Nitrogen compounds used for etching semiconductor structures

Abstract

A method for etching a silicon-containing film is disclosed. The method includes the following steps: introducing a vapor of a nitrogen-containing etching compound into a reaction chamber containing a silicon-containing film on a substrate, wherein the nitrogen-containing etching compound is an organofluorine compound containing at least one C≡N or C=N functional group; introducing an inert gas into the reaction chamber; and activating a plasma to generate an activated nitrogen-containing etching compound capable of etching the silicon-containing film from the substrate.

Description

[0001] This application is a divisional application of Chinese invention patent application entitled "Nitrogen-containing compound for etching semiconductor structures", filed on August 30, 2016, with application number 201680048436.5 and international application number PCT / US2016 / 049479.

[0002] Cross-references to related applications

[0003] This application claims the benefit of U.S. Application Serial No. 14 / 841,271, filed August 31, 2015, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0004] A method for etching a silicon-containing film is disclosed. The method includes the following steps: introducing a vapor of a nitrogen-containing etching compound into a reaction chamber containing a silicon-containing film on a substrate, wherein the nitrogen-containing etching compound is an organofluorine compound containing at least one C≡N or C=N functional group; introducing an inert gas into the reaction chamber; and activating a plasma to generate an activated nitrogen-containing etching compound capable of etching the silicon-containing film from the substrate. Background Technology

[0005] In memory applications within the semiconductor industry, such as DRAM and 2D NAND, plasma etching removes silicon-containing films, such as SiO or SiN layers, from the semiconductor substrate. For 3D NAND (e.g., see US 2011 / 0180941 awarded to Samsung Electronics Co., Ltd.), etching a stack of multiple SiO / SiN or SiO / polysilicon (p-Si) layers is critical. A highly selective etchant between the mask and the layer being etched is essential. Furthermore, the etched structure should have a straight, vertical profile without bends and a low LER (line etch roughness).

[0006] Conventional etching gases include octafluorocyclobutane (cC4F8), hexafluoro-1,3-butadiene (C4F6), CF4, CH2F2, CH3F, and / or CHF3. It is well known that selectivity and polymer deposition rate increase with increasing C:F ratio (i.e., C4F6 > C4F8 > CF4). See, for example, US6387287 granted to Hung et al.

[0007] However, conventional etching chemistry processes may not be able to provide aspect ratios higher than 20:1 (which are necessary in newer applications such as 3D NAND) due to insufficient etch-resistant polymer deposition on the sidewalls, at least due to inadequate etch-resistant polymer deposition during plasma etching processes. x Fy - The polymer may be easily etched, where x is in the range of 0.01 to 1 and y is in the range of 0.01 to 4. As a result, the etched pattern may not be perpendicular, and the etched structure may exhibit bending, dimensional changes, pattern collapse, and / or increased roughness.

[0008] Bending may be caused by the etching of the sidewalls of the mask layer, which is often an amorphous carbon (aC) material. The aC material may be etched by oxygen radicals in the plasma, which may cause an increase in the mask opening and result in a bent, or angular / curved etched structure.

[0009] Ji et al. (US 5,814,563) disclosed the use of mixtures of fluorinated hydrocarbons, carbon-oxygen compounds, and gases that generate NH3 to achieve high selectivity of dielectrics (such as SiO and SiN) for p-Si layers. Shane (US 2003 / 0162395) disclosed the addition of nitrogen-containing gases to fluorocarbon compounds to deposit polymers onto a mask to improve selectivity while etching silicon dioxide layers. Nemani et al. (US 2014 / 0199851) disclosed the use of plasma processes (by flowing NF3 and NH3 to remove modified portions of silicon nitride layers) to pattern silicon nitride dielectric films. Hamrah et al. (US 5,242,538) disclosed the use of CF4 and NH3 etching gases and observed silicon oxide selectivity up to 100:1 compared to polycrystalline silicon selectivity. Pu et al. (US 5,843,847) also disclosed the addition of additional nitrogen to fluorinated etching gases to aid in feature size control.

[0010] Nitrogen-containing compounds have been used as etching gases. For example, Khandelwal et al. (“Dry removal technology for advanced CMOS devices”, Nanochip Tech.J., Vol. 11, No. 2, 2013, pp. 17-19) disclosed an in-situ dry removal process using NH4F as an etchant. Garg et al. (US 2006 / 0062914) disclosed activated reactive gases for processing substrate surfaces. In paragraph

[0019] , Garg et al. described that the activated reactive gases could include a wide variety of fluorinated gases, including C3F3N3, fluorinated amines such as CF5N, fluoronitriles such as C2F3N, C3F6N, and CF3NO. Felker et al. (US 6,508,948) disclosed perfluorinated heteroaromatic amine etching compounds, including cyanuric fluoride compounds. One disclosed cyanuric fluoride compound is pentafluoropyridine C5F5N.

[0011] It is important to minimize bending and achieve the high aspect ratios (i.e., up to 200:1) required for current applications (e.g., contact etching or 3D NAND). Furthermore, current etching is not limited by the selectivity of photoresist masks. Equally important are the use of other materials such as aC, SiN, p-Si, SiC, or other forms of Si. a C b O c H d N e High selectivity is achieved among materials (where a>0; b, c, d, and e≥0).

[0012] Therefore, there is still a need for new etching gas compositions for plasma etching applications that can maintain selectivity for a wide range of process conditions and a high aspect ratio. Summary of the Invention

[0013] Methods for plasma etching of silicon-containing films are disclosed. These methods include the steps of: introducing a vapor of a nitrogen-containing etching compound into a reaction chamber containing a silicon-containing film on a substrate, wherein the nitrogen-containing etching compound comprises an organofluorine compound containing C≡N or C=N functional groups; introducing an inert gas into the reaction chamber; and activating the plasma to generate an activated nitrogen-containing etching compound capable of etching the silicon-containing film from the substrate. The disclosed methods may include one or more of the following aspects:

[0014] This organofluorine compound contains a C≡N functional group;

[0015] This organofluorine compound has the formula N≡CR 1 , where R 1 Having the formula H a F b C c And a = 1 - 11, b = 1 - 11, and c = 1 - 5;

[0016] This organofluorine compound has the formula... difluoroacetonitrile (C2HF2N);

[0017] This organofluorine compound has the formula... 2,3,3,3-Tetrafluoropropionitrile (C3HF4N);

[0018] This organofluorine compound has the formula... 2,2,3,3-Tetrafluoropropionitrile (C3HF4N);

[0019] This organofluorine compound has the formula... 4,4,4-trifluorocrotonitrile (C4H2F3N);

[0020] This organofluorine compound has the formula... 3,3,3-trifluoropropionitrile (C3H2F3N);

[0021] This organofluorine compound has the formula... Fluoroacetonitrile (C2H2FN);

[0022] This organofluorine compound has the formula (N≡C-)-(R 2 )-(-C≡N), where R 2 Independently possessing the formula H a F b C c , where a = 0, b = 1 - 11, and c = 1 - 5;

[0023] This organofluorine compound has the formula... Octafluorohexane-1,6-dionitrile (C6F8N2);

[0024] This organofluorine compound has the formula... 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene (C6F6N2);

[0025] This organofluorine compound has the formula (N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 1 - 11, b = 1 - 11, and c = 1 - 5;

[0026] This organofluorine compound has the formula... 2-[1-(difluoromethyl)-2,2,2-trifluoroethylene]-malononitrile (C6HF5N2)

[0027] This organofluorine compound contains a C=N functional group;

[0028] The organofluorine compound has the formula R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, x + z = 1 - 3, and each R 1 and R 2 Independently possessing the formula H a F b C c , where a = 0, b = 1 - 11, and c = 0 - 5;

[0029] This organofluorine compound has the formula... N,1,1,1,3,3,3-heptafluoropropylamine (C3F7N);

[0030] The organofluorine compound has the formula R 1 x [-C=N(R 3 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, x + z = 1 - 3, and each R 1 and R 3 Independently possessing the formula H a F b C c , where a = 1 - 11, b = 0 - 11, and c = 0 - 5;

[0031] This organofluorine compound has the formula... Hexafluoroacetone imine (C3HF6N);

[0032] This organofluorine compound has the formula... 1,1,1,6,6,6-hexafluoro-3-azahexane-3-ene (C5H5F6N);

[0033] • The activated nitrogen-containing etching compound reacts with the silicon-containing film to form volatile byproducts;

[0034] • Remove these volatile byproducts from the reaction chamber;

[0035] The inert gas was selected from the group consisting of He, Ar, Xe, Kr, and Ne;

[0036] The inert gas is Ar;

[0037] • The vapor of the nitrogen-containing etching compound and the inert gas are mixed to produce a mixture before being introduced into the reaction chamber;

[0038] • The vapor of the nitrogen-containing etching compound is introduced into the reaction chamber separately from the inert gas;

[0039] • The inert gas is continuously introduced into the reaction chamber, and the vapor of the nitrogen-containing etching compound is introduced into the reaction chamber in a pulsed manner;

[0040] The inert gas accounts for approximately 0.01% v / v to approximately 99.9% v / v of the total volume of the vapor and inert gas of the nitrogen-containing etching compound introduced into the reaction chamber;

[0041] The inert gas accounts for approximately 90% v / v to approximately 99% v / v of the total volume of the vapor and inert gas of the nitrogen-containing etching compound introduced into the reaction chamber;

[0042] • Introduce the oxidant into the reaction chamber;

[0043] • Do not introduce oxidizing agents into this reaction chamber;

[0044] The oxidant is selected from the group consisting of O2, CO, CO2, NO, N2O, and NO2;

[0045] The oxidizing agent is O2;

[0046] • The vapor of the nitrogen-containing etching compound and the oxidant are mixed before being introduced into the reaction chamber;

[0047] • The vapor of the nitrogen-containing etching compound is introduced into the reaction chamber separately from the oxidant;

[0048] • The oxidant is continuously introduced into the reaction chamber and the vapor of the nitrogen-containing etching compound is introduced into the reaction chamber in a pulsed manner;

[0049] The oxidant accounts for approximately 0.01% v / v to approximately 99.9% v / v of the total volume of the vapor and oxidant of the nitrogen-containing etching compound introduced into the reaction chamber;

[0050] The oxidant accounts for approximately 0.01% v / v to approximately 10% v / v of the total volume of the vapor and oxidant of the nitrogen-containing etching compound introduced into the reaction chamber;

[0051] The silicon-containing film comprises layers of the following: silicon oxide, silicon nitride, polycrystalline silicon, crystalline silicon, SiON, SiOCH, and Si. a O b C c N d H e (where a>0; b, c, d, and e≥0) or combinations thereof;

[0052] The silicon-containing film contains oxygen atoms, nitrogen atoms, carbon atoms, hydrogen atoms, or combinations thereof;

[0053] • This silicon-containing film contains silicon carbide;

[0054] • The silicon-containing film was selectively etched from the aC layer;

[0055] • The silicon-containing film was selectively etched from the photoresist layer;

[0056] • The silicon-containing film is selectively etched from the silicon nitride layer;

[0057] • The silicon-containing film is selectively etched from the polycrystalline silicon layer;

[0058] • The silicon-containing film is selectively etched from the crystalline silicon layer;

[0059] • The silicon-containing film was selectively etched from the metal contact layer;

[0060] • The silicon-containing film was selectively etched from the titanium nitride layer;

[0061] • The silicon-containing film was selectively etched from the tantalum layer;

[0062] • The silicon-containing film is a silicon oxide layer;

[0063] • Selectively etch the silicon oxide layer from the aC layer;

[0064] • Selectively etch the silicon oxide layer from the photoresist layer;

[0065] • Selectively etch the silicon oxide layer from the p-Si layer;

[0066] • Selectively etch the silicon oxide layer from the crystalline silicon layer;

[0067] • Selectively etch the silicon oxide layer from the metal contact layer;

[0068] • Selectively etch the silicon oxide layer from the SiN layer;

[0069] • The silicon-containing film is a silicon nitride layer;

[0070] • Selectively etch the silicon nitride layer from the aC layer;

[0071] • Selectively etch the silicon nitride layer from the patterned photoresist layer;

[0072] • Selectively etch the silicon nitride layer from the p-Si layer;

[0073] • Selectively etch the silicon nitride layer from the crystalline silicon layer;

[0074] • Selectively etch the silicon nitride layer from the metal contact layer;

[0075] • Selectively etch the silicon nitride layer from the silicon oxide layer;

[0076] • The silicon-containing film is a SiON layer;

[0077] • Selectively etch the SiON layer from the photoresist layer;

[0078] • The silicon-containing film is a SiCOH layer;

[0079] • Selectively etch the SiCOH layer from the titanium nitride layer;

[0080] • Selectively etch the SiCOH layer from the aC layer;

[0081] • Selectively etch the SiCOH layer from the photoresist layer;

[0082] • The silicon-containing film consists of alternating layers of silicon oxide and silicon nitride;

[0083] • Etch both the silicon oxide and silicon nitride layers at similar etching rates;

[0084] • Selectively etch both the silicon oxide and silicon nitride layers from the silicon layer;

[0085] • Selectively etch both the silicon oxide and silicon nitride layers from the p-Si layer;

[0086] • Selectively etch both the silicon oxide and silicon nitride layers from the crystalline silicon layer;

[0087] • Selectively etch both the silicon oxide and silicon nitride layers from the aC layer;

[0088] • The silicon-containing film consists of alternating layers of silicon oxide and p-Si;

[0089] • Etch both the silicon oxide and p-Si layers at similar etching rates;

[0090] • Selectively etch both the silicon oxide and p-Si layers from the aC layer;

[0091] • Selectively etch both the silicon oxide and p-Si layers from the silicon nitride layer;

[0092] • An aperture with an aspect ratio between approximately 10:1 and approximately 200:1 is formed in the silicon-containing film;

[0093] • Create gate trenches;

[0094] • Generates stepped contacts;

[0095] • Create a channel hole;

[0096] • Creates channel holes with an aspect ratio between approximately 60:1 and approximately 100:1;

[0097] • To generate channel pores with diameters ranging from approximately 5 nm to approximately 100 nm;

[0098] • To generate channel holes with diameters ranging from approximately 10 nm to approximately 50 nm;

[0099] • Improve selectivity by introducing etching gas into the reaction chamber;

[0100] The etching gas is selected from the following group, which consists of the following items: cC4F8, C4F8, C4F6, CF4, CH3F, CF3H, CH2F2, COS, CF3I, C2F3I, C2F5I, FC≡N, CS2, SO2, 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), or cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6);

[0101] The etching gas is cC5F8;

[0102] The etching gas is cC4F8;

[0103] The etching gas is C4F6;

[0104] • The vapor of the nitrogen-containing etching compound and the etching gas are mixed before being introduced into the reaction chamber;

[0105] • The vapor of the nitrogen-containing etching compound is introduced into the reaction chamber separately from the etching gas;

[0106] • Introduce the etching gas at a concentration of approximately 0.01% v / v to approximately 99.99% v / v into the reaction chamber;

[0107] • The plasma is activated by applying RF power;

[0108] • The plasma was activated by RF power ranging from approximately 25 W to approximately 10,000 W;

[0109] The reaction chamber has a pressure ranging from approximately 1 millitor to approximately 10 tors.

[0110] • The vapor of the nitrogen-containing etching compound is introduced into the reaction chamber at a flow rate ranging from approximately 0.1 sccm to approximately 1 slm;

[0111] • Maintain the substrate at a temperature ranging from approximately -196°C to approximately 500°C;

[0112] • Maintain the substrate at a temperature ranging from approximately -120°C to approximately 300°C;

[0113] • Maintain the substrate at a temperature ranging from approximately -100°C to approximately 50°C;

[0114] • Maintain the substrate at a temperature ranging from approximately -10°C to approximately 40°C; and

[0115] • The activated nitrogen-containing etched compound was measured using a quadrupole mass spectrometer, optical emission spectrometer, FTIR, or other radical / ion measurement tools.

[0116] It also discloses nitrogen-containing etching compounds comprising organofluorine compounds having C≡N or C=N functional groups. The disclosed nitrogen-containing etching compounds include one or more of the following:

[0117] This organofluorine compound contains a C≡N functional group;

[0118] This organofluorine compound has the formula N≡C–R 1 , where R 1 Having the formula H a F b C c And a = 1 - 11, b = 1 - 11, and c = 1 - 5;

[0119] This organofluorine compound has the formula... difluoroacetonitrile (C2HF2N);

[0120] This organofluorine compound has the formula... 2,3,3,3-Tetrafluoropropionitrile (C3HF4N);

[0121] This organofluorine compound has the formula... 2,2,3,3-Tetrafluoropropionitrile (C3HF4N);

[0122] This organofluorine compound has the formula... 4,4,4-trifluorocrotonitrile (C4H2F3N);

[0123] This organofluorine compound has the formula... 3,3,3-trifluoropropionitrile (C3H2F3N);

[0124] This organofluorine compound has the formula... Fluoroacetonitrile (C2H2FN);

[0125] This organofluorine compound has the formula (N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 0, b = 1 - 11, and c = 1 - 5;

[0126] This organofluorine compound has the formula... Octafluorohexane-1,6-dionitrile (C6F8N2);

[0127] This organofluorine compound has the formula... 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene (C6F6N2);

[0128] This organofluorine compound has the formula (N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 1 - 11, b = 1 - 11, and c = 1 - 5;

[0129] This organofluorine compound has the formula... 2-[1-(difluoromethyl)-2,2,2-trifluoroethylene]-malononitrile (C6HF5N2)

[0130] This organofluorine compound contains a C=N functional group;

[0131] The organofluorine compound has the formula R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, x + z = 1 - 3, and each R 1 and R 2 Independently possessing the formula H a F b C c , where a = 0, b = 0 - 11, and c = 0 - 5;

[0132] This organofluorine compound has the formula... N,1,1,1,3,3,3-heptafluoropropylamine (C3F7N);

[0133] The organofluorine compound has the formula R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, x + z = 1 - 3, and each R 1 and R 2 Independently possessing the formula H a F b C c , where a = 1 - 11, b = 0 - 11, and c = 0 - 5;

[0134] This organofluorine compound has the formula... Hexafluoroacetone imine (C3HF6N);

[0135] This organofluorine compound has the formula... 1,1,1,6,6,6-hexafluoro-3-azahexane-3-ene (C5H5F6N);

[0136] • It has a purity ranging from about 95% to about 99.999% by volume;

[0137] • Contains trace gaseous impurities ranging from approximately 10 to approximately 5% by volume;

[0138] These trace gaseous impurities include water;

[0139] These trace gaseous impurities include CO2;

[0140] These trace gaseous impurities include N2; and

[0141] The nitrogen-containing etching compound has a water content of less than 20 ppmw.

[0142] Tagging and naming

[0143] The following detailed description and claims utilize many abbreviations, symbols, and terms commonly known in the art. While definitions are typically provided with the first example of each acronym, for convenience, Table 1 provides a list of the abbreviations, symbols, and terms used, along with their respective definitions.

[0144] Table 1

[0145]

[0146]

[0147] As used herein, the term "etch" refers to a plasma etching process (i.e., a dry etching process) in which ion bombardment accelerates a chemical reaction in the vertical direction, resulting in the formation of vertical sidewalls perpendicular to the substrate along the edges of the masking feature (Manos and Flamm, *Plasma Etching: An Introduction*, Academic Press, Inc., 1989, pp. 12-13). This etching process creates holes in the substrate, such as through-holes, trenches, channel vias, gate trenches, stepped contacts, capacitor vias, contact vias, etc.

[0148] The term “patterned etching” or “patterned etching” refers to etching non-planar structures, such as patterned mask layers on a stack of silicon films.

[0149] The term "mask" refers to a layer that resists etching. This mask layer can be placed on top of the layer to be etched.

[0150] The term "etch stop" refers to a layer that protects the underlying layer below the layer being etched.

[0151] The term "device channel" refers to a layer that is part of the actual device, and any damage to it will affect device performance.

[0152] The term "aspect ratio" refers to the ratio of the height of a groove (or the width of a through hole) to the diameter of the through hole.

[0153] The term "selectivity" refers to the ratio of the etching rate of one material to the etching rate of another material. The terms "selective etch" or "selectively etch" mean that more of one material is etched than another, or in other words, that there is an etching selectivity greater than or less than 1:1 between the two materials.

[0154] When used in the context of describing an R group, the term "independently" should be understood to mean that the object R group is chosen independently not only relative to other R groups with the same or different subscripts or superscripts, but also independently relative to any additional kind of the same R group. For example, in the formula MR 1 x (NR 2 R 3 ) (4-x) In the context, M represents an atom, x is 2 or 3, and there are two or three R atoms. 1 Groups can, but do not have to, be the same as each other or with R. 2 Or with R 3 Similarly. Furthermore, it should be understood that, unless otherwise explicitly stated, the values ​​of the R groups are independent of each other when used in different formulas.

[0155] Note that the terms "film" and "layer" are used interchangeably herein. It should be understood that a film may correspond to or be associated with a layer, and the layer may refer to the film. Furthermore, those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to the thickness of some material laid or spread on a surface, and that surface can range from as large as an entire wafer to as small as a trench or line.

[0156] Note that the terms "etching compound" and "etching gas" are used interchangeably here. It should be understood that an etching compound may correspond to or be associated with an etching gas, and the etching gas may refer to the etching compound.

[0157] 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 planar substrate; and the abbreviation “3D” refers to a three-dimensional or vertical gate structure in which gate structures are stacked in a vertical direction.

[0158] The standard abbreviations of the elements from the periodic table are used here. It should be understood that elements may be referred to by these abbreviations (e.g., Si for silicon, N for nitrogen, O for oxygen, C for carbon, H for hydrogen, F for fluorine, etc.).

[0159] A unique CAS registry number (i.e., "CAS") assigned by the Chemical Abstracts Service is provided to help better identify the disclosed molecules.

[0160] Please note that silicon-containing films, such as SiN and SiO, are listed throughout this specification and claims without mentioning their proper stoichiometry. These silicon-containing films may include pure silicon (Si) layers, such as crystalline Si, polycrystalline silicon (p-Si or polycrystalline Si), or amorphous silicon; silicon nitride (SiO2)... k N l ) layer; or silicon dioxide (Si) n O m A layer; or a mixture thereof, wherein k, I, m, and n are in the range of 0.1 to 6 (inclusive). Preferably, silicon nitride is Si. k N l Where k and I are each in the range of 0.5 to 1.5. More preferably, the silicon nitride is Si3N4. Preferably, the silicon oxide is Si. n O m Where n is in the range of 0.5 to 1.5 and m is in the range of 1.5 to 3.5. More preferably, the silicon oxide is SiO2. Here, SiO in the following description can be used to represent Si-containing... n O m The silicon-containing film may also be a silicon oxide-based dielectric material, such as organic-based or silicon oxide-based low-k dielectric materials, such as Applied Materials, Inc.'s Black Diamond II or III materials (with the formula SiOCH). The silicon-containing film may also include Si... a O b N c, where a, b, and c are in the range of 0.1 to 6. These silicon-containing films may also include dopants such as B, C, P, As, and / or Ge. Attached Figure Description

[0161] To further understand the nature and purpose of the present invention, reference should be made to the following detailed description in conjunction with the accompanying drawings, in which similar elements are given the same or similar reference numerals, and wherein:

[0162] Figure 1a This is a cross-sectional side view of an exemplary layer in a 3D NAND stack;

[0163] Figure 1b This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing the polymer deposited on the sidewalls during etching of the 3D NAND stack;

[0164] Figure 1c This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing particles generated during the etching of alternating SiO / SiN layers in a 3D NAND stack;

[0165] Figure 1d This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing selective etching of SiN exposed on the sidewalls of the 3D NAND stack;

[0166] Figure 2 This is a cross-sectional side view of an exemplary layer of a DRAM stack;

[0167] Figure 3a This is a cross-sectional side view of an exemplary layer, showing a photoresist pattern that generates a transistor structure over a SiO insulating layer surrounding a typical transistor device region.

[0168] Figure 3b This was after etching the SiO insulating layer. Figure 3a A cross-sectional side view of an exemplary layer;

[0169] Figure 4 This is a cross-sectional side view of an exemplary reactor system used in exemplary deposition and etching tests;

[0170] Figure 5 This is a graph showing the electron collision ionization energy of C3HF4N compared to the species concentration;

[0171] Figure 6 It is a graph showing the electron collision ionization energy of C2HF2N compared to the species concentration;

[0172] Figure 7 This is an X-ray photoelectron spectrum curve showing the elemental content of the polymer film deposited from C3HF4N;

[0173] Figure 8 It is a graph showing the deposition or etching rate of SiO, SiN, p-Si and aC films using C2HF2N and O2 as a function of oxygen flow rate.

[0174] Figure 9 It is a graph showing the deposition or etching rate of SiO, SiN, p-Si and aC films using C3HF4N and O2 as a function of oxygen flow rate.

[0175] Figure 10 This is a graph showing the etching rate of SiO, SiN, p-Si, and aC films using C3HF4N and CF4 as a function of oxygen flow rate.

[0176] Figure 11 It is a graph comparing the silicon oxide deposition and etching rates of C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 without oxygen addition.

[0177] Figure 12 It is a graph comparing the selectivity of silicon oxide to silicon nitride for C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 without the addition of oxygen.

[0178] Figure 13 It is a graph comparing the silicon oxide etching rates of C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 with 5 sccm of oxygen added.

[0179] Figure 14 It is a graph comparing the selectivity of silicon oxide to silicon nitride for C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 with 5 sccm of oxygen added.

[0180] Figure 15 It is a graph comparing the silicon oxide etching rates of C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 with 10 sccm of oxygen added.

[0181] Figure 16 It is a graph comparing the selectivity of silicon oxide to silicon nitride for C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 with 10 sccm of oxygen added.

[0182] Figure 17It is a graph comparing the silicon oxide etching rates of C3HF4N, C2HF2N, C2F3N, cC4F8, and C4F6 with 15 sccm of oxygen added.

[0183] Figure 18 It is a graph comparing the selectivity of silicon oxide to silicon nitride for C3HF4N, C2HF2N, C2F3N, cC4F8, and C4F6 with 15 sccm of oxygen added.

[0184] Figure 19 This is a graph showing the effect of adding N2 on the etching rate of cC4F8 and O2 on different substrate materials;

[0185] Figure 20 This is a graph showing the effect of adding O2 to cC4F8 and NH3 on the deposition and etching rates of different substrate materials;

[0186] Figure 21 It is a graph showing the electron collision ionization energy of C2F3N compared to the species concentration;

[0187] Figure 22 It is a graph showing the etching rate of SiO, SiN, p-Si and aC films using C2F3N and O2 as a function of oxygen flow rate.

[0188] Figure 23 It is a curve showing the electron collisional ionization data of C3H3F6N compared to the energy; and

[0189] Figure 24 This is a graph showing the deposition and etching rates of C3H3F6N on different substrate materials without the addition of oxygen. Detailed Implementation

[0190] A method for plasma etching semiconductor structures (such as channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, etc.) in silicon-containing films is disclosed. The disclosed method includes the following steps: i) introducing a vapor of a nitrogen-containing etching compound into a reaction chamber containing a silicon-containing film on a substrate, wherein the nitrogen-containing etching compound is an organofluorine compound containing at least one C≡N or C=N functional group; ii) introducing an inert gas into the reaction chamber; and iii) activating the plasma to generate an activated nitrogen-containing etching compound capable of etching the silicon-containing film from the substrate. Here, these organofluorine compounds are organic compounds containing carbon-fluorine (CF) bonds.

[0191] The disclosed organofluorine compounds containing at least one C≡N functional group have the following general formula:

[0192] N≡CR 1(I)

[0193] (N≡C-)(R 2 (-C≡N) (II)

[0194] Where R 1 It has the formula H a F b C c The functional groups, where a = 1 - 11, b = 1 - 11, and c = 0 - 5, and R 2 It has the formula H a F b C c The functional groups are defined as follows: where a = 0-11, b = 1-11, and c = 0-5. This H... a F b C c The functional groups can be linear, branched, or cyclic, and can be saturated or unsaturated. The applicant believes that, with C... x F y Compared to polymers (where x is in the range of 0.01 to 1 and y is in the range of 0.01 to 4), C≡N functionality can provide improved resistance to polymer deposition. When the organofluorine compound includes at least one H, the etching rate of SiN can be increased while maintaining high selectivity for the mask layer.

[0195] The disclosed organofluorine compounds containing at least one C=N functional group have the following general formula:

[0196] R 1 x [-C=N(R 2 z )] y (III)

[0197] Where x = 1 - 2, y = 1 - 2, z = 0 - 1, x + z = 1 - 3, and each R 1 and R 2 Independently possessing the formula H a F b C c Where a = 0-11, b = 0-11, and c = 0-5. This H a F b C c The functional groups can be linear, branched, or cyclic, and can be saturated or unsaturated. The applicant believes that, with C... x F y Compared to polymers (where x is in the range of 0.01 to 1 and y is in the range of 0.01 to 4), C=N functionality can provide improved selectivity between silicon layers. When the organofluorine compound includes at least one H, and preferably when R...2 When it is H, the etching rate of SiN can be increased while maintaining high selectivity for the mask layer.

[0198] The disclosed organofluorine compounds may be hydrofluorocarbons (C≡N or C=N functional groups). x H y F z ) or fluorocarbons (C m F n ), or heterohydrofluorocarbons (C≡N or C=N functional groups) x H y F z ) or heterofluorocarbons (C m F n ), where m, n, x, y, and z are integers.

[0199] The disclosed nitrogen-containing etching compounds include difluoroacetonitrile (C2HF2N), 2,3,3,3-tetrafluoropropionitrile (C3HF4N), 2,2,3,3-tetrafluoropropionitrile (C3HF4N), or hexafluoroacetone imine (C3HF6N), which are listed in Table 2. These molecules are commercially available, and their structural formulas, CAS numbers, and boiling points are also included in Table 2.

[0200] Table 2. Commercially available etching compounds

[0201]

[0202]

[0203]

[0204] The disclosed nitrogen-containing etching compounds may also include 4,4,4-trifluorocrotonitrile (C4H2F3N); 3,3,3-trifluoropropionitrile (C3H2F3N); fluoroacetonitrile (C2H2FN); octafluorohexane-1,6-dianitronitrile (C6F8N2); 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene (C6F6N2); N,1,1,1,3,3,3-heptafluoropropylamine (C3F7N); and 1,1,1,6,6,6-hexafluoro-3-azahexane-3-ene (C5H5F6N). Their structural formulas, CAS numbers, and boiling points or predicted boiling points are also included in Table 2. Those skilled in the art will recognize that synthetic methods for these compounds can be obtained using the provided CAS numbers.

[0205] The disclosed nitrogen-containing etch compounds can provide high selectivity for mask layers, etch-stop layers, and device channel materials without profile distortion in high aspect ratio structures, such as those with aspect ratios ranging from 10:1 to 200:1, such as in DRAM and 3D NAND applications. Alternatively, the disclosed nitrogen-containing etch compounds can also provide high selectivity for mask layers or silicon nitride, such as those with aspect ratios ranging from 1:1 to 50:1, in contact etching applications.

[0206] The disclosed nitrogen-containing etch compounds offer virtually unlimited selectivity for a wide range of etch process conditions. Here, selectivity refers to the ratio of the etch rates of two different layers. For example, the selectivity of a SiO layer compared to an aC layer is the etch rate of SiO divided by the etch rate of the aC layer. The disclosed nitrogen-containing etch compounds can provide improved selectivity between these silicon-containing films and mask materials, less damage to channel regions, and reduced bends in patterned high aspect ratio structures. The disclosed nitrogen-containing etch compounds can also etch through alternating layers of p-Si, SiO, and / or SiN, resulting in a vertical etch profile (i.e., indicating selectivity between alternating layers in the range of 2:1 to 1:2).

[0207] The disclosed nitrogen-containing etching compound is provided with a purity greater than 95% v / v, preferably greater than 99.99% v / v, and more preferably greater than 99.999% v / v. The disclosed nitrogen-containing etching compound contains less than 5% by volume of trace gaseous impurities, wherein less than 150 ppm by volume of impurity gases, such as N2 and / or H2O and / or CO2, are included in the trace gaseous impurities. Preferably, the water content in the plasma etching gas is less than 20 ppmw by weight. The purified product can be produced by distillation and / or by passing the gas or liquid through a suitable adsorbent (such as a 4A molecular sieve).

[0208] The disclosed nitrogen-containing etching compound contains any of its isomers less than 10% v / v, preferably less than 1% v / v, more preferably less than 0.1% v / v, and even more preferably less than 0.01% v / v, which can be purified by distilling gas or liquid to remove the isomers and can provide better process repeatability.

[0209] Alternatively, the disclosed nitrogen-containing etching compound may contain its isomers at a range of 5% v / v to 50% v / v, particularly when such a mixture of isomers provides improved process parameters or if the separation of the target isomer is too difficult or expensive. For example, the disclosed nitrogen-containing etching compound may contain 2,3,3,3-tetrafluoropropionitrile at a range of approximately 50% v / v to approximately 75% v / v and 2,2,3,3-tetrafluoropropionitrile at a range of approximately 25% v / v to approximately 50% v / v. This mixture of isomers can reduce the need for two or more gas lines leading to the reaction chamber.

[0210] Some of the disclosed nitrogen-containing etching compounds are gaseous at room temperature and atmospheric pressure. For non-gaseous (i.e., liquid or solid) compounds, their gaseous form can be produced via conventional vaporization steps, such as direct vaporization or by bubbling with an inert gas (N2, Ar, He). These non-gaseous compounds can be fed as liquids into a vaporizer before being introduced into the reactor, where they are vaporized.

[0211] The disclosed nitrogen-containing etching compounds are suitable for plasma etching semiconductor structures (such as channel vias, gate trenches, stepped contacts, capacitor vias, contact vias, etc.) in these silicon-containing films. The disclosed nitrogen-containing etching compounds are compatible not only with currently available mask materials but also with future generations of mask materials because they cause minimal or no damage to the mask along with the good profile of high aspect ratio structures. In other words, the disclosed nitrogen-containing etching compounds can produce vertical etched patterns with minimal to no bending, pattern collapse, or roughness. To achieve these properties, the disclosed nitrogen-containing etching compounds can deposit an etch-resistant polymer layer during etching to help reduce the direct effects of oxygen and fluorine radicals during the etching process. The disclosed nitrogen-containing etching compounds can also reduce damage to p-Si or crystalline Si channel structures during etching. Preferably, the disclosed nitrogen-containing etching compounds are suitably volatile and stable during the etching process used to deliver them into the reactor / chamber.

[0212] Material compatibility testing is important for determining whether any disclosed nitrogen-containing etching compounds will react with the chamber material and degrade the performance of the chamber for short- or long-term use. Key materials involved in components such as chambers and valves include stainless steel, aluminum, nickel, PCTFE, PVDF, PTFE, and other metals and polymers. Sometimes, these materials are exposed to high temperatures (e.g., above 20°C) and high pressures (e.g., above 1 atm), which can enhance their degradation. Metrological methods may include visual inspection, gravimetric measurements, measurements of nanoscale changes in scanning electron microscopy (SEM), tensile strength, hardness, etc.

[0213] The disclosed nitrogen-containing etching compounds can be used for plasma etching of silicon-containing films on substrates. The disclosed plasma etching method is useful in the fabrication of semiconductor devices, such as NAND or 3D NAND gates, flash or DRAM memories, or transistors, such as FinFETs, bulk complementary metal-oxide-semiconductor (bulk CMOS), and fully depleted silicon-on-insulator (FD-SOI) structures. The disclosed nitrogen-containing etching compounds can be used in other application areas, such as various front-end online (FEOL) and back-end online (BEOL) etching applications. Furthermore, the disclosed nitrogen-containing etching compounds can also be used in 3D through-silicon via (TSV) etching applications to etch Si for interconnecting memory with logic circuitry on the substrate.

[0214] This plasma etching method includes providing a reaction chamber in which a substrate is disposed. The reaction chamber can be any accessory or chamber within a device in which the etching method is performed, such as, and not limited to, reactive ion etching (RIE), capacitively coupled plasma (CCP) with a single or multiple frequency RF sources, inductively coupled plasma (ICP), or a microwave plasma reactor, or other types of etching systems capable of selectively removing a portion of a silicon-containing film or generating active species. Those skilled in the art will recognize that different plasma reaction chamber designs provide different electronic temperature control. Suitable commercially available plasma reaction chambers include, but are not limited to, those marketed under the trademark eMAX. TM Selling Applied Materials' magnetically enhanced reactive ion etchers or under its trademark Flex TM The Lam Research family of dual CCP reactive ion etchers for sale. The RF power in such a plasma reaction chamber can be pulsed to control plasma characteristics and thus further improve etching performance (selectivity and damage).

[0215] Alternatively, plasma-treated reactants can be generated outside the reaction chamber. MKS Instruments A reactive gas generator can be used to treat reactants before they are introduced into the reaction chamber. Operating at 2.45 GHz, 7 kW plasma power, and pressures ranging from approximately 0.5 Torr to approximately 10 Torr, the reactant O2 decomposes into two O radicals. Preferably, a remote plasma can be generated with power ranging from approximately 1 kW to approximately 10 kW, more preferably from approximately 2.5 kW to approximately 7.5 kW.

[0216] The reaction chamber may contain one or more substrates. For example, the reaction chamber may contain 1 to 200 silicon wafers with diameters ranging from 25.4 mm to 450 mm. The substrate may be any substrate suitable for manufacturing semiconductors, photovoltaic materials, flat panel or LCD-TFT devices. Examples of suitable substrates include wafers such as silicon, silicon dioxide, glass, or GaAs wafers. From previous manufacturing steps, the wafer will have multiple films or layers thereon, including silicon-containing films or layers. These layers may be patterned or may not be patterned. Examples of suitable layers include, but are not limited to, silicon (such as amorphous silicon, p-Si, crystalline silicon, any of which may be further p-doped or n-doped with B, C, P, As, and / or Ge), silicon dioxide, silicon nitride, silicon oxide, silicon oxynitride, Si a O b H c C d N e (where a>0; b, c, d, e≥0), mask layer materials (such as amorphous carbon, antireflective coatings, photoresist materials, tungsten, titanium nitride, tantalum nitride, or combinations thereof), etch stop layer materials (such as silicon nitride, polycrystalline silicon, crystalline silicon, silicon carbide, SiCN, or combinations thereof), device channel materials (such as crystalline silicon, epitaxial silicon, doped silicon, Si...). a O b H c C d N e (where a>0; b, c, d, e≥0) or combinations thereof). This silicon oxide layer can form a dielectric material, such as an organic-based or silicon oxide-based low-k dielectric material (e.g., a porous SiCOH film). Exemplary low-k dielectric materials are sold by Applied Materials under the trade names Black Diamond II or III. Alternatively, layers containing tungsten or noble metals (e.g., platinum, palladium, rhodium, or gold) can be used. Furthermore, examples of these silicon-containing films can be Si... a O b H c C d N e (where a>0; b, c, d, e≥0). Throughout this specification and claims, the wafer and any associated layers thereon are referred to as the substrate.

[0217] The following are exemplary embodiments of a substrate on which the disclosed nitrogen-containing etching compound can be applied for etching.

[0218] In one embodiment, the substrate 100 may include a stack of multiple layers, such as Figure 1a As shown in the image. Figure 1a This is a cross-sectional side view of an exemplary layer in a 3D NAND stack that generates 3D NAND gates. Figure 1aIn this configuration, a stack 104 of seven alternating SiO / SiN (i.e., 104a / 104b) layers is located on top of a silicon wafer 102 (i.e., ONON or TCAT technology). Those skilled in the art will recognize that some techniques replace the SiN layer 104a with a p-Si layer (e.g., SiO / p-Si or P-BICS technology). An amorphous carbon (aC) mask layer 106 is located on top of the seven SiO / SiN layers 104. The aC mask layer 106 may contain C and H, as well as other elements such as boron, nitrogen, etc., to improve etch resistance during SiO / SiN layer etching. An antireflective coating 108 is located on top of the aC mask layer 106. A patterned photoresist layer 110 is located on top of the antireflective coating 108. Here, a SiON layer (not shown) may be present between the antireflective coating 108 and the aC mask layer 106 to transfer the pattern in the photoresist layer 110 to the aC layer 106. Those skilled in the art will recognize that, Figure 1a The layer stacking in substrate 100 is provided for illustrative purposes only, and the disclosed nitrogen-containing etching compound can be used to etch other types of layer stacks. Furthermore, those skilled in the art will recognize that the number of alternating SiO / SiN or SiO / p-Si layers 104 in the stack of substrate 100 can vary (i.e., it may include more or fewer than the seven SiO / SiN (104a / 104b) layers depicted).

[0219] Figure 1b This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing the polymer deposited on the sidewalls during etching. The disclosed nitrogen-containing compound can generate fragments suitable for anisotropic etching of the silicon-containing film 104 and deposition of an N-containing polymer passivation layer 212 on the sidewalls of the positively etched structure during plasma processing, such as... Figure 1b As shown in [the image]. Figure 1b and Figure 1a The difference between them is that, in Figure 1b In this embodiment, via 214 is formed in substrate 100 by plasma etching using the disclosed nitrogen-containing etching compounds, which also deposit a polymer passivation layer 212 on the sidewalls of via 214. The polymer passivation layer 212 also provides smoother sidewalls, less bending, and less deformation at the bottom of via 214. However, the polymer passivation layer 212 can be readily removed or cleaned using dry or wet etching chemical processes known in the art.

[0220] Figure 1c This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing particles 316 generated during the etching of alternating SiO / SiN layers in the 3D NAND stack. Figure 1cAs shown, the particles 316 generated on the sidewalls of the alternating SiO / SiN (i.e., 104a / 104b) layers 104 can be minimized by using the disclosed nitrogen-containing compounds. Figure 1c and Figure 1b The difference between them is that, in Figure 1c In the process, the alternating SiO / SiN exposed sidewalls have particles 316 generated during plasma etching. The applicant does not believe that the disclosed nitrogen-containing compounds will produce... Figure 1c Particle 316 is shown in the image.

[0221] Figure 1d This is a cross-sectional side view of an exemplary layer in a 3D NAND stack, showing selective etching of SiN exposed on the sidewalls of the 3D NAND stack after etching. The sidewalls of SiN exposed in stack 100 can be selectively etched in a manner such as... Figure 1d As shown: using the disclosed nitrogen-containing compound to selectively disrupt the Si-N bonds in the SiN layer 104b (compared to the Si-O bonds in the SiO layer 104a), selective sidewall SiN etching 418 is formed on the SiO / SiN layer 104 stack in the via 214. Figure 1d and Figure 1b The difference between them is that, in Figure 1d In this method, selective sidewall SiN etching 418 is formed by selectively etching exposed SiN on alternating SiO / SiN sidewalls using a disclosed nitrogen-containing compound. Typically, selective sidewall SiN etching 418 is performed using a wet etching process with a mixture of phosphoric acid. It is known that replacing wet etching processes with dry plasma etching processes significantly improves the economics of semiconductor device manufacturing processes because wet etching requires moving the substrate to different wet etching equipment. Using the disclosed method, all etching, including selective sidewall SiN etching, can be performed in a single etching equipment, which can reduce the cost of semiconductor manufacturing.

[0222] In an alternative embodiment, the substrate 100 may include a stack of multiple layers thereon, such as Figure 2 As shown in the image. Figure 2 This is a cross-sectional side view of an exemplary layer in a DRAM stack that produces DRAM memory. Figure 2 In this configuration, a four-layer stack is located on top of silicon wafer 102. An aC mask layer 106 is located on top of the large SiO layer 104a. An anti-reflective coating 108 is located on top of the aC mask 106. A patterned photoresist layer 110 is located on top of the anti-reflective coating 108. Here, a SiON layer (not shown) may be present between the anti-reflective coating 108 and the aC mask layer 106 to transfer the pattern in the photoresist layer 110 to the aC layer 106. Those skilled in the art will recognize that... Figure 2 The layer stacks shown are provided for illustrative purposes only, and the disclosed nitrogen-containing etch compound can be used to etch other layer stacks, such as for a stack in which the aC mask layer 106 is replaced with a TiN layer. Furthermore, those skilled in the art will recognize that the number of layers in the stack can vary (i.e., it may include more or fewer layers as depicted).

[0223] Figure 3a This is a cross-sectional side view of an exemplary layer, showing a photoresist pattern that creates a transistor structure on a SiO insulating layer surrounding a typical transistor device region. Figure 3a As shown, substrate 600 may include a stack of four layers surrounding a transistor gate electrode region supported on silicon wafer 602. Figure 3a The transistor region shown includes two doped silicon regions 606 serving as the source and drain. A transistor gate dielectric 614 exists beneath the gate electrode 616. The entire transistor (i.e., the transistor gate dielectric 614 and the gate electrode 616) is surrounded by a thin SiN layer 608, which can later act as an etch stop layer during contact etching. Each transistor device region 616 / 606 is separated by a SiO isolation region 604 in a silicon wafer 602 to minimize electrical interference. Those skilled in the art will recognize that layer 602 can be located on top of a silicon oxide layer on a silicon-on-insulator (SOI) wafer. Another SiO layer 610 is deposited on the transistor and used to insulate the metal contacts from the transistor device region 606. The SiO layer 610 is patterned using a photoresist mask 612. Etching is performed in a plasma environment using the disclosed nitrogen-containing etch compound. Here, the photoresist acts as a mask for etching the SiO layer 610 and stops etching on the SiN layer 608, as shown. Figure 3b As shown in the image.

[0224] Figure 3b This was after etching the SiO insulating layer. Figure 3a A cross-sectional side view of an exemplary layer. Figure 3b and Figure 3a The difference between them is that, in Figure 3b In this process, vias 718 are formed in the SiO layer 610 by etching with a disclosed nitrogen-containing compound. The SiO layer 610 can be etched using a photoresist layer 612 as a mask layer. This mask layer can be any suitable photoresist mask material, such as TiN, aC, etc. The etching can be stopped at the underlying SiN layer 608.

[0225] The disclosed nitrogen-containing etching compounds can also be used to etch SiN 608 layers under different plasma conditions and with different mixtures. Those skilled in the art will recognize that... Figure 3a and Figure 3b The layer stacking and geometry shown are provided for illustrative purposes only, and the disclosed nitrogen-containing etching compound can be used to etch other types of layer stacks. Furthermore, those skilled in the art will recognize that the number of layers in the stack can vary (i.e., it may include more or fewer than the four layers depicted).

[0226] A vapor of the disclosed nitrogen-containing etching compound is introduced into a reaction chamber containing the substrate and the silicon-containing film. The vapor can be introduced into the chamber at a flow rate ranging from about 0.1 sccm to about 1 slm. For example, for a 200 mm wafer size, the vapor can be introduced into the chamber at a flow rate ranging from about 5 sccm to about 50 sccm. Alternatively, for a 450 mm wafer size, the vapor can be introduced into the chamber at a flow rate ranging from about 25 sccm to about 250 sccm. Those skilled in the art will recognize that the flow rate can vary depending on the tooling.

[0227] The disclosed nitrogen-containing etching compounds can be supplied in pure form or as a blend with an inert gas (such as N2, Ar, He, Xe, etc.) or a solvent. The disclosed nitrogen-containing etching compounds can be present in the blend at varying concentrations. For liquid nitrogen-containing compounds, these nitrogen-containing etching compounds can be produced in vapor form via conventional vaporization steps, such as direct vaporization or by bubbling to vaporize the pure or blended nitrogen-containing etching compound solution. These pure or blended nitrogen-containing etching compounds can be fed as a liquid into a vaporizer before being introduced into the reactor, where they are vaporized.

[0228] Alternatively, the pure or blended nitrogen-containing etching compounds can be vaporized by conveying a carrier gas into a container containing the disclosed nitrogen-containing etching compound or by bubbling a carrier gas into the disclosed nitrogen-containing compound. The carrier gas may include, but is not limited to, Ar, He, N2, and mixtures thereof. Bubbling with a carrier gas also removes any dissolved oxygen present in the pure or blended nitrogen-containing etching compound solution. The carrier gas and the disclosed nitrogen-containing etching compound are then introduced into the reactor as vapor.

[0229] If necessary, the container containing the disclosed nitrogen-containing etching compound can be heated to a temperature that allows the nitrogen-containing etching compound to be in a liquid phase and has a sufficient vapor pressure for delivery to the etching tool. The container can be maintained at a temperature in the range of, for example, about 0°C to about 150°C, preferably from about 25°C to about 100°C, more preferably from about 25°C to about 50°C. More preferably, the container is maintained at room temperature (about 25°C) to avoid heating the piping of the etching tool. Those skilled in the art will recognize that the temperature of the container can be adjusted in known ways to control the amount of vaporized nitrogen-containing compound.

[0230] Furthermore, these nitrogen-containing etching compounds are delivered with a purity ranging from 95% to 99.999% by volume, and can be purified using known standard purification techniques to remove CO, CO2, N2, H2O, HF, H2S, SO2, halides, and other hydrocarbons or hydrohalogenated hydrocarbons.

[0231] An inert gas is also introduced into the reaction chamber to maintain the plasma. The inert gas may be He, Ar, Xe, Kr, Ne, N2, or a combination thereof. Before introduction into the chamber, the etching gas and the inert gas may be mixed, wherein the inert gas constitutes between approximately 0.01% v / v and approximately 99.9% v / v of the resulting mixture. Alternatively, the inert gas may be introduced into the chamber continuously, while the etching gas may be introduced into the chamber in a pulsed manner.

[0232] The disclosed etching gas vapor and inert gas are activated by plasma to generate activated etching gas. The plasma decomposes the etching gas into free radical form (i.e., activated etching gas). The plasma can be generated by applying RF or DC power. The plasma can be generated with RF power ranging from about 25 W to about 10,000 W. The plasma can be generated remotely or within the reactor itself. The plasma can be generated under RF applied at two electrodes in dual CCP or ICP mode. The RF frequency of the plasma can range from 200 kHz to 1 GHz. Different RF sources of different frequencies can be coupled and applied at the same electrode. The plasma RF pulse can be further used to control molecular debris and reactions at the substrate. Those skilled in the art will recognize the methods and apparatus suitable for this plasma treatment.

[0233] Quadrupole mass spectrometry (QMS), optical emission spectrometry, FTIR, or other radical / ion measurement tools can measure the activated etching gas from the chamber exhaust to determine the type and number of species produced. If necessary, the flow rates of the etching gas and / or inert gas can be adjusted to increase or decrease the number of radical species produced.

[0234] The disclosed etching gas may be introduced into the reaction chamber before or within the reaction chamber, and may be mixed with other gases. Preferably, these gases may be mixed before introduction into the chamber to provide an inlet gas of uniform concentration.

[0235] In another alternative, the vapor of the nitrogen-containing compound can be introduced into the chamber independently of other gases, such as when two or more gases react.

[0236] In another alternative, the etching gas and the inert gas are the only two gases used during the etching process.

[0237] Exemplary other gases include, but are not limited to, oxidants such as O2, O3, CO, CO2, NO, N2O, NO2, and combinations thereof. The disclosed etching gases and oxidants may be mixed together before being introduced into the reaction chamber.

[0238] Alternatively, an oxidant may be continuously introduced into the chamber, and an etching gas may be introduced into the chamber in a pulsed manner. The oxidant may constitute between approximately 0.01% v / v and approximately 99.99% v / v of the mixture introduced into the chamber (where 99.99% v / v represents the introduction of an almost pure oxidant for the continuous introduction alternative).

[0239] Other exemplary gases that can be mixed with this etching gas include additional etching gases such as cC4F8, C4F8, C4F6, CF4, CH3F, CF3H, CH2F2, COS, CS2, CF3I, C2F3I, C2F5I, SO2, 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), or cis-1,1,2,2,3,4-hexafluorocyclobutane (cis-C4H2F6).

[0240] The etching gas vapor and an additional gas can be mixed before being introduced into the reaction chamber. The additional etching gas may constitute between approximately 0.01% v / v and approximately 99.99% v / v of the mixture introduced into the chamber.

[0241] In a non-limiting exemplary plasma etching process, vapor of 2,3,3,3-tetrafluoropropionitrile is introduced into a 200 mm dual CCP plasma etching tool using a controlled gas flow device. This controlled gas flow device can be a mass flow controller or a bubbler design, in which an inert gas flow delivers the vapor of the desired molecule. In the case of high-boiling-point molecules, specific low-dropout mass flow controllers from Brooks Automation (GF120XSD), MKS Instruments, etc., can be used. The pressure of the reaction chamber is set at approximately 30 mTorr. Because the vapor pressure of 2,3,3,3-tetrafluoropropionitrile at room temperature is approximately 498 Torr, no gas source heating is required. The distance between the two CCP electrodes is maintained at 1.35 cm, and the RF power of the top electrode is fixed at 750 W. The RF power of the bottom electrode is varied to analyze the properties of the molecules. The reaction chamber contains a substrate on which a silicon-containing film is applied, similar to... Figure 1a Those shown in the diagram. The antireflective coating 108 is patterned / etched using fluorocarbon compounds (e.g., CF4 and CH2F2) and oxygen-containing gases (e.g., O2). The amorphous carbon mask layer is patterned / etched using oxygen-containing gases. The SiO and SiN layers 104 are patterned using plasma of the disclosed nitrogen-containing organic fluorine compounds (e.g., 2,3,3,3-tetrafluoropropionitrile) and argon. Argon is introduced into the chamber independently at a flow rate of 250 sccm. 2,3,3,3-tetrafluoropropionitrile is introduced into the chamber independently at a flow rate of 15 sccm. O2 is introduced into the chamber independently and varied from 0 sccm to 20 sccm to determine the optimal etching conditions. Holes with an aspect ratio equal to or greater than 30:1 are produced, which can be used as channel vias in vertical NAND flash memory. For example, Figure 2 and Figure 3a The other stacked layers shown can be used with similar examples.

[0242] In another non-limiting exemplary plasma etching process, difluoroacetonitrile is introduced into a 200 mm dual CCP plasma etching tool using a controlled gas flow device. This controlled gas flow device can be a mass flow controller. In the case of high-boiling-point molecules, a specific low-pressure-drop mass flow controller from Brooks Automation (model number GF120XSD), MKS Instruments, etc., can be used. The pressure of the reaction chamber is set at approximately 30 mTorr. Because the vapor pressure of difluoroacetonitrile at 20 °C is approximately 900 Torr, gas source heating is not required. The distance between the two CCP electrodes is maintained at 1.35 cm, and the RF power of the top electrode is fixed at 750 W. The RF power of the bottom electrode is varied to analyze the performance of the difluoroacetonitrile. The reaction chamber contains a substrate 100 having a thick SiO layer 104a thereon, similar to... Figure 2 The layer is shown in the diagram. Prior to this process, the antireflective coating 108 is removed by a fluorocarbon compound (e.g., CF4) and an oxygen-containing gas (e.g., O2), and the Ac mask layer 106 is removed by an oxygen-containing gas. Argon gas is introduced independently into the chamber at a flow rate of 250 sccm. Difluoroacetonitrile is introduced independently into the chamber at 15 sccm. O2 is introduced independently into the chamber at 0-20 sccm to determine the optimal etching conditions. Holes with an aspect ratio equal to or greater than 10:1 are produced, which can be used as contact holes in DRAM. For example, Figure 1a and Figure 3a Other stacking layers shown can use similar examples.

[0243] The silicon-containing film reacts with activated etching gas to form volatile byproducts, which are then removed from the reaction chamber. The aC mask, antireflective coating, and photoresist layer are less reactive with the activated etching gas. Therefore, the activated etching gas selectively reacts with the silicon-containing film to form volatile byproducts.

[0244] The temperature and pressure within the reaction chamber are maintained under conditions suitable for the reaction of the silicon-containing film with the activated etching gas. For example, depending on the etching parameters, the pressure within the chamber can be maintained between approximately 0.1 mTorr and approximately 1000 Torr, preferably between approximately 1 mTorr and approximately 10 Torr, more preferably between approximately 10 mTorr and approximately 1 Torr, and even more preferably between approximately 10 mTorr and approximately 100 mTorr. Similarly, the substrate temperature within the chamber can be between approximately -196°C and approximately 500°C, preferably between approximately -120°C and approximately 300°C, more preferably between approximately -100°C and approximately 50°C, and even more preferably between approximately -10°C and approximately 40°C. The chamber wall temperature can be in the range of approximately -196°C to approximately 300°C, depending on process requirements.

[0245] The reaction between the silicon-containing film and the activated etching gas results in the anisotropic removal of the silicon-containing film from the substrate. Nitrogen, oxygen, and / or carbon atoms may also be present in the silicon-containing film. Removal is attributed to the conversion of Si into volatile species, such as SiF, by plasma ionization physical sputtering of the silicon-containing film (accelerated by plasma) and / or by the chemical reaction of plasma species. x , where x is in the range from 1 to 4.

[0246] The plasma-activated vapor of the disclosed nitrogen-containing etching compound preferably exhibits high selectivity for the mask and etches through alternating layers of SiO and SiN, resulting in a vertical etch profile without bends or roughness, which is important for 3D NAND applications. Furthermore, the plasma-activated vapor deposits polymers on the sidewalls to minimize feature profile deformation. For other applications, such as DRAM and 2D NAND, for example, plasma-activated etching gases under different process conditions can selectively etch SiO from SiN. The plasma-activated etching gas can selectively etch SiO and / or SiN from mask layers (such as aC, photoresist, p-Si, or silicon carbide) or from metal contact layers (such as Cu) or from channel regions composed of SiGe or polysilicon regions.

[0247] The disclosed etching process using the disclosed nitrogen-containing etching compound as the etching gas produces channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, etc., in these silicon-containing films. The resulting holes can have aspect ratios ranging from approximately 10:1 to approximately 200:1 and diameters ranging from approximately 5 nm to approximately 50 nm. For example, those skilled in the art will recognize that channel hole etching produces holes in silicon-containing films with aspect ratios greater than 60:1.

[0248] Typical materials to be etched can be SiO. The process of etching SiO may involve etching trenches in borosilicate glass (BPSG), tetraethyl orthosilicate (TEOS), or low deposition rate TEOS (LDTEOS). The etching stop layer can be silicon nitride, silicon oxynitride (SiON), or polycrystalline silicon. The mask material used can be aC, p-Si, or a photoresist material. Here, the nitrogen-containing etching compound disclosed is applied to etch SiO, SiN, p-Si, and / or aC substrate films.

[0249] Example

[0250] The following non-limiting examples are provided to further illustrate embodiments of the invention. However, these examples are not intended to cover all cases and are not intended to limit the scope of the invention described herein.

[0251] In the following examples, the etching properties of nitrogen-containing compounds C2HF2N and C3HF4N are evaluated and compared with those of C5F5N (CAS 700-16-3), C2F3N, and standard gases such as cC4F8 and C4F6. The results show that the nitrogen-containing etch compounds C2HF2N and C3HF4N provide sidewall protection and can be used to etch semiconductor structures, such as contact etching.

[0252] Here, the target etching requirements for the etchant or etching gas used in contact etching are:

[0253] 1. The etching rate of oxides (i.e., SiO) must be high;

[0254] 2. SiO should have a higher selectivity than other materials (typically SiN);

[0255] 3. SiO should have a higher selectivity than other materials (typically p-Si or aC).

[0256] As will be shown, the results for compounds C3HF4N and C2HF2N show greater promise, as they meet all the etching targets required for contact etching applications.

[0257] Four 1x1cm substrates with four different substrate materials (including SiO, SiN, p-Si, and aC) 2 Etching experiments were performed on the samples. The deposition and / or etching rate was measured using an ellipsometry and / or SEM by measuring the change in etch thickness as a function of etching time. The samples were placed on a 200 mm diameter carrier wafer and kept in contact using double-sided carbon ribbons obtained from the 2spi manufacturer. Alternatively, thermal paste could be used to attach the samples to the carrier wafer.

[0258] Deposition tests were conducted at a source power of 30 mTorr and 750 W (27 MHz) at a depth of 1 x 1 cm⁻¹. 2 The process was performed on a Si sample with no bias power at the substrate. The process feed mixture contained 250 sccm of Ar and 15 sccm of etch gas. The deposited test samples were then sent for X-ray photoelectron spectroscopy (XPS) analysis to investigate the type of polymer film formed on the substrate.

[0259] Etching tests were also conducted at a source power of 30 mTorr, 750 W (27 MHz), and a bias power of 1500 W (2 MHz). The feed mixture contained 250 sccm of Ar, 15 sccm of etching gas, and O2 varying from 0 to 15 sccm.

[0260] Figure 4This is an exemplary cross-sectional side view of an exemplary reactor system used in deposition and etching tests. As shown, reactor 800 includes a reaction chamber 802. Inside the reaction chamber 802, a wafer 806 attached to the top of a bottom electrode 804 can be placed in the bottom portion of the reaction chamber 802, and a silicon top electrode nozzle 808 can be placed on the top portion of the reaction chamber 802. The bottom electrode 804 can be an electrostatic chuck with an applied bias power. For example, a 2 MHz RF bias power can be applied to the bottom electrode 804. The wafer 806 can have multiple layers to be etched. The silicon top electrode nozzle 808 has multiple holes 810 in the nozzle through which gas passes. Gas can be introduced into the reaction chamber 802 through a gas inlet 812 and then used for uniform gas distribution through the holes 810 in the nozzle 808. Source power can be applied to the silicon top electrode nozzle 808. For example, a 27MHz RF source power can be applied to the silicon top electrode nozzle 808. Between the silicon top electrode nozzle 808 and the bottom electrode 804 is a plasma region. Gas passing through the holes 810 in the nozzle 808 can be ionized in this plasma region and then etched onto the wafer 806. The gas can be removed by extracting it from the reaction chamber 802 through the outlet 814.

[0261] Furthermore, mass spectrometry can be used to study the electron collisional ionization of the etching gas. For this test, the etching gas is allowed to flow through the mass spectrometer chamber, and a quadrupole mass spectrometer (Hiden Analytical Inc.) detector is used to study the fragments from the etching gas as a function of electron energy.

[0262] Example 1

[0263] Figure 5 This is a graph showing the electron collisional ionization data of C3HF4N. Figure 5 In the diagram, the x-axis represents electron energy and the y-axis represents the partial pressure of the fragment species. Figure 5 The main fragments for C3HF4N are shown to be CF3 and C2HFN. The C2HFN fragments have an F / C ratio of 1:2 and can readily polymerize upon reaching the substrate.

[0264] Example 2

[0265] Figure 6 This is a graph showing the electron collisional ionization data of C2HF2N. Figure 6 In the diagram, the x-axis represents electron energy and the y-axis represents the partial pressure of the fragment species. Figure 6 The main fragments of C2HF2N are shown to be CF2 and C2F2N. The C2F2N fragments have a low F / C ratio and will readily polymerize upon reaching the substrate.

[0266] Example 3

[0267] The deposition test was performed on a blank 1x1cm 2 Experiments were conducted on Si samples where a source power (750 W at 27 MHz) was applied without bias power. Due to the absence of bias power, ions reaching the substrate may not have sufficient energy to etch. Additionally, neutral and active species reaching the surface adhere to the surface based on their adhesion coefficients, depositing a thin polymer layer. This thin polymer layer is likely the reason for the often selective sidewall passivation. The deposition test experimental conditions helped simulate the polymer layer formed during plasma-processed patterns on the surface or sidewalls.

[0268] After the deposition test had been running for 60 seconds, a 260 nm polymer film was deposited on Si at 30 mTorr pressure using a process gas mixture containing 250 sccm of Ar and 15 sccm of C2F3N. The deposition rate of C2F3N was therefore 260 nm / min.

[0269] Under the same deposition test conditions, C2HF2N was found to produce a deposition rate of 150 nm / min, and C3HF4N produced a deposition rate of 190 nm / min. For C5F5N, deposition tests were conducted for 60 seconds at 30 mTorr pressure using a process gas mixture containing 250 sccm of Ar and 5 sccm of C5F5N, and it produced a deposition rate of 120 nm / min.

[0270] The samples were then sent for XPS analysis, in which the properties of the polymer layer were investigated. Figure 7 This provides a graph of XPS data for the polymer film formed using C3HF4N during deposition testing. (Source: [Original Source Name]) Figure 7 The broad elemental scan from XPS analysis clearly shows the presence of C, F, O, and N peaks, providing evidence of nitrogen in the polymer film. Therefore, nitrogen is present in the polymer film and can act as a better sidewall passivation layer and help generate a vertical profile during high aspect ratio etching.

[0271] Example 4

[0272] Figure 8 This is a graph showing the etching rates of SiO, SiN, p-Si, and aC using C2HF2N and O2. Figure 8 In the diagram, the positive y-axis represents the etching rate and the negative y-axis represents the deposition rate; the x-axis is the O2 flow rate in sccm; the C2HF2N flow rate is fixed at 15 sccm, while the O2 flow rate varies from 0 to 15 sccm.

[0273] As shown, when no oxygen is added (O2 conditions at 0 sccm), C2HF2N readily etches silicon oxide but not other substrates. This is a very important result because C2HF2N etches silicon oxide and protects other substrate materials, providing virtually unlimited selectivity for the oxide compared to other substrate materials. Small damage of a few nanometers due to plasma ion bombardment is expected before the etching gas begins to protect other substrate materials. This damage is not characteristic and is not considered in the selectivity measurements. When 5 sccm of oxygen is added to the mixture, the etching rate of silicon oxide decreases compared to 0 sccm oxygen conditions, but C2HF2N still deposits on all other substrates, preserving the selectivity of the oxide compared to other substrate materials. When 10 sccm of oxygen is added to the mixture, the etching rate of silicon oxide continues to decrease, but C2HF2N still deposits on all other substrates, preserving the selectivity of silicon oxide compared to other substrate materials. When 15 sccm of oxygen is added to the mixture, although the etching rate of silicon oxide decreases again, C2HF2N still deposits on nitrides and p-Si, preserving the selectivity of silicon oxide over silicon nitrides and p-Si. Under O2 testing conditions of 15 sccm, etching was observed on aC, and the selectivity of silicon oxide compared to aC decreased dramatically from infinity to approximately 2 (i.e., etch rate of SiO / etch rate of aC). Overall, C2HF2N offers the widest possible range of process conditions, providing virtually unlimited selectivity for both silicon nitride and p-Si substrates. The etch rate of silicon oxide is lower than that of standard cC4F8 gas (which exceeds 550 nm / min), but can be easily increased by adding additive gases such as CF4, C3F8, cC4F8, or C4F6.

[0274] Example 5

[0275] Figure 9 This is a graph showing the etching rates of SiO, SiN, p-Si, and aC using C3HF4N and O2. Figure 9 In the diagram, the positive y-axis represents the etching rate and the negative y-axis represents the deposition rate; the x-axis is the O2 flow rate in sccm; the C3HF4N flow rate is fixed at 15 sccm, while the O2 flow rate varies from 0 to 15 sccm.

[0276] As shown, C3HF4N deposits on all substrates without the addition of oxygen (O2 conditions at 0 sccm). When 5 sccm of oxygen is added to the mixture, C3HF4N begins to etch silicon oxide, but deposits on all other substrate materials, providing virtually unlimited selectivity for silicon oxide compared to other substrate materials. Similar behavior is observed at 10 sccm of O2. When 15 sccm of oxygen is added, C3HF4N begins to etch silicon nitride, and the selectivity for silicon nitride decreases to approximately 3 (i.e., etch rate of SiO / etch rate of SiN), while still maintaining a high selectivity of approximately 40 for aC.

[0277] Example 6

[0278] Figure 10 This is a graph showing the etching rates of SiO, SiN, p-Si, and aC using C3HF4N and CF4. Figure 10 In the diagram, the y-axis represents the etching rate, and the x-axis represents the CF4 flow rate in sccm. The C3HF4N flow rate was fixed at 15 sccm, the O2 flow rate was fixed at 5 sccm, and the CF4 flow rate was varied from 10 to 15 sccm.

[0279] To improve the etching rate of SiO, comparable to that of cC4F8 (see comparative examples below), CF4 was added to an etching gas mixture of 250 sccm of Ar and 15 sccm of C3HF4N. Figure 10 The graph shows that by adding CF4 to the process gas mixture, the etching rate of SiO has been increased to a maximum of 500 nm / min while maintaining good selectivity for p-Si and aC. Additives (like C) can be added... x F 2x+2 (x = 1 to 5), C x F 2x (x = 3 to 5), C x F 2x-2 (x = 4 to 5) is added to the mixture to improve the oxide etching rate.

[0280] Comparison Example 1

[0281] Figure 11 This is a comparative curve showing the silicon oxide etching rates of C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 etching gases. Figure 11 In the diagram, the positive y-axis represents the etching rate and the negative y-axis represents the deposition rate; the x-axis represents the compound to be compared. Figure 11 The nitrogen-containing compounds C2HF2N and C2F3N were shown to have higher etch rates than C3HF4N and C5F5N.

[0282] Comparison Example 2

[0283] Figure 12 This is a comparative graph showing the selectivity of silicon oxide over silicon nitride using C3HF4N, C2HF2N, C5F5N, C2F3N, C4F8, and C4F6 etching gases in the absence of oxygen addition. Figure 12 In the diagram, the y-axis represents the SiO:SiN selectivity; the x-axis represents the compounds being compared. Figure 12 The presence of infinite selectivity (denoted as 150) of silicon oxide over silicon nitride in C2HF2N and C5F5N with the addition of 0 sccm of oxygen is shown.

[0284] Comparison Example 3

[0285] Figure 13 This is a comparative graph showing the etching rates of silicon oxide using etching gases including C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 with an oxygen addition of 5 sccm. Figure 13 In the diagram, the y-axis represents the etching rate, and the x-axis represents the compounds being compared. For example... Figure 13 The etching rates shown are ordered as follows with 5 sccm of oxygen added: cC4F8>C2F3N>C3HF4N>C2HF2N>C4F6>C5F5N.

[0286] Comparison Example 4

[0287] Figure 14 This is a comparative graph showing the selectivity (SiO / SiN) of the etching gases C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 under 5 sccm oxygen addition. Figure 14 In the diagram, the y-axis represents the SiO:SiN selectivity, and the x-axis represents the compounds being compared. Figure 14 The presence of 5 sccm of oxygen in the presence of C3HF4N, C2HF2N, and C5F5N with an infinite selectivity for oxides compared to nitrides is shown, denoted as 150.

[0288] Comparison Example 5

[0289] Figure 15 This is a comparative graph showing the silicon oxide etching rates of C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 etching gases under 10 sccm oxygen addition. Figure 15 In the diagram, the y-axis represents the etching rate, and the x-axis represents the compounds being compared. For example... Figure 15The etching rates shown are ordered as follows with 10 sccm of oxygen added: cC4F8>C4F6>C3HF4N>C2F3N>C2HF2N>C5F5N.

[0290] Comparison Example 6

[0291] Figure 16 This is a comparative graph showing the selectivity (SiO / SiN) of the etching gases C3HF4N, C2HF2N, C5F5N, C2F3N, cC4F8, and C4F6 under 10 sccm oxygen addition. Figure 16 In the diagram, the y-axis represents the SiO:SiN selectivity, and the x-axis represents the compounds being compared. Figure 16 The oxide-to-nitride selectivity of C3HF4N, C2HF2N, and C5F5N with the addition of 10 sccm of oxygen is shown to be infinite, expressed as 150.

[0292] Comparison Example 7

[0293] Figure 17 This is a comparative graph showing the silicon oxide etching rates of C3HF4N, C2HF2N, C2F3N, cC4F8, and C4F6 etching gases under 15 sccm oxygen addition. Figure 17 In the diagram, the y-axis represents the etching rate, and the x-axis represents the compounds being compared. For example... Figure 17 The etching rates shown are ordered as follows with 15 sccm of oxygen added: C4F6 > C4F8 > C3HF4N > C2F3N > C2HF2N.

[0294] Comparison Example 8

[0295] Figure 18 This is a comparative graph showing the selectivity (SiO / SiN) of the etching gases C3HF4N, C2HF2N, C2F3N, cC4F8, and C4F6 under 15 sccm oxygen addition. Figure 18 In the diagram, the y-axis represents the etching rate, and the x-axis represents the compound being compared. Figure 18 It is shown that, with the addition of 15 sccm of oxygen, only C2HF2N has an infinite selectivity for oxides compared to nitrides, which is expressed as 150.

[0296] Comparison Example 9

[0297] N2 was added to the etching gas mixture (containing cC4F8) to observe its effect on etching rate and selectivity. Etching tests were performed at a source power of 30 mTorr, 750 W (27 MHz), and a bias power of 1500 W (2 MHz). The feed mixture contained 250 sccm of Ar, 15 sccm of cC4F8, and 10 sccm of O2, while N2 varied in amounts from 0 sccm to 20 sccm. Figure 19 This is a graph showing the effect of adding N2 on the etching rate of different substrate materials. Figure 19 In the diagram, the y-axis represents the etching rate, and the x-axis represents the N2 flow rate.

[0298] As shown, for each substrate (SiO, SiN, p-Si, or aC), the etching rate change is less than 10% compared to the etching rate without nitrogen (0 sccm). Therefore, based on Figure 19 The results shown indicate that nitrogen addition has minimal impact on the etching rate of different substrate materials.

[0299] Comparison Example 10

[0300] NH3 was added to the etching gas mixture to observe the effect of nitrogen on etching rate and selectivity. Etching tests were performed at a source power of 30 mTorr, 750 W (27 MHz), and a bias power of 1500 W (2 MHz). The feed mixture contained 250 sccm of Ar, 15 sccm of cC4F8, and 15 sccm of NH3, while O2 varied from 0 sccm to 15 sccm. Figure 20 This is a graph showing the effect of adding O2 on the etching rate of different substrate materials. Figure 20 In the diagram, the positive y-axis represents the etching rate and the negative y-axis represents the deposition rate; the x-axis represents the O2 flow rate.

[0301] As shown, when no oxygen is added, silicon oxide exhibits virtually unlimited selectivity compared to silicon nitride. However, these conditions lead to excessive polymerization, resulting in etch termination.

[0302] As mentioned above Figure 1b As described, polymers can be deposited on the sidewalls during etching. To obtain a deep, straight etch profile, the amount of polymer deposited must be carefully controlled. Over-polymerization can lead to a phenomenon known as etch termination. To prevent etch termination, oxygen is often added to the etching gas mixture. However, excessive oxygen can lead to a loss of selectivity. Therefore, a trade-off exists between etch termination and selectivity.

[0303] like Figure 20As shown, selectivity decreases with the addition of oxygen. This is compared to adding ammonia to cC4F8 and varying the oxygen flow rate between 5 sccm and 15 sccm (reference). Figure 8 and Figure 9 The selectivity of nitrogen-containing organofluorine compounds in SiO is significantly better than that of other materials. Furthermore, the requirement for ammonia in another major organofluorine compound in the mixture makes it difficult to use in commercial applications.

[0304] Deposition tests were conducted at a source power of 30 mTorr and 750 W (27 MHz) at a depth of 1 x 1 cm⁻¹. 2 The deposition was performed on a Si sample without bias power. The process feed mixture contained 250 sccm of Ar, 15 sccm of cC4F8, and 15 sccm of NH3. Under these conditions, a deposition rate of 180 nm / min was observed.

[0305] Comparison Example 11

[0306] Figure 21 This is a graph showing the electron collisional ionization data of C2F3N. Figure 21 In the diagram, the x-axis represents electron energy and the y-axis represents the partial pressure of the fragment species. Figure 21 The main fragments for C2F3N are shown to be CF3 and C2F2N. C2F2N fragments have a low F / C ratio and will readily polymerize upon reaching the substrate.

[0307] Comparison Example 12

[0308] Figure 22 This is a graph showing the etching rates of SiO, SiN, p-Si, and aC using C2F3N and O2. Figure 22 In the diagram, the positive y-axis represents the etching rate and the negative y-axis represents the deposition rate; the x-axis is the O2 flow rate in sccm. The C2F3N flow rate was fixed at 15 sccm, while the O2 flow rate varied from 0 to 15 sccm.

[0309] As shown, C2F3N readily etches silicon oxide when no oxygen is added (O2 conditions at 0 sccm), but etches other substrates at a very slow rate. This results in a very high selectivity of approximately 40% for silicon oxide compared to silicon nitride, and approximately 30% for silicon oxide compared to aC, with virtually unlimited selectivity for p-Si. However, the selectivity slowly decreases as the oxygen flow rate increases to 5 sccm and beyond.

[0310] Comparison Example 13

[0311] Figure 23 This indicates that C3H3F6N(1,1,1,3,3,3-hexafluoroisopropylamine) A graph of electron collision ionization data. Figure 23 In the diagram, the x-axis represents electron energy and the y-axis represents the partial pressure of the fragment species. Figure 23 The primary fragment for C3H3F6N is shown to be C2H3F3N. C2H3F3N fragments have a high F / C ratio and may not provide an etch-resistant polymer on the substrate.

[0312] Comparison Example 14

[0313] Figure 24 This is a graph showing the etching rate of C3H3F6N on different substrate materials without oxygen addition. For the deposition test conditions, it was deposited at 210 nm / min and thus provides sidewall protection. The molecule offers good selectivity for p-Si and aC, but loses selectivity for SiN films even without any oxygen addition.

[0314] In summary, the evaluation of plasma dry etching of SiO, SiN, p-Si, and aC films using nitrogen-containing organofluorine compounds (HFCs) demonstrated that nitrogen-containing HFCs produced the highest (up to infinity) selectivity for silicon oxide compared to silicon nitride and p-Si, compared to prior art fluorocarbons. The high selectivity is likely attributed to the formation of low-F / C nitrogen-containing fragments during the plasma dissociation of the etching gas, which results in the formation of a protective polymer film on the substrate. This polymer film showed evidence of C, F, and N when analyzed by XPS. The resulting film has the formula CF. x N y Where x, y = 0.01 to 5. With standard cC4F8 gas (where only CF is formed) x Compared to polymers of the type where x = 0.01 to 5, the presence of nitrogen in the polymer film provides an additional protective layer. The etching gas results presented here show that they are not only suitable for contact etching processes, but may also be beneficial for other etching processes on silicon- or metal-containing substrates.

[0315] Although embodiments of the invention have been shown and described, those skilled in the art can modify them without departing from the spirit or teachings of the invention. The embodiments described herein are merely exemplary and non-limiting. Many variations and modifications of composition and methods are possible and within the scope of the invention. Therefore, the scope of protection is not limited to the embodiments described herein, but is defined only by the following claims, the scope of which should include all equivalents of the subject matter of those claims.

Claims

1. A method for depositing an etch-resistant polymer layer on a substrate, the method comprising (a) introducing a vapor of an organofluorine compound into a reaction chamber containing the substrate, wherein the organofluorine compound has a structural formula selected from: (i)N≡CR 1 , where R 1 Having the formula H a F b C c , where a = 1 - 11, b = 1 - 11, and c = 1 - 5; (ii)(N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 0-11, b = 1-11, and c = 1-5; as well as (iii)R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, and x + z = 1 - 3, each R 1 and R 2 Independently possessing the formula H a F b C c (a) where a = 0-11, b = 0-11, and c = 0-5; and (b) plasma activation of the organofluorine compound to form an etch-resistant polymer layer on the substrate; The organic fluorine compound has a purity ranging from 95% to 99.999% by volume and contains water vapor impurities ranging from 10 to 5% by volume.

2. The method according to claim 1, wherein the organofluorine compound has the following formula: (i)N≡CR 1 , where R 1 Having the formula H a F b C c Where a = 1 - 11, b = 1 - 11, and c = 1 - 5; or (ii)(N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 0-11, b = 1-11, and c = 1-5.

3. The method according to claim 1, wherein the organofluorine compound has the following formula: (iii)R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, and x + z = 1 - 3, each R 1 and R 2 Independently possessing the formula H a F b C c , where a = 0-11, b = 0-11, and c = 0-5.

4. The method according to claim 1, wherein the organofluorine compound is selected from the group consisting of 2,2,3,3-tetrafluoropropionitrile, 2,3,3,3-tetrafluoropropionitrile (C3HF4N), difluoroacetonitrile (C2HF2N), trifluoroacetonitrile (C2F3N), nonafluoropentadienonitrile (C5F9N), pentafluoroallyl cyanide (C4F5N), hexafluoroacetone imine (C3HF6N), 4,4,4-trifluorocrotonitrile, 3,3,3-trifluoropropionitrile, fluoroacetonitrile, octafluorohexane-1,6-dianitronitrile, 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene, N,1,1,3,3,3-heptafluoropropane, and 1,1,1,6,6,6-hexafluoro-3-azahex-3-ene.

5. The method according to claim 4, wherein the organofluorine compound is 2,3,3,3-tetrafluoropropionitrile (C3HF4N).

6. The method according to claim 4, wherein the organofluorine compound is difluoroacetonitrile (C2HF2N).

7. The method according to claim 4, wherein the organofluorine compound is trifluoroacetonitrile (C2F3N).

8. The method of claim 1, wherein the etch-resistant polymer layer forms an N-containing polymer passivation layer on the sidewall of the patterned etched structure.

9. The method of claim 8, wherein the aspect ratio of the patterned etched structure is from 1:1 to 50:

1.

10. The method of claim 8, wherein the aspect ratio of the patterned etched structure is from 10:1 to 200:

1.

11. The method of claim 8, wherein the N-containing polymer passivation layer prevents ions and free radicals from etching the sidewalls.

12. The method of claim 8, wherein the etch-resistant polymer layer results in a patterned etched structure with a straight and unbent vertical profile.

13. The method according to any one of claims 1 to 12, the method further comprising removing the etch-resistant polymer layer using a dry or wet etch chemical method.

14. The method according to any one of claims 1 to 12, the method further comprising introducing an inert gas into the reaction chamber.

15. The method of claim 14, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, N2 and combinations thereof.

16. A method for depositing an N-containing polymer passivation layer on a substrate, the method comprising (a) introducing a vapor of an organofluorine compound into a reaction chamber containing the substrate, the organofluorine compound having a structural formula selected from: (i)N≡CR 1 , where R 1 Having the formula H a F b C c , where a = 1 - 11, b = 1 - 11, and c = 1 - 5; (ii)(N≡C-)-(R 2 )-(-C≡N), where R 2 Having the formula H a F b C c , where a = 0-11, b = 1-11, and c = 1-5; as well as (iii)R 1 x [-C=N(R 2 z )] y Where x = 1 - 2, y = 1 - 2, z = 0 - 1, and x + z = 1 - 3, each R 1 and R 2 Independently possessing the formula H a F b C c (a) = 0-11, (b) = 0-11, and (c) = 0-5; and (b) generating fragments of organofluorine compounds by activating plasma to form an N-containing polymer passivation layer on the substrate. The organic fluorine compound has a purity ranging from 95% to 99.999% by volume and contains water vapor impurities ranging from 10 to 5% by volume.

17. The method according to claim 16, wherein the organofluorine compound is selected from the group consisting of 2,2,3,3-tetrafluoropropionitrile, 2,3,3,3-tetrafluoropropionitrile (C3HF4N), difluoroacetonitrile (C2HF2N), trifluoroacetonitrile (C2F3N), nonafluoropentadienonitrile (C5F9N), pentafluoroallyl cyanide (C4F5N), hexafluoroacetone imine (C3HF6N), 4,4,4-trifluorocrotonitrile, 3,3,3-trifluoropropionitrile, fluoroacetonitrile, octafluorohexane-1,6-dianitronitrile, 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene, N,1,1,3,3,3-heptafluoropropane, and 1,1,1,6,6,6-hexafluoro-3-azahex-3-ene.

18. The method according to claim 16 or 17, the method further comprising removing the N-containing polymer passivation layer using a dry or wet etching chemical method.

19. The method according to claim 16 or 17, the method further comprising introducing an inert gas into the reaction chamber.

20. The method of claim 19, wherein the inert gas is selected from the group consisting of He, Ar, Xe, Kr, Ne, N2 and combinations thereof.

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