropic etching processes produce recesses or horizontal recesses in the sidewalls of preformed apertures in the substrate. Anisotropic etching processes include plasma etching processes (i.e., dry etching processes) in which chemical reactions are accelerated vertically by ion bombardment, resulting in the formation of vertical sidewalls perpendicular to the substrate along the edges of masked features (Manos and Flamm, Thermal etching an Introduction, Academic Press, Inc. 1989 pp.12-13). The plasma etching process creates vertical etch profiles in the substrate. The plasma etching process creates vertical vias, apertures, trenches, channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, slit etches, self-aligned contacts, self-aligned vias, supervias, etc. in the substrate.

[0022] The term "mask" refers to a layer that resists etching. A mask layer can be placed over a layer to be etched. A mask layer also refers to a hard mask layer. A mask layer can be an amorphous carbon (aC) layer, a doped aC layer, a photoresist layer, an anti-reflective layer, an organic planarization layer, and combinations thereof. A mask layer can be a silicon layer such as poly-Si, a metal oxide such as Ti, Al, Zr, Hf, an oxide, and combinations thereof.

[0023] The term "aspect ratio" refers to the ratio of the height of a trench (or an aperture) to the width of the trench (or the diameter of the aperture).

[0024] The term "etch stop" refers to a layer below the layer being etched that protects the layer below.

[0025] The term "device channel" refers to a layer that is part of the actual device and any damage to it will affect device performance.

[0026] The term "selectivity" refers to the ratio of the etch rate of one material to the etch rate of another material. The terms "selective etch" or "selective etching" refer to etching one material over another, or in other words, an etch selectivity between two materials that is greater than or less than 1:1.

[0027] The terms "via," "aperture," "trench," and "hole" may be used interchangeably and generally refer to an opening in an interlayer dielectric.

[0028] The terms "low bias power" or "reduced bias power" refer to a bias power that is lower than a baseline process.

[0029] The term "additive" as used herein refers to a compound or gas that is added to other etching compounds to improve some characteristic of the etch, such as improving profile characteristics such as bowing, CD, ellipticity, etc.

[0030] The term "ellipticity" as used herein refers to a method of measuring mask degradation, and in etching applications, the ellipticity of an etched hole is estimated by (width of short hole / width of long hole)*100% for simplicity; therefore, the ellipticity of a perfect circle was defined as 100%.

[0031] As used herein, the abbreviation "NAND" refers to a "Negated AND" or "Not AND" gate, the abbreviation "2D" refers to a two-dimensional gate structure on a flat substrate, and the abbreviation "3D" refers to a three-dimensional or vertical gate structure in which the gate structures are stacked vertically.

[0032] The term "mercury probe" as used herein refers to an electrical probe device for rapid and non-destructive contact with a sample for electrical characterization. If the mercury-sample contact is ohmic (non-rectifying), a current-voltage instrument can be used to measure resistance, leakage current, or current-voltage characteristics. Resistance can be measured on bulk samples or thin films. Thin films can be composed of any material that does not react with mercury. The diameter of the mercury contact of the mercury probe as used herein is 760 um.

[0033] As used herein, the term "electrical conductivity" is the inverse of electrical resistivity and describes the ability of a material to pass electric current. The unit of electrical conductivity as used herein is Siemens per centimeter (S / cm). It is measured using a mercury probe and is

number

[0034] As used herein, the term "highly conductive sidewall passivation layer" refers to a sidewall passivation layer with an electrical conductivity that exceeds the conductivity of the C4F8 polymer, which is 2.14×10 -9Calculated as S / cm.

[0035] It should be noted that the terms "film" and "layer" may be used interchangeably herein. It is understood that a film may correspond to or relate to a layer, and that a layer may be referred to as a film. Furthermore, one skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a thickness of some material applied or spread over a surface, and that the surface may range from as large as an entire wafer to as small as a trench or line.

[0036] It should be noted that, as used herein, the terms "etching compound," "etchant," "etching gas," and "process gas" may be used interchangeably when the etching compound is in a gaseous state at room temperature and ambient pressure. It is understood that an etching compound may correspond to or relate to an etching gas or etchant or process gas, and an etching gas or etchant or process gas may refer to an etching compound.

[0037] Standard abbreviations of elements from the periodic table are used herein. It should be understood that elements can be represented by these abbreviations (e.g., Si means silicon, N means nitrogen, O means oxygen, C means carbon, H means hydrogen, F means fluorine, etc.).

[0038] Unique CAS Registry Numbers assigned by the Chemical Abstract Service (ie, "CAS") are provided to identify particular molecules disclosed.

[0039] It should be noted that silicon-containing films such as SiN and SiO are recited throughout the specification and claims without indicating their appropriate stoichiometry. Silicon-containing films include pure silicon (Si) layers such as crystalline Si, polysilicon (p-Si or polycrystalline Si) or amorphous silicon; silicon nitride (Si k N l) layer; silicon oxide (Si n O m ) layer; or a mixture thereof, where k, l, m and n are inclusively in the range of 0.1 to 6. Preferably, the silicon nitride is a SiN layer, where k and I are in the range of 0.5 to 1.5, respectively. k N l More preferably, the silicon nitride is Si3N4. In the following description, SiN is Si k N l It may be used to represent the containing layer. Preferably, silicon oxide is Si, where n is in the range of 0.5 to 1.5 and m is in the range of 1.5 to 3.5. n O m More preferably, the silicon oxide is SiO2. In the present specification and the following, SiO means Si n O m may be used to represent a containing layer. The silicon-containing film may be a silicon oxide-based dielectric material, such as an organic-based or silicon oxide-based low-k dielectric material, such as Black Diamond II or III materials by Applied Materials, Inc., which have SiOCH. The silicon-containing film may be a Si-containing layer, where a, b, and c are in the range of 0.1 to 6. a O b N c The silicon-containing film may also include dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

[0040] The term "independently" when used in the context of describing an R group should be understood to mean that the R group in question is selected independently not only with respect to other R groups having the same or different subscripts or superscripts, but also with respect to any additional species of the same R group. For example, 1 x (NR 2 R 3 ) (4-x) (M is an atom, and x is 2 or 3), 1 The groups may be mutually exclusive or R 2 Or R3 It may be, but is not necessarily, the same as: Furthermore, unless otherwise specified, it should be understood that the values ​​of R groups are independent of each other when used in different formulas.

[0041] 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 said ranges.

[0042] References herein to "one embodiment" or "an embodiment" imply that a particular feature, structure, or characteristic described in connection with the embodiment is applicable to at least one embodiment of the present invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, and different or alternative embodiments are not necessarily mutually exclusive of other embodiments. The same applies to the term "implementation."

[0043] For a better understanding of the nature and objects of the present invention, the following detailed description should be read in conjunction with the accompanying drawings, in which like elements are given the same or similar reference numerals, and in which: [Brief description of the drawings]

[0044] [Figure 1] Measured conductivity of C4H2F6 with and without the additive CH3I on a flat wafer. [Diagram 2] 4 is the conductivity of C4H2F6 with and without the additive C4F9I measured on a flat wafer. [Diagram 3] Measured conductivity of C4H2F6 with and without the additive SiH2I2 on a flat wafer. [Figure 4] ER and selectivity comparison of C4H2F6 with and without additive CH3I, respectively. [Diagram 5] 1 is a comparison of sidewall bowing of C4H2F6 with and without additive CH3I. [Figure 6] A comparison of ellipticity with and without additive CH3I. [Figure 7] 1 is a comparison of critical dimensions (CD) of C4H2F6 with and without CH3I additive at a bias power of 7000 W. [Figure 8] A comparison of the CD of C4H2F6 with and without CH3I additive at a bias power of 5600 W. [Figure 9] A comparison of the CD of C4H2F6 with and without CH3I additive at a bias power of 4200 W. [Figure 10] The chemical composition of various polymers and the electrical conductivity of the polymers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] A method is disclosed for forming a highly conductive sidewall passivation layer on the sidewalls by doping with Si, C, and / or iodine elements in a high aspect ratio (HAR) plasma etch process using an etch gas as an additive. The disclosed method uses an additive or additive chemical in the HAR plasma etch process to form a highly conductive sidewall passivation layer by doping with Si, C, and / or iodine elements. The highly conductive sidewall passivation layer may be a polymer passivation layer. The conductive state of the polymer passivation layer reduces charge accumulation along the sidewalls, prevents twisting of HAR structures such as holes by bleeding off the charge, and ensures proper control of critical dimension (CD) variations at low to no bias power. By utilizing the additive, the bias power may be at least about 10% lower than without the use of the additive, or even eliminates the need for bias power.

[0046] With minimized sidewall charge, less plasma bias power is required for reactive ions to reach the bottom of the HAR trench, and the disclosed method can also be considered as a low bias energy plasma etch. Additionally, the etch or process gases containing the disclosed additives do not contain elements that are difficult to clean, which also minimizes contamination of the reaction chamber and reduces tool maintenance / downtime.

[0047] The disclosed method uses a hydrofluorocarbon etchant gas and an additive gas. and plasma etching the patterned wafer or substrate under reduced bias power for a predetermined time, which may range from 0 to 1000 seconds to allow the pressure and gas flows in the chamber to stabilize before activating the plasma.

[0048] The disclosed additives or additive chemicals include the elements Si, C, and / or iodine having the following formula: CR 1 R 2 R 3 I, SiR 1 R 2 R 3 I, SiR 1 R 2 I x F (2-x) , Sir y F (3-y) , SiI z F (4-z) or C n F (2n+1) I (Wherein, x=1 to 2; y=1 to 3; z=1 to 4; R, R 1 , R 2 , and R 3 are each independently H, D (deuterium), C1 to C 10R is selected from linear, branched, or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted alkyl groups. 1 and R 2 , R 2 and R 3 , or R 1 and R 3 may be linked to form a cyclic group.

[0049] The above disclosed additive CR 1 R 2 R 3 I may include: [ka]

[0050] The additive SiR 1 R 2 R 3 I may include: [ka]

[0051] The additive SiR 1 R 2 I x F (2-x) may include the following: [ka]

[0052] The additive SiRI disclosed above y F (3-y) may include the following: [ka]

[0053] The additive SiI disclosed above z F (4-z) may include the following: [ka]

[0054] Disclosed Additive C n F (2n+1) I may include: [ka]

[0055] Exemplary disclosed additives containing the elements Si, C, and / or iodine are listed in Table 1. These molecules are commercially available or can be synthesized by methods known in the art. Their structural formulas, CAS numbers, and boiling points are shown in the table. The disclosed additives containing the elements Si, C, and / or iodine can also include their isomers.

[0056] [Table 1]

[0057] [Table 2]

[0058] High volatility is preferred for the etching gas, so high volatility is also required for the additive chemistry. As mentioned above, small alkyl groups are used as the substituents on the silicon of the additive, which gives the disclosed additives high volatility. Another advantage provided by the use of alkyl substituents is that the generation of insufficient carbon leaving groups increases the likelihood of carbon incorporation into the sidewall passivation. The use of aromatic substituents on silicon has also been proposed in new molecules, as the inclusion of aromatic groups in the sidewall passivation can improve electrical conductivity. Substitutions on aromatic groups are also of interest, as they can change the electronics of the aromatic rings in electrical conductivity. However, those skilled in the art will appreciate that low volatility etching materials can also be used. Low volatility etching materials can be achieved by heating a container or cylinder containing the low volatility etching material and a gas line connecting to the etching tool, and blowing an inert gas through the liquid low volatility etching material. The etching material may be used in a variety of ways, including by using a bubbler technique in which a source of low volatility etching material is heated to increase its volatility.

[0059] The disclosed additives are suitable for tuning the properties of the passivation layer formed on the sidewalls of high aspect ratio holes / trenches. Sidewall passivation and downward etching occur simultaneously. The passivation layer can originate from a carbon source in the plasma etching gas, a reaction between the etching gas and the exposed material, or redeposition of by-products from the etching process. The additives to the etchant significantly affect the chemical composition of the sidewall passivation by introducing conductive elements and / or chemical bonds, thereby positively affecting the conductivity of the sidewall passivation. During the plasma etching process, the potential at the bottom of the structure becomes positively charged while the sidewalls become negatively charged, thus forming an undesirable local electric field within the structure. Only energetic ions with energy greater than the potential difference along the local electric field can reach the bottom. As the conductivity of the sidewall passivation increases, the charge on the sidewall dissipates rapidly. The required bias power is lower than the baseline process.

[0060] The disclosed etching gases may be fluorocarbons / hydrofluorocarbons. Exemplary disclosed fluorocarbons / hydrofluorocarbons include CF4, CH3F, C2F6, C3F8, C2HF5, C5F8, C6F6, C4F6, C4F8, C1-C5 saturated or unsaturated linear, branched, cyclic hydrofluorocarbons such as C4H2F6, CHF3, CH2F2, or combinations thereof.

[0061] The disclosed fluorocarbons / hydrofluorocarbons include silicon oxide (SiO), silicon nitride (SiN), pure silicon (Si) (such as crystalline Si), polysilicon (p-Si or polycrystalline Si); amorphous silicon, low dielectric constant SiCOH, SiOCN, SiC, SiON, and Si a O b H c C d N e(a>0; b, c, d, e≧0); suitable for etching silicon-containing films including layers such as metal-containing films (e.g., copper, cobalt, ruthenium, tungsten, indium, platinum, palladium, nickel, ruthenium, gold, etc.). The silicon-containing film may include alternating layers of SiO and SiN (ONON), alternating layers of SiO and p-Si (OPOP). The silicon-containing film includes O and / or N. The silicon-containing film may also include dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

[0062] The disclosed fluorocarbons / hydrofluorocarbons and additives are provided with a purity of greater than 95% v / v, preferably greater than 99.99% v / v, and more preferably greater than 99.999% v / v. The disclosed fluorocarbons / hydrofluorocarbons and additives contain less than 5% by volume of trace gas impurities, including impurity gases such as N2 and / or H2O and / or CO2, less than 150 ppm by volume. Preferably, the water content in the plasma etching gas is less than 20 ppm by weight. Purified products can be produced by distillation and / or passing the gas or liquid through a suitable adsorbent, such as a 4 Å molecular sieve.

[0063] The disclosed fluorocarbons / hydrofluorocarbons and additives contain less than 10% v / v, preferably less than 1% v / v, more preferably less than 0.1% v / v, even more preferably less than 0.01% v / v of any of its isomers, which can be purified by distillation of the gas or liquid to remove the isomers and provide better process repeatability.

[0064] The disclosed fluorocarbons / hydrofluorocarbons are used to deposit the carbide from a buried landing layer or material, which in most applications is a metal layer located at the bottom of the structure being etched. The fluorine-containing layer is selectively etched. The disclosed fluorocarbons / hydrofluorocarbons do not etch the metal landing layer. The buried landing layer may be an etch stop layer or a diffusion barrier layer. The material of the metal landing layer may be the tungsten metal world line of the 3D NAND structure, and / or another metal such as W, Cu, Al, Ru, Pt, Ti, Ta, Ni, Co, Mo, Mn, Pd, Ir, Nb, Cr, Rh, V, Au, Ag, or a combination thereof, and / or an etch stop layer such as a metal or metal oxide or nitride layer (such as AlO, WO, HfO, TiO, TaO, InO, CrO, RuO, CoO, MoO, ZrO, SnO, TiN, TaN, HfN, AlN, WN, MoN, NiN, NbN, CrN, RuN, CoN, ZrN, SnN, or a combination thereof).

[0065] The disclosed fluorocarbons / hydrofluorocarbons can be used to plasma etch silicon-containing films on substrates. The disclosed plasma etching methods can be useful in the fabrication of semiconductor devices such as NAND or 3D NAND gates, or flash or DRAM memories or transistors such as fin-shaped field-effect transistors (FinFETs), gate-all-around (GAA) FETs, nanowire FETs, nanosheet FETs, fork-sheet FETs, complementary FETs (CFETs), bulk complementary metal oxide semiconductors (bulk CMOS), MOSFETs, fully depleted silicon-on-insulator (FD-SOI) structures. The disclosed iodine-containing etching compounds can be useful in other areas of applications such as different front end of the line (FEOL) and back end of the line (BEOL) etching applications. Additionally, the disclosed iodine-containing etching compounds can be used to interconnect memory to logic on substrates, to etch Si in 3D through silicon via (TSV) etching applications, and in MEMS applications.

[0066] The disclosed etching method includes providing a reaction chamber having a substrate disposed therein. The reaction chamber can be any enclosure or chamber in a device in which an etching method is performed, such as, but not limited to, a reactive ion etch (RIE), CCP with single or multiple frequency RF sources, inductively coupled plasma (ICP), or microwave plasma reactor, or other types of etching systems capable of selectively removing portions of silicon-containing films or generating active species. Those skilled in the art will recognize that different plasma reaction chamber designs provide different electronic temperature control. Suitable commercially available plasma reaction chambers include, but are not limited to, Applied Materials magnetically enhanced reactive ion etcher sold under the trademark eMAX™, or Lam Research Dual CCP reactive ion etcher dielectric etching product line sold under the trademark 2300® Flex™, or Advanced Micro-Fabrication Equipment Inc. China (AMEC) Primo SSC HD-RIE etcher. The RF power therein can be pulsed to control the plasma characteristics and thereby further improve the etching performance (selectivity and damage).

[0067] The reaction chamber may contain one or more than one substrate. For example, the reaction chamber may contain 1 to 200 silicon wafers with diameters between 25.4 mm and 450 mm. The substrate may be any suitable substrate used in semiconductor, photovoltaic, flat panel or LCD-TFT device manufacturing. Examples of suitable substrates include wafers such as silicon, silica, glass, Ge, SiGe, GeSn, InGaAs, GaSb, InP or GaAs wafers. The wafers may be wafers that have been subjected to a previous manufacturing step, including a silicon-containing film or layer. The substrate will have multiple films or layers thereon from the substrate. The layers may be patterned or unpatterned. Examples of suitable layers include, but are not limited to, silicon (amorphous silicon, p-Si, crystalline silicon, any of which may be further p-doped or n-doped with B, C, P, As, Ga, In, Sn, Sb, Bi and / or Ge), silica, silicon nitride, silicon oxide, silicon oxynitride, Si a O b H c C d N e where a>0; b, c, d, e>0; Ge, SiGe, GeSn, InGaAs, GaSb, InP; mask layer materials such as amorphous carbon with or without dopants, anti-reflective coatings, photoresist materials, metal oxides such as AlO, TiO, HfO, ZrO, SnO, TaO, or metal nitride layers such as AlN, ZrN, SnN, HfN, titanium nitride, tantalum nitride, etc., or combinations thereof; silicon nitride, polysilicon, crystalline silicon, silicon carbide, SiON, SiCN, or combinations thereof; device channel materials such as crystalline silicon, epitaxial silicon, doped silicon, Si a O b H c C d N e and etch stop layer materials such as SiO2, SiO3, SiO4, SiO5, SiO6, SiO7, SiO8, SiO9, SiO10, SiO21, SiO22, SiO33, SiO44, SiO55, SiO6, SiO7, SiO8, SiO9, SiO10, SiO23, SiO24, SiO25, SiO26, SiO27, SiO28, SiO29, SiO21, SiO22, SiO23, SiO24, SiO25, SiO26, SiO27, SiO28, SiO29 ... II or III by Applied Materials. Additionally, layers containing tungsten or precious metals (e.g., platinum, palladium, rhodium, or gold) may be used. Additionally, examples of silicon-containing films include Si a O b H c C d N e where a>0; b, c, d, e>0. Throughout the specification and claims, the wafer and any associated layers thereof are referred to as the substrate.

[0068] The disclosed etching method includes pumping the reaction chamber to a high vacuum after placing the substrate in the chamber and before introducing the disclosed fluorocarbon / hydrofluorocarbon into the chamber, which can range from 0.01 mTorr to 10 mTorr.

[0069] An inert gas is also introduced into the reaction chamber to receive the plasma. The inert gases include He, Ar, Xe, Kr, Ne, N 2、 The etching gas may be, for example, 0.01% v / v to about 99.9% v / v of the resulting mixture, preferably 0.01% v / v to about 99.9% v / v of the inert gas, or a combination thereof. The etching gas and the inert gas may be mixed prior to introduction into the chamber, such that the inert gas comprises from about 0.01% v / v to about 99.9% v / v of the resulting mixture. Alternatively, the inert gas may be continuously introduced into the chamber, while the etching gas is intermittently introduced into the chamber.

[0070] The disclosed etching gas vapors and inert gases are activated by plasma to produce activated etching gas. The plasma breaks down the etching gas into radical form (i.e., activated etching gas). The plasma may be generated by applying RF or DC power. The plasma may be generated by RF power ranging from about 25 W to about 100,000 W. The plasma may be generated remotely or within the reactor itself. The plasma may be generated in dual CCP or ICP mode with RF applied at both electrodes. The RF frequency of the plasma may range from 100 KHz to 1 GHz. Different RF sources at different frequencies may be combined and applied at the same electrode. Further plasma RF pulses may be used to control molecular fragmentation and reactions at the substrate. Those skilled in the art will recognize suitable methods and apparatus for such plasma processing.

[0071] The activated etching gas from the chamber exhaust may be measured by a quadrupole mass spectrometer (QMS), optical emission spectrometer, FTIR or other radical / ion measurement tool to determine the type and number of species generated. If necessary, the flow rates of the etching gas and / or inert gas may be adjusted to increase or decrease the number of radical species generated.

[0072] The disclosed etching gases and additives may be mixed with other gases or co-reactants either prior to introduction into the reaction chamber or in the reaction chamber. Preferably, the gases are mixed prior to introduction into the chamber to provide a uniform concentration of the entrained gases.

[0073] In another option, vapors of the hydrofluorocarbon etching compound and additive may be introduced into the chamber independently from other gases, such as when two or more gases react or are easier to deliver independently.

[0074] In another option, the hydrofluorocarbon etch gas and the additive gas are the only two gases used during the etching process.

[0075] In another alternative, the hydrofluorocarbon etch gas, the additive gas, and the inert gas are the only three gases used during the etching process.

[0076] Exemplary other gases or co-reactants include, but are not limited to, oxidizers such as O2, O3, CO, CO2, NO, N2O, NO2, H2O, H2O2, COS, SO2, and combinations thereof. The disclosed etching gases / additives and oxidizers may be mixed together prior to being introduced into the reaction chamber.

[0077] Alternatively, the oxidizer can be continuously introduced into the chamber and the etching gas intermittently introduced into the chamber. The oxidizer may comprise from about 0.01% v / v to about 99.99% v / v of the mixture introduced into the chamber (99.99% v / v represents the introduction of nearly pure oxidizer for the continuous introduction option).

[0078] Other exemplary gases with which the disclosed hydrofluorocarbon etch and additive gases may be used include cC4F8, C4F8, cC5F8, C5F8, C4F6, CF4, CH3F, CF3H, CH2F2, C3HF7, C3F6, C3H2F6, C3H2F4, C3H3F5, C4HF7, C5HF9, C3F6, C3F8, CF3I, C2F3I, C2F5I, C3F7I, 1-iodoheptafluoropropane (1-C3F7I), 2-iodoheptafluoropropane (2-C3F7I), C3HF7, COS, FNO, FC≡N, CS2, SO2, H2S, SF6, trans- Examples of iodine-containing etching compounds include 1,1,1,4,4,4-hexafluoro-2-butene (trans-C4H2F6), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C4H2F6), hexafluoroisobutene (C4H2F6), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C4H2F6), 1,1,2,2,3-pentafluorocyclobutane (C4H3F5), 1,1,2,2-tetrafluorocyclobutane (C4H4F4), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6), or combinations thereof. For example, about 1% v / v to about 25% v / v of the disclosed iodine-containing etching compounds may be used, with the remainder being C4F6 or cC4F8. As shown in the examples below, the combination of the disclosed iodine-containing etching compounds with conventional etching gases can provide increased etch rates while maintaining higher selectivity between the substrate and the layer being etched in conjunction with the disclosed iodine-containing etching compounds. It can be achieved.

[0079] Vapors of the disclosed etching compounds and / or additives are introduced into a reaction chamber containing a substrate and a silicon-containing film. The vapors may be introduced into the chamber at flow rates ranging from about 0.1 sccm to about 1 slm, respectively. For example, for a 200 mm wafer size, the vapors may be introduced into the chamber at flow rates ranging from about 5 sccm to about 50 sccm. Alternatively, for a 450 mm wafer size, the vapors may be introduced into the chamber at flow rates ranging from about 25 sccm to about 250 sccm. Those skilled in the art will recognize that flow rates may vary from tool to tool. Vapors of the disclosed etching compounds and / or additives may be introduced into the reaction chamber premixed or separately.

[0080] The disclosed etching compounds and / or additives may be provided either neat or in a blend with a suitable solvent, such as ethylbenzene, xylene, mesitylene, decane, or dodecane. The disclosed compounds and additives may be present in a variety of concentrations in the solvent. The vapor form of the disclosed compounds and additives may be produced by evaporating neat or blended solutions of the disclosed compounds and additives via a conventional evaporation step, such as direct evaporation or bubbling. The neat or blended disclosed compounds and additives may be provided in a liquid state to an evaporator that evaporates it before introducing it into the reactor. Alternatively, the neat or blended disclosed compounds and additives may be evaporated by passing a carrier gas through a vessel containing the disclosed compounds and additives or by bubbling a carrier gas through the disclosed compounds and additives. The carrier gas may include, but is not limited to, Ar, He, N2, Xe, Kr, Ne, and mixtures thereof. The carrier gas and the disclosed compounds and additives are then introduced into the reactor as vapors.

[0081] If necessary, the vessel containing the disclosed compounds and additives may be heated to a temperature at which the disclosed compounds and additives are in liquid phase and have sufficient vapor pressure. The vessel may be maintained at a temperature ranging from about 0° C. to about 150° C., for example. The line from the bubbler to the etching tool may also be maintained at a temperature equal to or greater than the vessel temperature. Those skilled in the art will recognize that the vessel temperature may be adjusted in a known manner to control the amount of the disclosed compounds and additives that are evaporated.

[0082] The disclosed hydrofluorocarbon etching gas and additive gas vapors and the additional etching gas can be mixed prior to being introduced into the reaction chamber, and the additional etching gas can comprise from about 0.01% v / v to about 99.99% v / v of the mixture introduced into the chamber.

[0083] The disclosed etching gas vapors and additional gases such as inert gases and co-reactants are activated by the plasma to produce an activated etching gas. The plasma breaks down the etching gas into radical forms or ions (i.e., activated etching gas). The plasma may be generated by applying RF or DC power. The plasma may be generated by RF source power ranging from about 25 W to about 100,000 W in a decoupled plasma etch reactor. The plasma may be generated remotely or within the reactor itself. The plasma may be generated in dual CCP or ICP mode, including but not limited to, by RF applied at both electrodes. The RF frequency of the plasma may range from 100 KHz to 1 GHz. Different RF sources at different frequencies may be combined and applied at the same electrode. The plasma RF pulse may be further used as a bias power to control molecular fragmentation and reactions at the substrate. Those skilled in the art will recognize suitable methods and apparatus for such plasma processing.

[0084] The disclosed additives, when used with hydrofluorocarbons or fluorocarbons, can result in lower bias powers compared to etching without the additive. In the disclosed method, by utilizing the additive, the bias power can be at least about 10% lower than when no additive is used, as shown in the examples below.

[0085] A disclosed method for forming a highly conductive sidewall passivation layer on a high aspect ratio patterned structure includes: i) introducing a vapor of an etchant into a reactor containing a substrate; ii) forming an ion plasma from the etchant in the reactor by applying a source power; iii) diffusing ions toward the substrate by applying a reduced bias power such that portions of the substrate not covered by a patterned mask layer on the substrate are selectively etched away to form a high aspect ratio patterned structure; and iv) continuing to perform the process for a predetermined time until a highly conductive sidewall passivation layer is formed on the sidewalls of the high aspect ratio patterned structure, and then turning off the source power and the reduced bias power.

[0086] Here, the substrate has a film disposed thereon and a patterned mask layer disposed on the film. The etchant includes a hydrofluorocarbon or fluorocarbon compound and an additive compound. The etchant may also include a co-reactant and / or an inert gas. After the etchant is introduced into the reactor, the etchant is allowed to reach equilibrium. The reduced bias power may be at least 10% lower than without the addition of the additive to the etchant. The predetermined time period ranges from 1 second to 1000 seconds. The ratio of the hydrofluorocarbon or fluorocarbon compound to the additive compound is selected such that the newly formed portions of the sidewall surface are passivated and protected from further etching. The ratio of the hydrofluorocarbon or fluorocarbon compound to the additive compound introduced into the reactor may vary from 1:99 to 99:1 depending on the flow rate.

[0087] Prior to introducing the etchant into the reactor, the reactor may be pumped down to a high vacuum ranging from 0.001 mTorr to 100 mTorr, and after the etching process, the reactor may be purged with an inert gas.

[0088] The temperature of the reaction chamber can be controlled by controlling the temperature of the substrate holder or by controlling the temperature of the reactor walls. The devices used to heat the substrate are known in the art. The reactor walls are heated to a temperature sufficient to prevent condensation on the walls or reactor chamber, especially when a showerhead reactor is used where the substrate temperature is higher than the temperature of the walls. Non-limiting exemplary temperature ranges to which the reactor walls can be heated include from about -100°C (LN temperature) to about 500°C, preferably from about 20°C to about 150°C, more preferably from 20°C to about 110°C.

[0089] The pressure within the reaction chamber is maintained at conditions suitable for the etchant or process gas in the portions of the substrate not covered by the patterned mask layer, where the etchant or process gas may include hydrofluorocarbon or fluorocarbon etching gases, additives, co-reactants, etc. For example, the pressure within the reactor may be maintained at about 1 mTorr to about 100 Torr, preferably about 1 mTorr to about 50 Torr, more preferably about 1 mTorr to about 10 Torr, and even more preferably about 1 mTorr to about 50 mTorr.

[0090] Etch conditions may be varied during the etching process. For example, parameters such as gas flow rate, plasma power, pressure, temperature, etc. may be higher or lower during the beginning of the etch compared to the end of the etch near the bottom of the hole or trench, or may be varied at different times of the etch to improve performance, such as to slow or increase the polymer deposition rate. Different etching gases may be added at different points.

[0091] The disclosed etching method can provide high selectivity to mask layers, photoresists, etch stop layers, and device channel materials, and no profile distortion in HAR structures, such as DRAM and 3D NAND structures, having aspect ratios ranging from 1:1 to 200:1, and contact etching applications. Alternatively, aspect ratios ranging from 1:1 to 20:1, and aspect ratios ranging from 21:1 to 200:1. The disclosed etching method is suitable for etching HAR patterned structures having aspect ratios of 1:1 to 200:1. Alternatively, the disclosed etching method is suitable for etching HAR patterned structures having aspect ratios of about 1:1 to about 20:1, aspect ratios between about 21:1 to about 200:1, aspect ratios of about 1:1 to about 60:1, or aspect ratios of about 61:1 to about 200:1. EXAMPLES

[0092] The following non-limiting examples are provided to further illustrate embodiments of the present invention, however, the examples are not intended to be comprehensive and are not intended to limit the scope of the invention described herein.

[0093] In the following examples, experiments were performed using a commercial LAM tool 4520XLe 200 mm (CCP dual frequency plasma) or a commercial AMEC 300 mm Primo SSC HD-RIE etcher. To demonstrate reproducibility, each etch test was repeated at least three times. The standard deviation of the mean of the triplicate measurements is shown as the error bar in the chart. The composition of the polymer was then investigated by X-ray photoelectron spectroscopy (XPS).

[0094] Example 1: Measurement of electrical conductivity of polymers Figures 1-3 show the conductivity of C4H2F6 with and without additives CH3I, C4F9I, or SiH2I2, respectively, measured on flat wafers. The current (I)-voltage (V) was measured using a mercury probe. A drop of deionized water was added to the backside of the wafer to improve the contact resistance. This may help reduce measurement noise at lower voltages. Under the same electric field strength, the addition of molecular iodine to the hydrofluorocarbon increases the measured current through the polymer and lowers the breakdown voltage. The conductivity of C4H2F6 with additives is increased compared to that of C4H2F6 without additives. See the current difference in Figures 1-3. As shown in Table 1, the conductivity was calculated at an electric field of 0.2 MV / cm, and the increase in conductivity at an electric field of 0.2 MV / cm was >10%.

[0095] [Table 3]

[0096] Example 2: ONON hole pattern etching using CH3I as an additive CH3I has shown promising performance on flat thin films (higher selectivity and polyimide over aC masks). It has been added to etch recipes containing C4H2F6 for etching ONON (i.e., alternating layers of SiO / SiN) hole patterns on patterned wafers or substrates for the purpose of increasing the polymer conductivity. The patterned wafer has an ONON layer on top of which is deposited a hole-patterned amorphous carbon (aC) mask layer. The etch recipe may also contain O2.

[0097] Four conditions were tested for preliminary screening: C4H2F6 / CH3I flow rates of 30 / 10sccm, 35 / 5sccm, 40 / 5sccm, and 40 / 10sccm. 30 / 10sccm and 35 / 5sccm have the same total gas flow rates. Because CH3I is highly polymerizable, etch stop was observed in SEM images when the CH3I flow rate was 10sccm or higher. Although the 40 / 5sccm condition showed an improvement in etch selectivity, further adjustment of the etch recipe is required. SEM conditions are as in the flow. Accel. voltage: 5.0kV; Emission current: 20μA; Magnification: ×30.0k.

[0098] CH3I is highly polymerizable and can clog the patterned mask layer and can even cause etch stop at flow rates above 10 sccm added to the ONON etch composition. Adding CH3I to the etch recipe shifts the process window for O2 flow from 68 sccm to 74-76 sccm. For the optimized CH3I recipe: ONON etch rate (ER): 510 nm / min (without CH3I, measured ONON ER is 516 nm / min); ONON / aC selectivity: 11.2-12 (without CH3I, ONON / aC selectivity is 11.4-12). Figures 4-9 are comparisons of ER, selectivity, sidewall bowing, ellipticity, and critical dimension (CD) with different bias powers for C4H2F6 with and without additive CH3I, respectively. Overall, the recipe with CH3I shows less dependence on bias power (ONON etch rate, selectivity, bowing, ellipticity, profile CD) compared to the recipe without CH3I.

[0099] More specifically, as shown in Figure 6, at a bias power of 7000W, the addition of CH3I to the recipe did not show any significant change in the ellipticity of the aC mask holes, with the measured ellipticity being 93% for the recipe without CH3I and 94% for the recipe with CH3I. At a bias power of 5600W, the recipe without CH3I showed a degradation of the aC mask profile with decreasing bias power, while the recipe with CH3I showed less impact. At a bias power of 4200W, the recipe with CH3I showed an improvement in the etch performance, including ER, selectivity, aC mask ellipticity, and tilt angle. The etch performance is summarized in Table 2.

[0100] [Table 4]

[0101] In summary, the additive CH3I improves the surface passivation (aka polymer layer) on the etch front and sidewalls of HAR features, and the passivation changes with the variation of plasma etch conditions (RF power, process time, etc.). Furthermore, the addition of CH3I as an additive to hydrofluorocarbon etch gases reduces the bias power by 40% without compromising etch performance such as etch rate, selectivity, ellipticity, and profile CD.

[0102] Example 3: Chemical composition of polymers and electrical conductivity of polymers Substrate: To obtain the I-V characteristics of the polymer only, low resistivity Si substrates (<0.02 Ω·cm) were used for polymer deposition instead of SiO2 substrates. The Si substrates were cut into 1 inch × 1 inch coupons to facilitate I-V measurements using a mercury probe.

[0103] Polymer deposition: The same deposition process conditions were used for C4F8, C4H2F6, C4F9I, C4F8 + C4F9I, and C4H2F6 + C4F9I; the thickness of the deposited polymer was measured with an ellipsometer; for the polymer on the ion block region, the thickness was measured at a position 1 mm away from the edge of the shield coupon.

[0104] Ramm tool experimental conditions: RF source power: 750 W; bias power: 1500 W; Ar / etching gas (or gas mixture) / O2: 250 / 15 / 0; etching time: 30 seconds.

[0105] Figure 10 shows various polymer chemical compositions and the electrical conductivity of the polymers. The measured values of current (I) ~ voltage (V) were the same as those in Example 1. As shown, under the same electric field strength, the addition of iodine molecule additives to hydrofluorocarbons induces a higher measured current and a lower breakdown voltage through the polymer. The conductivities at 0.2 MV / cm for various polymers and iodine molecule additives are as follows: C4F9I > C4H2F6 + C4F9I > C4F8 + C4F9I > C4H2F6 > C4F8. The higher the C - C:C - Fx / C - I ratio of the polymer, the higher the breakdown voltage and the higher the electrical strength. It is considered that the C - F bond contributes to the conductivity of the polymer. Polymers containing more C - C bonds have lower conductivity than polymers containing more C - F x bonds. x

[0106] Table 3 shows the bond concentration ratio of C - C:C - F x / C - I (x is an integer). The bond concentration ratio of C - C:C - F x / C - I is C4F9I < C4F8 + C4F9I < C4F8 < C4H2F6 + C4F9I < C4H2F6 from low to high. The C - C bond is a non - polar covalent bond; the C - Fx / C - I bond is a polar covalent bond. The conductivity was calculated at an electric field of 0.2 MV / cm, and the increase in conductivity at an electric field of 0.2 MV / cm was >10%.

[0107]

Table 5

[0108] Because of the different conduction mechanisms in various electric fields, it is difficult to show how the chemical composition of the polymer and its electrical conductivity are related to each other, but in general, the addition of iodine to the polymer makes it more conductive, which results in at least about 10% lower bias power compared to the case without the additive, or even the elimination of the bias power, without compromising etch performance such as etch rate, selectivity, ellipticity, and profile CD, as shown in Example 2.

[0109] It will be understood that many additional changes in the details, materials, steps, and arrangements of parts described and illustrated herein to explain the nature of the invention may be made by those skilled in the art within the principles and scope of the invention as set forth in the appended claims. Accordingly, it is not intended that the invention be limited to the specific embodiments in the examples given above and / or in the accompanying drawings.

[0110] Although embodiments of the present invention have been shown and described, they may be modified by those skilled in the art without departing from the spirit and teachings of the present invention. The embodiments described herein are merely exemplary and not limiting. Many variations and modifications of the compositions and methods are possible and are within the scope of the present invention. Thus, the scope of protection is not limited to the embodiments described herein, but only by the claims, including all equivalents of the subject matter of the claims.

Claims

1. 1. A method for forming a high aspect ratio (HAR) patterned structure on a substrate in a reaction chamber during a HAR etching process, comprising: Hydrofluorocarbon or fluorocarbon compounds and SiH ２ I ２ sequentially or simultaneously exposing the substrate to vapor of an etchant comprising: The plasma is activated to produce a mixture of an activated hydrofluorocarbon or fluorocarbon compound and an activated SiH ２ I ２ and the film not covered by the patterned mask layer, the activated hydrofluorocarbon or fluorocarbon compound, and the activated SiH ２ I ２ and selectively etching the film from the patterned mask layer, thereby forming the HAR patterned structure; Including, A highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structure.

2. The method further includes the step of introducing an oxidizing agent into the reaction chamber, the oxidizing agent being O ２ , O ３ , CO, CO ２ , NO, N ２ O, NO ２ , H ２ O, H ２ O ２ , COS, SO ２ and combinations thereof.

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

4. The activated hydrofluorocarbon or fluorocarbon compound and the activated SiH ２ I ２ and the conductivity of the highly conductive sidewall passivation layer formed using the activated SiH ２ I ２ 2. The method of claim 1, wherein the conductivity of the highly conductive sidewall passivation layer is at least 10% higher than that of the highly conductive sidewall passivation layer formed using the activated hydrofluorocarbon or fluorocarbon compound without the addition of

5. The hydrofluorocarbon or fluorocarbon compound is CF ４ , C.H. ３ F.C. ２ F ６ , C ３ F ８ , C ２ H.F. ５ , C ５ F ８ , C ６ F ６ , C ４ F ６ , C ４ F ８ , C １ ~C ５ Saturated or unsaturated linear, branched or cyclic hydrofluorocarbons, such as C ４ H ２ F ６ , C.H.F. ３ , C.H. ２ F ２ or a combination thereof.

6. The hydrofluorocarbon or fluorocarbon compound is ４ H ２ F ６ The method of claim 1, wherein

7. 10. The method of claim 1, wherein the film is a silicon-containing film comprising O and / or N and containing dopants such as B, C, P, As, Ga, In, Sn, Sb, Bi, and / or Ge, and combinations thereof.

8. 2. The method of claim 1, wherein the patterned mask layer is an a-C layer, a doped a-C layer, a photoresist layer, an anti-reflective layer, an organic planarization layer, a poly-Si layer, a metal oxide layer, such as oxides of Ti, Al, Zr, Hf, and combinations thereof.

9. The method of claim 1 , wherein the HAR patterned structures formed in the film have an aspect ratio of 1:1 to 200:

1.

10. and introducing an additional etching gas into the reaction chamber, the additional etching gas being cC ４ F ８ , C ４ F ８ , cC ５ F ８ , C ５ F ８ , C ４ F ６ , C.F. ４ , C.H. ３ F, C.F. ３ H, C.H. ２ F ２ , C ３ H.F. ７ , C ３ F ６ , C ３ H ２ F ６ , C ３ H ２ F ４ , C ３ H ３ F ５ , C ４ H.F. ７ , C ５ H.F. ９ , C ３ F ６ , C ３ F ８ , C.F. ３ I.C. ２ F ３ I.C. ２ F ５ I.C. ３ F ７ I, 1-iodoheptafluoropropane (1-C ３ F ７ I), 2-iodoheptafluoropropane (2-C ３ F ７ I), C ３ H.F. ７ , COS, FNO, FC≡N, CS ２ , S.O. ２ , S.F. ６ , trans-1,1,1,4,4,4-hexafluoro-2-butene (trans-C ４ H ２ F ６ ), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C ４ H ２ F ６ ), hexafluoroisobutene (C ４ H ２ F ６ ), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C ４ H ２ F ６ ), 1,1,2,2,3-pentafluorocyclobutane (C ４ H ３ F ５ ), 1,1,2,2-tetrafluorocyclobutane (C ４ H ４ F ４ ), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C ４ H ２ F ６ 10. The method of claim 1, wherein the compound is selected from the group consisting of:

11. 1. A method for forming a HAR patterned structure, comprising: The substrate is cooled in the reaction chamber. ４ H ２ F ６ and SiH ２ I ２ wherein the substrate has a film disposed thereon and a patterned mask layer disposed on the film; Activating the plasma to produce activated C ４ H ２ F ６ and activated SiH ２ I ２ and the film not covered by the patterned mask layer, and the activated C ４ H ２ F ６ and the SiH ２ I ２ to selectively etch the film from the patterned mask layer, thereby forming the HAR patterned structure; Including, A highly conductive sidewall passivation layer is formed on the sidewalls of the HAR patterned structure.

12. The method further includes the step of introducing an oxidizing agent into the reaction chamber, the oxidizing agent being O ２ , O ３ , CO, CO ２ , NO, N ２ O, NO ２ , H ２ O, H ２ O ２ , COS, SO ２ and combinations thereof.

13. The method further includes the step of introducing an inert gas into the reaction chamber, the inert gas being selected from the group consisting of He, Ar, Xe, Kr, Ne, and N. ２ The method of claim 11 , selected from the group consisting of:

14. The activated C ４ H ２ F ６ and the activated SiH ２ I ２ The conductivity of the highly conductive sidewall passivation layer formed using the activated SiH ２ I ２ The activated C ４ H ２ F ６ 12. The method of claim 11, wherein the conductivity of the highly conductive sidewall passivation layer is at least 10% higher than that of the highly conductive sidewall passivation layer formed using

15. The method of claim 11, wherein the HAR patterned structures formed in the film have an aspect ratio of 1:1 to 200:

1.

16. and introducing an additional etching gas into the reaction chamber, the additional etching gas being cC ４ F ８ , C ４ F ８ , cC ５ F ８ , C ５ F ８ , C ４ F ６ , C.F. ４ , C.H. ３ F, C.F. ３ H, C.H. ２ F ２ , C ３ H.F. ７ , C ３ F ６ , C ３ H ２ F ６ , C ３ H ２ F ４ , C ３ H ３ F ５ , C ４ H.F. ７ , C ５ H.F. ９ , C ３ F ６ , C ３ F ８ , C.F. ３ I.C. ２ F ３ I.C. ２ F ５ I.C. ３ F ７ I, 1-iodoheptafluoropropane (1-C ３ F ７ I), 2 -Iodoheptafluoropropane (2-C ３ F ７ I), C ３ H.F. ７ , COS, FNO, FC≡N, CS ２ , S.O. ２ , S.F. ６ , trans-1,1,1,4,4,4-hexafluoro-2-butene (trans-C ４ H ２ F ６ ), cis-1,1,1,4,4,4-hexafluoro-2-butene (cis-C ４ H ２ F ６ ), hexafluoroisobutene (C ４ H ２ F ６ ), trans-1,1,2,2,3,4-hexafluorocyclobutane (trans-C ４ H ２ F ６ ), 1,1,2,2,3-pentafluorocyclobutane (C ４ H ３ F ５ ), 1,1,2,2-tetrafluorocyclobutane (C ４ H ４ F ４ ), and cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C ４ H ２ F ６ 12. The method of claim 11 , wherein the compound is selected from the group consisting of:

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