Etching method with alternating non-plasma and plasma etching processes

Abstract

A method for forming a pattern of holes in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method comprising 1) exposing the substrate to a vapor of passivating molecules under non-plasma conditions for a period of time to form a surface protection layer on the patterned mask layer, 2) exposing the substrate to a plasma activated etch gas and plasma dry etching the substrate with the plasma activated etch gas to form holes on the patterned mask layer in the film, and 3) repeating steps 1) and 2) until a desired hole pattern is formed in the film, wherein the surface protection layer is also formed on sidewalls of pores formed in the film, and wherein the passivation molecules have a boiling point equal to or greater than 20 DEG C.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 974,246, filed on October 26, 2022, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention relates to an etching method with alternating non-plasma and plasma etching processes using passivating molecules that condense, chemically adsorb or chemically react with a surface to form a protective layer on the surface. Background of the Invention

[0005] In a continuous plasma etching process, surface modification (activation) and energetic material removal (desorption) are performed simultaneously. However, performing them simultaneously is problematic because changing plasma parameters to improve one aspect may degrade another aspect. For silicon-based dielectric etching, balancing the ratio of active radicals (such as F, Cl) to passivating radicals (such as H, CH-) is important and needs to be optimized so that the appropriate chemical reactions occur to form easily depleted volatile byproducts or protective deposits on the rest (selectivity and profile control). However, fluorinated chemicals are often accompanied by undercuts and proximity effects and are limited to forming relatively wide shallow grooves or trenches. Chlorinated gas chemicals have profile control issues and are affected by phenomena such as black silicon.

[0006] Therefore, there has been an ongoing effort to develop new etch chemistries to evolve the etching challenges that may be caused by: ever-decreasing device dimensions; changes in the materials used, such as high-k or low-k dielectrics; diversification of device architectures, such as FinFET and 3D NAND transistors, and new packaging approaches such as TSV technology. To this end, heavier compounds, which typically have high boiling points, have recently been extensively studied for etching semiconductor materials to form deep, narrow trenches with controlled profiles. At the same time, novel processes, such as multi-step etching, combinations of deposition / etching, etc., have been developed to etch structures with desired or larger aspect ratios.

[0007] Plasma etching in high aspect ratio structures is a complex process that utilizes many different fluorocarbon etch gases to control its etch rate, selectivity to the mask, and profile control. Sidewall passivation layers are critical to controlling the profile and reducing bowing. The polymer deposited by the fluorocarbon gas also helps protect the carbon mask from bombarding Ar + ions and oxygen radicals. Mask selectivity can be improved by both surface coatings that resist etching and conductive sidewall passivation layers that increase the etch rate.

[0008] US20210020450 discloses an etching method according to an embodiment, the etching method comprising alternately switching a first step and a second step. In the first step, a first gas containing fluorine atoms is introduced without supplying a radio frequency voltage to form a surface layer on the surface of a target, and the target is cooled at a temperature equal to or lower than the liquefaction temperature of the first gas. In the second step, a second gas that is gaseous at the first temperature and different from the first gas is introduced, and a radio frequency voltage is supplied to generate plasma from the second gas, and the target is etched by sputtering using the plasma. The first gas contains a composition formula C x H y F z A fluoride gas represented by wherein x≥1, y≥0, z≥2. This limits the first gas to a gas containing F.

[0009] US20210202260 discloses a technique that enables etching of a film on a substrate with reduced etching on the sidewall surface. The etching method includes forming a protective layer on the sidewall surface defining a recess in the substrate. The protective layer contains sulfur atoms. The etching method further includes etching the film on the substrate to increase the depth of the recess after forming the protective layer. The protective layer on the surface is formed under plasma conditions. A method including CHF 3 Several examples of .

[0010] Zhang et al. (“Improved Plasma Resistance for Porous Low-k Dielectrics”, ECS J. Solid State Sci. Tech., 4, N3098-N3107, 2015 and PESM 2014, Grenoble, France) disclosed the low-damage integration of ultra-low-k porous organosilicate glasses by a hole filling method. Zhang et al. introduced the concept of “capillary condensation” and condensed liquid precursors into the micropores of low-k dielectric materials (so-called low-k filling), even at pressures below the vapor pressure. The benefit of hole filling is a significant improvement in trench sidewall damage, since protection is achieved independently of etching byproducts. In the low-k filling process, the filled samples are prepared in four steps: surface pretreatment, polymer spin coating, thermal drive-in, and surface cleaning. It relies on the unique porous structure of low-k materials (no results were reported for non-porous materials). The disclosure of Zhang et al. should not be affected. Hole filling is performed in several ways:

[0011] 1) Pore filling using liquid condensation at low temperatures;

[0012] 2) The polymer is deposited on the low-k surface by spin coating from a polymer solution. Through thermal annealing well above the glass transition of the polymer, the solvent evaporates and the polymer penetrates into the porous low-k structure.

[0013] US 9543158 to Nikhil et al. discloses various methods, apparatus and systems for forming recessed features in dielectric materials on substrates. In some cases, a protective coating is deposited using plasma assisted atomic layer deposition, modified plasma assisted atomic layer deposition, or plasma assisted chemical vapor deposition. US10170324 B2 is similar. In these patents, a protective coating is deposited using precursor reactants and co-reagents of many different types of families to form a deposited layer on the sidewalls, which is performed in a cyclic etching mode of etching / deposition.

[0014] US10361092 describes adding a metal-containing component to an etching process together with a fluorocarbon etching gas, wherein the metal component is selected from at least one of tungsten (W), tin (Sn), molybdenum (Mo), ruthenium (Ru), titanium (Ti) or tantalum (Ta); and the source of the metal may include WF 6 、TiCl 4 、TiF 4 SnH 4 、TaF 5 , RuF 6 and SnCl 4 .

[0015] US10741407 describes a method in which a gas containing metal WF 6 Added to high aspect ratio etches to improve sidewall protection by reducing or eliminating problematic sidewall notching.

[0016] US20210242032 describes a method for depositing a metal-containing protective film on the sidewalls of a feature using an etching and deposition cycle process, wherein the protective film is tungsten carbonitride, tungsten sulfide, tin, tin-containing compounds, molybdenum, molybdenum-containing compounds, ruthenium sulfide, aluminum sulfide, zirconium, and zirconium-containing compounds.

[0017] US 9673058 describes a method in which a gas containing W (tungsten) such as WF 6 、WF 5 Cl, WBr 6 、W(CO) 6 , or WCl 6 Added to a carbon-containing passivation gas such as a hydrocarbon, fluorocarbon, or fluorocarbon gas to etch features into a film containing silicon oxide, thereby forming a sidewall passivation layer containing a passivation of tungsten and carbon. The addition of W is expected to improve the etch resistance of the sidewall passivation layer.

[0018] US20180286707 A1 describes a method for etching a high aspect ratio structure in a cyclic and low temperature etching process (<-20°C). The method comprises: a) receiving a substrate in a substrate holder; (b) cooling the substrate by cooling a cooler chamber to a temperature of about -20°C or less; and (c) flowing a mixture of reactants into a chamber, generating a plasma from the mixture of reactants using a plasma source, and etching a dielectric material of the substrate to form a feature in the substrate, wherein the mixture of reactants comprises at least one reactant selected from the group consisting of: iodofluorocarbons, bromofluorocarbons, iodofluorides, HI, HBr, IBr, SF 6 、SO 2 , CS 2 , COS, CF 4 , C 2 F 6 , C 3 F 8 , C 4 F 10 , CHF 3 , and C 2 HF 5 Cryogenic etching temperatures can be used to adjust the adhesion coefficients of various reactants and other species present during etching.

[0019] US20220199418 discloses a method for processing a substrate, the method comprising performing a cyclic plasma etching process comprising two plasma steps and one of these steps comprising silicon molecules.

[0020] Despite the wide range of choices available for etching using Si-containing etchants, additional etchants are continually sought to provide the equipment engineer with the ability to tune etching conditions and manufacturing process requirements and achieve etching goals at desired etch rates, selectivity to mask, and profile control. Summary of the invention

[0021] A method for forming a hole pattern in a substrate is disclosed, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method comprising the steps of:

[0022] 1) exposing the substrate to vapor of passivating molecules for a period of time under non-plasma conditions to form a surface protection layer on the patterned mask layer;

[0023] 2) exposing the substrate to a plasma-activated etching gas, and plasma dry etching the substrate with the plasma-activated etching gas to form holes on the patterned mask layer in the film; and

[0024] 3) Repeating steps 1) and 2) until the desired hole pattern is formed in the membrane,

[0025] Wherein the surface protection layer is also formed on the sidewalls of the holes formed in the membrane. The disclosed method may include one or more of the following aspects:

[0026] Step 1) and step 2) are not performed simultaneously;

[0027] The vaporization temperature of the passivation molecules is greater than the process temperature in step 1);

[0028] The process temperature in step 1) is the same as the process temperature in step 2);

[0029] The process temperature in step 1) ranges from -150°C to 100°C;

[0030] The process temperature in step 1) ranges from -50°C to 50°C;

[0031] The process temperature in step 2) ranges from -150°C to 50°C;

[0032] The process temperature in step 2) is 20°C;

[0033] The inactivating molecule has a boiling point equal to or greater than 20°C;

[0034] The passivating molecule is selected from the group consisting of halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons;

[0035] The passivation molecule is SiH 2 I 2 ;

[0036] · The passivation molecule is selected from Ar, N 2 , Xe, Kr, Ne, or a combination thereof;

[0037] Etching gas has the formula: C x H y F z , where x=1-6, y=0-3, z=1-10;

[0038] The etching gas is selected from CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , C 4 F 6 , C 4 F8 , C 4 F 10 , C 5 F 8 or C 6 F 6 C 1 -C 6 Fluorocarbon gas, or selected from CH 3 F, CH 2 F 2 , CHF 3 , C 2 H 5 F.C 3 H 7 F.C 4 H 2 F 6 , C 3 H 2 F 6 or C 2 HF 5 C 1 -C 6 Hydrofluorocarbon gases;

[0039] Etching gas is C 4 F 6 ;

[0040] Etching gas is CHF 3 ;

[0041] The process pressure in step 1) ranges from 0.001 Torr to 50 Torr;

[0042] The process pressure in step 1) ranges from 300 mTorr to 1 Torr;

[0043] The time period in step 1) varies from 0.01 seconds to 10,000 seconds;

[0044] The time period in step 1) varies from 1 second to 60 seconds;

[0045] The plasma process time in step 2) varies from 0.01 seconds to 10,000 seconds;

[0046] The plasma process time in step 2) varies from 1 second to 60 seconds;

[0047] ·The film is SiO 2 , SiN, SiC, SiCN, or SiON layers, or alternating SiO / SiN or SiO / p-Si layers;

[0048] · further comprising selecting from O 2 ,CO,CO 2 ,NO,NO 2、N 2 adding an oxidant of O to the plasma activated etching gas, wherein the oxidant is plasma activated;

[0049] further comprising the step of purging with an inert gas between these exposing steps;

[0050] further comprising the step of evacuating to process pressure using a vacuum pump between these exposing steps; and

[0051] • Further comprising the step of evacuating to a base pressure of the vacuum pump using the vacuum pump between the exposing steps.

[0052] Also disclosed is a method for forming a hole pattern in a substrate including a film disposed thereon and a patterned mask layer disposed on an oxide layer, the method comprising:

[0053] 1) exposing the substrate to a gas of passivating molecules for a certain period of time under non-plasma conditions to form a surface protection layer on the patterned mask layer;

[0054] 2) exposing the substrate to a plasma-activated etching gas, and performing plasma dry etching on the substrate with the plasma-activated etching gas to form holes on the patterned mask layer in the oxide layer; and

[0055] 3) repeating steps 1) and 2) until a desired oxide hole pattern is formed in the oxide layer,

[0056] The surface protection layer is also formed on the sidewalls of the holes in the oxide layer. The disclosed method may include one or more of the following aspects:

[0057] The vaporization temperature of the passivation molecules is greater than the process temperature in step 1); and

[0058] · further comprising selecting from O 2 ,CO,CO 2 ,NO,NO 2 、N 2 An oxidant of O is added to the plasma-activated etching gas, wherein the oxidant is plasma-activated.

[0059] Also disclosed is a method of forming a hole pattern in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method comprising:

[0060] 1) Expose the substrate to SiH 2 I 2 vapor for a certain period of time to form a surface protection layer on the patterned mask layer;

[0061] 2) exposing the substrate to a plasma-activated fluorocarbon or hydrofluorocarbon etching gas, and plasma dry etching the substrate with the plasma-activated fluorocarbon or hydrofluorocarbon etching gas to form holes on the patterned mask layer in the film; and

[0062] 3) Repeating steps 1) and 2) until the desired hole pattern is formed in the membrane,

[0063] Wherein the surface protection layer is also formed on the sidewalls of the holes in the membrane. The disclosed method may include one or more of the following aspects:

[0064] The vaporization temperature of the passivation molecules is greater than the process temperature in step 1).

[0065] Symbols and nomenclature

[0066] The following detailed description and claims make use of a number of abbreviations, symbols, and terms that are commonly known in the art, and include:

[0067] As used herein, the indefinite article "a" or "an" means one or more than one.

[0068] As used herein, "about" or "around" or "approximately" in the text or claims means ±10% of the stated value.

[0069] As used herein, "room temperature" in the text or claims means about 20°C to about 25°C.

[0070] The term "substrate" refers to one or more materials on which a process is performed. A substrate may refer to a wafer having one or more materials on which a process is performed. A substrate may be any suitable wafer used in semiconductor, photovoltaic, flat panel or LCD-TFT device manufacturing. A substrate may also have one or more layers of different materials deposited thereon from previous manufacturing steps. For example, a wafer may include a silicon layer (including but not limited to crystalline, amorphous, porous, etc.), a silicon-containing layer (including but not limited to SiO 2 , SiN, SiON, SiCOH, etc.), metal or metal-containing layers (including but not limited to copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.) or combinations thereof. In addition, the substrate can be planar or patterned. The substrate can be an organic patterned carbon iodide layer film. The substrate can include dielectric materials (e.g., based on ZrO2) used as field effect transistors (FETs) such as FinFETs, MOFSETs, GAAFETs (all-around gate FETs), ribbon FETs, nanosheets, fork-sheet FETs, complementary FETs (CFETs), MEMS, 3D NAND, MIMs, DRAMs, or FeRam devices. 2Materials based on HfO 2 Materials based on TiO 2 The substrate may include an oxide layer of a material (e.g., a material based on rare earth oxides, a material based on ternary oxides, etc.) or a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode. The substrate may include alternating layers of oxide (e.g., SiO) and nitride (e.g., SiN). One of ordinary skill in the art will recognize that the term "film" or "layer" as used herein refers to a certain thickness of a material laid or spread on a surface and that the surface may be a groove or line. Throughout the specification and claims, the wafer and any associated layers thereon are referred to as a substrate. The substrate may be any solid having functional groups on its surface that tend to react with the reactive heads of the self-assembled monolayer (SAM), and may include, without limitation, a 3D object or powder.

[0071] The term "wafer" or "patterned wafer" refers to a wafer having a stack of films on a substrate, at least the topmost film of the stack of films having a topographical feature or pattern that has been produced in a step prior to etching, and a patterned topmost film is formed for pattern etching.

[0072] The term "processing" as used herein includes patterning, exposing, developing, etching, depositing, cleaning, and / or removal of by-products as necessary to form the described structures.

[0073] The term "deposit" or "deposition" refers to a series of processes in which materials at the atomic or molecular level are deposited as a thin layer from the gaseous state (vapor) to the solid state on the surface of a wafer or substrate. Chemical reactions are involved in the process, which occur after generating a plasma of a reactive gas or after activating the reactive gas by heating. The plasma can be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron cyclotron resonance (ECR) plasma, or a microwave plasma, but is not limited thereto. Suitable commercially available plasma etching chambers include, but are not limited to, those sold under the trademark Flex TM Or Tokyo Electron Tactras TM or Episode TM Lam Research's Dual CCP Reactive Ion Etcher Dielectric Etch Product Line sold by UL. The non-plasma exposure step can be performed in a different chamber than the plasma exposure step.

[0074] The term "aspect ratio" refers to the ratio of the height of a groove (or hole) to the width of the groove (or the diameter of the hole).

[0075] The terms "passivating (passivating) chemical", "passivating (passivating) chemical", "passivating (passivating) or passivation) molecule" refer to molecules that condense, chemically adsorb or chemically react with a surface to form a protective layer. Depending on the mechanism involved in the passivation, the passivating layer can be a monolayer or multiple molecular layers in thickness. The passivating molecules herein have a boiling point of 20°C or higher.

[0076] As used herein, the term "vaporization temperature" refers to the temperature at which the inactive molecule vaporizes at a reduced pressure compared to atmospheric pressure or at a pressure different from atmospheric pressure. The vaporization temperature is the boiling point of the inactive molecule at atmospheric pressure.

[0077] It is noted herein that the terms "film" and "layer" may be used interchangeably. It is understood that a film may correspond to or be associated with a layer, and a layer may refer to a film. Furthermore, one of ordinary skill in the art will recognize that the terms "film" or "layer" as used herein refer to a certain thickness of a material laid or spread over a surface and that the surface may range from as large as an entire wafer to as small as a trench or line.

[0078] It is noted herein that the terms “aperture,” “via,” “hole,” and “trench” may be used interchangeably to refer to an opening formed in a semiconductor structure.

[0079] As used herein, the abbreviation “NAND” refers to a Negative AND or Not AND gate; the abbreviation “2D” refers to a 2-dimensional gate structure on a planar substrate; and the abbreviation “3D” refers to a 3-dimensional or vertical gate structure in which gate structures are stacked in a vertical direction.

[0080] It should be noted that in this document, the terms "etching gas" and "etchant" can be used interchangeably when the etching gas is in a gaseous state at room temperature and ambient pressure. It should be understood that the etching gas can correspond to or be related to the etchant, and the etchant can refer to the etching gas.

[0081] The term "dope" or "doping" is used interchangeably in the process of incorporating one or more elements into a film by various methods that can chemically or physically combine the element, as well as the process of intentionally combining atoms of different elements into the film composition. The one or more elements can be interstitially doped or substitutionally doped within the film.

[0082] Standard abbreviations for the elements of the Periodic Table of the Elements are used herein. It should be understood that elements may be referred to by these abbreviations (e.g., Si refers to silicon, N refers to nitrogen, O refers to oxygen, C refers to carbon, H refers to hydrogen, F refers to fluorine, etc.).

[0083] Unique CAS Registry Numbers (or "CAS") assigned by the Chemical Abstract Service are provided to identify specific molecules disclosed.

[0084] As used herein, the term "hydrocarbyl" refers to a saturated or unsaturated functional group containing only carbon and hydrogen atoms. As used herein, the term "alkyl" refers to a saturated functional group containing only carbon and hydrogen atoms. Alkyl is a type of hydrocarbyl. In addition, the term "alkyl" refers to a straight chain, branched chain or cyclic alkyl group. Examples of straight chain alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, etc. Examples of branched chain alkyl groups include, but are not limited to, tert-butyl. Examples of cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl, etc.

[0085] In this article, the scope can be expressed as from about one specific value and / or to about another specific value. When expressing such a scope, it should be understood that another embodiment is from this specific value and / or to this other specific value, together with all combinations within the scope. Any and all scopes listed herein include their endpoints (that is, x=1 to 4, or the range of x is 1 to 4, including x=1, x=4 and x=any number in the middle), whether or not the term "inclusive" is used.

[0086] References herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described with respect to the embodiment may be included in at least one embodiment of the invention. The phrase "in one embodiment" appearing in different places in the specification does not necessarily all refer to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term "implementation".

[0087] As used in this application, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as superior or advantageous over other aspects or designs. Rather, the use of the word exemplary is intended to present concepts in a concrete manner.

[0088] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise or clear from the context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied in any of the foregoing instances. Furthermore, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from the context to direct to a singular form.

[0089] "Comprising" in the claims is an open transition term, which means that the subsequently identified claim elements are a non-exclusive list (i.e., anything else may be additionally included and remain within the scope of "comprising"). "Comprising" is defined herein to necessarily encompass the more restrictive transition terms "consisting essentially of" and "consisting of"; thus, "comprising" may be replaced by "consisting essentially of" or "consisting of" and remain within the clearly defined scope of "comprising".

[0090] "Providing" in the claims is defined to mean supplying, supplying, making available, or preparing something. Steps may instead be performed by any actor in the absence of explicit language in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] For a further understanding of 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 like elements are given the same or similar reference numerals, and in which:

[0092] FIG. 1A shows an exemplary patterned structure of an oxide hole pattern on a Si substrate or wafer before a mask is opened;

[0093] FIG. 1B shows an exemplary patterned structure of an oxide hole pattern on a Si substrate or wafer after the mask is opened;

[0094] Figure 2 is a flow chart of an exemplary embodiment of the disclosed etching method;

[0095] FIG. 3A shows the use of SiH in a HAR dielectric etch process. 2 I 2 Non-plasma etching applications;

[0096] FIG. 3B shows the use of fluorocarbon etching gas C in a HAR dielectric etching process. 4 F 6 Plasma etching applications;

[0097] FIG. 3C shows an oxide hole pattern formed in a substrate by non-plasma formation of a surface protection layer and plasma etching of holes; and

[0098] FIG. 3D shows an oxide hole pattern formed in a substrate without plasma formation to remove the surface protection layer. DETAILED DESCRIPTION

[0099] An etching method is disclosed, which includes using passivating molecules that condense, chemically adsorb or chemically react with the surface of a substrate to form a surface protection layer without using plasma before the plasma etching step. The disclosed method includes a plurality of steps performed by alternately switching steps 1) and 2), wherein step 1) is to form a surface protection layer on the substrate by exposing the substrate to the vapor of the passivating molecules for a certain period of time under non-plasma conditions; and step 2) is to use an etching gas or a reactive reagent (such as a fluorocarbon or hydrofluorocarbon etching gas) and one or more oxidants to perform plasma dry etching on the substrate on which the surface protection layer is formed. The surface protection layer may or may not be a polymer layer and may or may not be washed with existing cleaning methods. An additional cleaning step may be added at the end of step 2) to clean the surface of the substrate with existing cleaning methods known in the art. The cleaning method may include, but is not limited to, such as using O 2 or CF 4 A plasma cleaning step, or a wet cleaning method involving reagents such as solvents, water or HF. The specific time period in step 2) can range from 0.01 seconds to 10,000 seconds, but is not limited thereto, and until the surface passivation layer of step 1) is removed. If necessary, these steps can be cycled. The number of cycles is not limited, and the cyclic process can be completed until the surface protection layer is completely etched. Between the steps in the cycle, a purge step or a vacuum step using a vacuum pump to the process pressure or the base pressure of the vacuum pump can be applied. These steps are performed sequentially, rather than simultaneously. Step 1) and step 2) are not performed simultaneously.

[0100] The disclosed passivating molecules have a boiling point greater than 20°C or greater than room temperature. The process temperature in step 1) can be less than the boiling point of the passivating molecules. The process temperature in step 2) can range from -50°C to 50°C, preferably at room temperature or 20°C, which makes the entire process easy to control and commercially cheap. The process temperature in step 1) can be the same as the process temperature in step 2).

[0101] The disclosed passivating molecules may include fluorocarbon or hydrofluorocarbon molecules (e.g., C x H a F y, x=1-6, a=0-7, y=0-10), substitutents, and organic or inorganic Si-containing deposition precursors.

[0102] The passivating molecules disclosed can be halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons.

[0103] More specifically, the disclosed passivating molecules having a boiling point greater than 20° C. may be as follows.

[0104] A) Halogen-containing silane, SiR x F y I z , where x+y+z=4; 0≤y≤4; 0≤z≤4; R is selected from H, C 1 -C 10 Straight-chain, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted, amino- and nitrogen-containing alkyl, C 3 -C 10 Cyclic, heterocyclic, aromatic, amino and nitrogen-containing alkyl groups. When x>1, the R terminals can also be connected to form a cyclic group.

[0105] Examples of known compounds of this class include:

[0106]

[0107]

[0108]

[0109] Some of the above exemplary molecules with CAS # and boiling points are shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] The disclosed passivating molecule with a boiling point greater than 20°C is SiH 2 I 2 Diiodosilane (DIS, CAS#: 13760-02-6, boiling point: 150°C).

[0114] B) Hydrofluorocarbons, C x H y F z , where 3≤x≤10; 0≤y≤21; 0≤z≤21; C 3 -C 10The alkyl group may be linear, branched or cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted.

[0115] Examples of known compounds of this class include: C 4 H 2 F 6 , cis-1,1,2,2,3,4-hexafluorocyclobutane, CAS#: 22819-47-2, boiling point: 63°C.

[0116]

[0117] C) containing I hydrofluorocarbons, C n H x F y I z , boiling point greater than 20°C, where 1≤n≤10, 0≤x≤21, 0≤y≤21, and 1≤z≤4. 1 -C 10 The alkyl group may be linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted. 3 -C 10 The alkyl radical may be cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted.

[0118] Examples of known compounds of this class include:

[0119]

[0120]

[0121] D) containing N-hydrofluorocarbons, C n H x F y N z , boiling point greater than 20°C, where 1≤n≤10, 0≤x≤21, 0≤y≤21, and 1≤z≤4. 1 -C 10 The alkyl group may be linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted. 3 -C 10 The alkyl radical may be cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted.

[0122] E) S-containing hydrofluorocarbons, C n H x F y S z, boiling point greater than 20°C, where 1≤n≤10, 0≤x≤21, 0≤y≤21, and 1≤z≤4. 1 -C 10 The alkyl group may be linear, branched, saturated or unsaturated, partially or fully fluorinated, substituted or unsubstituted. 3 -C 10 The alkyl radical may be cyclic, saturated or unsaturated, aromatic, heterocyclic, partially or fully fluorinated, substituted or unsubstituted.

[0123] The disclosed etching method using passivating molecules includes multiple steps performed by alternately switching between non-plasma etching steps with passivating molecules and plasma etching steps with etching gases or reactive reagents. The disclosed etching method allows the exploration of the unique properties of passivating molecules, which have been demonstrated in deposition processes, such as forming a surface protection layer (or passivation layer) in an etching process. The etching gas or reactive reagent is preferably a fluorocarbon or hydrofluorocarbon gas having the following general formula: C x H y F z , where x = 1-6, y = 0-3, z = 1-10. The etching gas or reactive reagent may also contain other elements, such as I, N, O, S, Br. The preferred fluorocarbon etching gas is C 1 -C 6 Fluorocarbon (C x F y ), such as CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 4 F 10 , C 5 F 8 , or C 6 F 6 The preferred hydrofluorocarbon etching gas is C 1 -C 6 Hydrofluorocarbons (C x H a F y , where a>0), such as CH 3 F, CH 2 F 2 , CHF 3 , C 2 H 5 F.C3 H 7 F.C 4 H 2 F 6 , C 3 H 2 F 6 , or C 2 HF 5 molecular.

[0124] In the disclosed method, the dose of the passivating molecules in the non-plasma etching step can be controlled by the chamber pressure and the exposure time. The electrostatic chuck (ESC) temperature of the plasma etching step may affect the etching performance, while the effect of the electrostatic chuck temperature of the non-plasma step is less obvious. When the passivating molecules condense on the surface, the ESC temperature window of the non-plasma etching step is less than the vaporization temperature of the passivating molecules (under a pressure less than atmospheric pressure in this article), preferably the same as the temperature of the plasma step. The ESC temperature window of the plasma step can be room temperature or 20°C. With advanced ESC temperature control capabilities, a wider ESC temperature range is possible. Depending on the thickness of the desired surface protection layer, an ESC temperature below the vaporization temperature of the passivating molecules can cause the passivating molecules to adhere or condense on the surface. Alternatively, another option is that the dose of the passivating molecules in the non-plasma etching step is achieved at a temperature that may be higher than the vaporization temperature of the passivating molecules, which is sufficient to cause the passivating molecules to chemically adsorb or chemically react with the surface of the substrate. In this case, the passivating molecules can be bonded to the surface in a monolayer in the first layer (i.e., the protective layer or passivation layer) for surface protection. The chemical reaction between the passivation molecule and the surface can be, for example, a Si-O, Si-OH, Si-N, etc. bond between the passivation molecule and the surface. The subsequent etching step can be a cleaning step for removing the passivation layer, as shown in FIG. 3D , which can be, for example, using an exemplary gas such as O 2 or CF 4 A plasma etch step is used to remove the passivation layer. Since the process pressure is < 1 atm, the boiling point itself (defined at 1 atm) is not the determining factor whether true condensation will occur, but rather some probability that the molecules will impinge on the surface and have a mechanism of adsorption or chemisorption to the surface.

[0125] Figure 2It is a flow chart of an exemplary embodiment of the disclosed etching method with passivation molecules. First, in step 402, a wafer with one or more layers (e.g., one or more silicon-based layers) and a patterned mask layer disposed on the one or more layers is placed in an etching chamber (i.e., a reactor or a reaction chamber) of a plasma etcher, and the etching chamber is pumped to a high vacuum. Here, the reactor can be an etcher of plasma etching, reactive ion etching, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), remote plasma, pulsed plasma, or ECR plasma. Preferably, the reactor is a CCP plasma etcher. The pressure of the etching chamber can vary from 0.001 Torr to 1000 Torr. Preferably, the pressure of the etching chamber can vary from 1 mTorr to 1 Torr. The pressure of the passivation non-plasma step can be different from the pressure of the plasma etching step. The patterned mask layer can be formed with reference to Figures 1A and 1B. The patterned mask layer can be an amorphous carbon layer or a silicon material layer with an doping element selected from B, N, Si, Al, Cr, Ti, or W. In step 404, the wafer is clamped to an electrostatic chuck (ESC), the ESC temperature is set and the ESC temperature is balanced. The temperature in the non-plasma etching step can vary from -150°C to 100°C, preferably -50°C to 50°C. The temperature in the non-plasma etching step can be less than the boiling point of the passivation molecule. In step 406, the passivation molecule gas is flowed or introduced into the etching chamber, and the chamber pressure or process pressure is set and maintained for a certain exposure time, preferably the certain exposure time range is 0.01 seconds to 10000 seconds, more preferably 1 second to 30 seconds, so that the passivation molecules condense and / or absorb on the wafer surface to form a surface protection layer or a surface passivation layer. Here, an inert gas can be introduced into the etching chamber together with the passivation molecule gas, that is, the passivation molecule gas and the inert gas (Ar, Ne, Kr, Xe, N 2 ) is introduced into the etching chamber. The process may be a physical condensation or a chemical surface reaction to form a modified layer (such as a protective layer) on the surface of the wafer. The flow rate of the passivating molecular gas may vary from 1 sccm to 10000 sccm, preferably from 100 sccm to 1000 sccm. If an inert gas (Ar, Ne, Kr, Xe, N 2 ), then passivating molecules and inert gases (Ar, Ne, Kr, Xe, N 2) can vary from 1 sccm to 10000 sccm, preferably from 100 sccm to 1000 sccm. These flow rates will depend on the characteristics of the molecules and the chamber configuration and size. After a certain exposure time, in step 408, stop the passivation molecule gas or the passivation molecule and the inert (e.g., Ar, Ne, Kr, Xe) gas mixture flowing into the etching chamber, the residual gas mixture in the etching chamber is evacuated and the etching chamber is pumped to a high vacuum. The chamber pressure and exposure time can control the flow rate or dose of the passivation molecule in the above-mentioned non-plasma etching process. In the next step 410, the plasma etching process begins. In the case of an ESC temperature different from the ESC temperature in step 404, the ESC temperature is set and allowed to balance. The ESC temperature in the plasma etching process can be the same as the ESC temperature in the non-plasma etching process set in step 404. The ESC temperature range in the plasma etching process can be -150°C to 50°C, preferably room temperature or 20°C. In step 412, one or more etching gases, such as fluorocarbons or hydrofluorocarbons (e.g., C x H y F z , x=1-6, a=0-7, y=0-10) etching gas flows or is introduced into the etching chamber and is balanced, and optionally inert (e.g., Ar, Ne, Kr, Xe) gas and etching gas flow into the etching chamber and are balanced. Preferred fluorocarbon gases are selected from CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 4 F 10 , C 5 F 8 , or C 6 F 6 One or more C 1 -C 6 C x F y Molecules. Preferred hydrofluorocarbon gases are selected from CH 3 F, CH 2 F 2 , CHF 3 , C 2 H 5 F.C 3 H 7 F.C4 H 2 F 6 , C 3 H 2 F 6 , or C 2 HF 5 One or more C 1 -C 6 C x H a F y molecule (where a>0). The flow rate of the fluorocarbon or hydrofluorocarbon etching gas can vary from 1 sccm to 10000 sccm, preferably from 10 sccm to 100 sccm. In the next step, step 414, the plasma source power is turned on to ignite the plasma; the bias power is turned on to set the plasma bias. The plasma process is then kept running for a specified time, preferably a specified exposure time of 0.01s to 10000s, more preferably 0.01s to 30s. The source plasma power can vary from 10W to 20000W, preferably from 100W to 3000W. The bias plasma power can vary from 10W to 100,000W. The source plasma can be in a continuous mode or a pulsed mode, wherein the pulse frequency is 1Hz to 10000Hz, preferably 100Hz to 1000Hz. The bias plasma can be in a continuous mode or a pulsed mode, wherein the pulse frequency is 1Hz to 10000Hz. In this step, the etching gas is plasma activated. The plasma activated etching gas performs plasma dry etching on one or more layers in the wafer, thereby forming holes on the patterned mask layer in one or more layers. After the plasma process runs for a specified exposure time, all plasma source powers are turned off in step 416. The gas in the etching chamber is then evacuated, and the etching chamber is pumped to a high vacuum. Afterwards, the wafer is released from the ESC in step 418, and the wafer is transferred out of the etching chamber in step 420. If necessary, steps 404 to 418 can be cycled until the desired etching depth of the hole is achieved and a surface protection layer is also formed on the sidewall of the hole. Here, the specific exposure time of the non-plasma etching process in each subsequent cycle and the specified exposure time of the plasma dry etching process can be modified. Additional steps may be required to remove the surface protection layer or any other passivation chemical from the surface of the wafer. These cleaning steps may involve plasma or wet processes. The plasma process may include processes such as O 2 or CF 4 Wet processes can include water, organic solvents, or acids such as HF.

[0126] Any of the above steps can be performed in static or dynamic mode. Static mode means that the gas flows into the closed reaction chamber, that is, the gate valve on the closed reaction chamber is closed. Dynamic mode means that the gas flows dynamically in the vacuum etching chamber, wherein the gate valve of the vacuum pump is opened.

[0127] The enclosed reaction chamber can be any enclosure or chamber within a device in which an etching process is performed, such as and not limited to reactive ion etching (RIE), capacitively coupled plasma (CCP) with a single or multiple frequency RF source, inductively coupled plasma (ICP), or microwave plasma reactors, or other types of etching systems capable of selectively removing a portion of a silicon-containing film or generating reactive species. One of ordinary skill in the art will recognize that different plasma reaction chamber designs provide different electronic temperature controls. Suitable commercially available plasma reaction chambers include, but are not limited to, those sold under the trademark eMAX TM Applied Materials' magnetically enhanced reactive ion etcher, sold under the trademark Flex TM Lam Research sells the Lam Research Dual CCP Reactive Ion Etcher Dielectric Etch Product Family. With such a plasma reaction the RF power in the chamber can be pulsed to control the plasma characteristics and thereby further improve the etching performance (selectivity and damage).

[0128] Alternatively, the plasma treated reactants can be generated outside the reaction chamber. A reactive gas generator may be used to treat the reactants prior to introduction 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 reactants O 2 Can be decomposed into two O · Preferably, the remote plasma may be generated with a power ranging from about 1 kW to about 10 kW, more preferably from about 2.5 kW to about 7.5 kW.

[0129] The reaction chamber may contain one or more than one substrate. For example, the reaction chamber may contain 1 to 200 silicon wafers having a diameter of 25.4 mm to 450 mm. The substrate may be any suitable substrate used in the manufacture of semiconductor, photovoltaic, flat panel or LCD-TFT devices. Examples of suitable substrates include wafers such as silicon, silicon dioxide, glass, Ge, SiGe, GeSn, InGaAs, GaSb, InP, or GaAs wafers. From the 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, Ga, In, Sn, Sb, Bi 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), Ge, SiGe, GeSn, InGaAs, GaSb, InP; mask layer materials such as amorphous carbon with or without dopants, anti-reflective coatings, photoresist materials, metal oxides (such as AlO, TiO, HfO, ZrO, SnO, TaO, etc.) or metal nitride layers (such as AlN, ZrN, SnN, HfN, titanium nitride, tantalum nitride, etc.) or combinations thereof; etch stop layer materials (such as silicon nitride, polycrystalline silicon, crystalline silicon, silicon carbide, SiON, SiCN or combinations thereof), device channel materials (such as crystalline silicon, epitaxial silicon, doped silicon, Si a O b H c C d N e (where a>0; b, c, d, e≥0)) or a combination thereof. The silicon oxide layer may 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 under the trade names Black Diamond II or III by Applied Materials. In addition, layers containing tungsten or a noble metal (e.g., platinum, palladium, rhodium, or gold) may be used. In addition, examples of these silicon-containing films may be Si a O b H c C d N e (where a>0; b, c, d, e≥0) Throughout the specification and claims, the wafer and any associated layers thereon are referred to as a substrate.

[0130] The vapor of the disclosed passivating molecule and the vapor of fluorocarbon or hydrofluorocarbon are introduced into the reaction chamber containing the substrate and the silicon-containing film deposited thereon, respectively. 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 of ordinary skill in the art will recognize that the flow rate can vary from tool to tool.

[0131] The vapors of the disclosed passivating molecules and the vapors of fluorocarbons or hydrofluorocarbons can be used in pure form or in admixture with an inert gas such as N 2 , Ar, Kr, Ne, He, Xe, etc.) or a blend of solvents. The vapor of the disclosed passivating molecule and the vapor of the fluorocarbon may be present in the blend at different concentrations.

[0132] Furthermore, the disclosed passivating molecules and fluorocarbon or hydrofluorocarbon etching gases are delivered in purities ranging from 95% to 99.999% by volume and can be used to remove CO, CO 2 、N 2 , H 2 O, HF, H 2 S. SO 2 , halides and other hydrocarbons or hydrohalocarbons by known standard purification techniques.

[0133] An inert gas may also be introduced into the reaction chamber to maintain the plasma in step 2). The fluorocarbon or hydrofluorocarbon inert gas may be He, Ar, Xe, Kr, Ne, N 2 , He or a combination thereof. Before being introduced into the chamber, the etching gas and the inert gas may be mixed, wherein the inert gas accounts for between about 0.01% v / v and about 99.9% v / v of the resulting mixture. Alternatively, the inert gas may be introduced into the chamber continuously, while the etching gas is introduced into the chamber in pulses.

[0134] In step 2), the vapor of fluorocarbon or hydrofluorocarbon etching gas and the inert gas are plasma activated to produce an activated etching gas. The plasma decomposes the etching gas into free radical forms (i.e., activated etching gas). Plasma can be generated by applying RF or DC power. Plasma can be generated with RF power in the range of about 25W to about 100,000W. Plasma can be generated remotely or in the reactor itself. Plasma can be generated under RF applied at two electrodes in dual-frequency CCP or ICP mode. The RF frequency of plasma can be in the range of 100KHz to 1GHz. Different RF sources of different frequencies can be coupled at the same electrode and applied. Plasma RF pulses can be further used to control molecular splitting and reactions at the substrate. Those skilled in the art will recognize methods and equipment suitable for such plasma treatment.

[0135] A quadrupole mass spectrometer (QMS), optical emission spectrometer, FTIR or other free radical / ion measurement tool can measure the activated etching gas from the chamber exhaust to determine the type and number of species generated. If necessary, the flow rate of the etching gas and / or the inert gas can be adjusted to increase or decrease the number of free radical species generated.

[0136] The disclosed passivation molecules and fluorocarbon or hydrofluorocarbon etching gases can be mixed with other gases before or in the reaction chamber, respectively. Preferably, the gases can be mixed before being introduced into the chamber to provide a uniform concentration of the incoming gas.

[0137] In another alternative, vapor of the disclosed passivating molecules and vapor of a fluorocarbon or hydrofluorocarbon etchant gas may be introduced into the chamber separately from the other gases, such as when two or more gases are reactive or more easily delivered separately.

[0138] In another alternative, the disclosed vapor of the passivating molecule and the inert gas, and the vapor of the fluorocarbon or hydrofluorocarbon etching gas and the inert gas, respectively, are the only two gases used during the etching process. Here, the disclosed vapor of the passivating molecule and the vapor of the fluorocarbon or hydrofluorocarbon etching gas, respectively, may or may not be mixed with the inert gas.

[0139] Exemplary other gases include, but are not limited to, oxidants such as O 2 , O 3 ,CO,CO 2 、NO、N 2 O、NO 2 , H 2 O, H 2 O 2 , COS, SO 2The disclosed vapor of the passivating molecule and the oxidant, and the vapor of the fluorocarbon or hydrofluorocarbon etching gas and the oxidant can be mixed together before being introduced into the reaction chamber.

[0140] Alternatively, the oxidant may be introduced into the chamber continuously, and the vapor of the disclosed passivating molecule and the vapor of the fluorocarbon or hydrofluorocarbon etching gas may be introduced into the chamber in pulses. The oxidant may comprise between approximately 0.01% v / v to about 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).

[0141] The silicon-containing film reacts with the activated fluorocarbon or hydrofluorocarbon etching gas to form volatile byproducts, which are removed from the reaction chamber. The aC mask, anti-reflective 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.

[0142] The reaction between the silicon-containing film and the activated etching gas results in anisotropic removal of the silicon-containing film from the substrate. Atoms of nitrogen, oxygen and / or carbon may also be present in the silicon-containing film. The removal is attributed to physical sputtering of the silicon-containing film by plasma ions (accelerated by the plasma) and / or conversion of Si into volatile species such as SiF by chemical reactions of plasma species. x , where x is in the range of 1-4.

[0143] The disclosed etching method with alternating non-plasma and plasma processes preferably exhibits high selectivity to the mask and etches through oxide layers or alternating layers of SiO and SiN, thereby producing a vertical etch profile without bowing or roughness, which is important for 3D NAND applications. In addition, the plasma-activated vapor deposits a surface protection layer on the sidewalls to minimize feature profile deformation. For other applications, such as DRAM and 2D NAND, for example, the plasma-activated etching gas 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, W, Ru, etc.; or from channel regions or polysilicon regions composed of SiGe.

[0144] The disclosed etching method with alternating non-plasma and plasma processes produces holes in silicon-containing films, such as channel holes, gate trenches, stepped contacts, capacitor holes, contact holes, contact etching, slit etching, self-aligned contacts, self-aligned vias, super vias, etc. The resulting holes can have an aspect ratio ranging from about 1:1 to about 500:1, preferably about 20:1 to about 400:1; and a diameter ranging from about 5nm to about 500nm, preferably less than 100nm. For example, one of ordinary skill in the art will recognize that the channel hole etching produces holes in silicon-containing films with an aspect ratio greater than 50:1.

[0145] A typical material to be etched may be SiO. The process of etching SiO may be related to etching trenches in borophosphosilicate glass (BPSG), tetraethyl orthosilicate (TEOS) or low deposition rate TEOS (LDTEOS). The etching stop layer may be silicon nitride or silicon oxynitride (SiON) or polysilicon. The mask material used may be aC, p-Si, or a photoresist material. Here, the disclosed iodine-containing etching compound is applied to etch SiO, SiN, p-Si and / or aC substrate films.

[0146] The dielectric layer in the wafer to be etched may include SiN, SiO 2 , SiC, SiCN, SiON. The mask layer material can be amorphous carbon (aC) or silicon material doped with other elements (such as B, N, Si, Al, Cr, Ti and W). Fluorocarbon or hydrofluorocarbon gas can be a series of C x H y F z Molecules, wherein X = 1-6, Y = 0-3, Z = 1-10, wherein the fluorocarbon or hydrofluorocarbon molecule may also contain other elements, such as I, N, O, S, Br. 2 or different oxygen sources (such as CO, CO 2 ,NO,NO 2 、N 2 O) is added to the etching chamber at a flow rate of 1 sccm to 10000 sccm to control the polymerization of the etching step.

[0147] Using the disclosed method, the etching selectivity of dielectric materials (such as SiO) to aC mask can be improved by more than 20%; the etching selectivity of multi-layer SiO / SiN ONON layer to aC mask can be improved by more than 10%. In addition, the advantages of the disclosed method can include improving the etching profile during HAR dielectric etching. The profile bending can be reduced under certain conditions.

[0148] Examples

[0149] The following non-limiting examples are provided to further illustrate embodiments of the present invention. However, these examples are not intended to be all-inclusive and are not intended to limit the scope of the invention described herein.

[0150] The disclosed method has been tested on a commercial dual CCP plasma etch tool using a passivated SiH 2 I 2 (Boiling point: 150°C) Used for oxide hole pattern wafer etching.

[0151] Wafer Information: An exemplary patterning structure for forming an oxide hole pattern on a Si substrate or wafer is shown in Figures 1A and 1B. Figure 1A shows the patterning structure before the mask is opened. SiO 2 The layer 106 is disposed on the Si substrate 108. The aC mask layer 104 is disposed on the SiO 2 The SiON resist layer 102 is disposed on the mask layer 104. FIG. 1B shows that after the mask is opened, the mask opening 110 is formed in the mask layer 104 in the pattern structure. In one embodiment of the following example, the thickness of the SiON resist layer 102 is 100 nm; the SiON mask layer 104 is 700 nm; and the SiO 2 Layer 106 is 3 μm; mask openings 110 range from 140 nm to 160 nm.

[0152] The following etching experiments were conducted on commercially available SiO 2 The hole pattern was performed on a wafer with 3 μm SiO on a Si substrate. 2 layer, and on top is a 641 nm aC mask with a hole CD of 164 nm before etching.

[0153] Example 1: Using SiH 2 I 2 Forming a surface protective layer

[0154] This example is to form a surface protection layer on the wafer surface by adsorption or physical condensation of passivating molecules before plasma etching. More specifically, the surface protection layer is formed by adsorption or physical condensation of passivating molecules on the wafer surface before plasma etching. 2 I 2 The adsorption or physical condensation of (DIS or diiodosilane) forms a thin surface layer on the wafer surface.

[0155] FIG. 3A shows the use of SiH in a HAR dielectric etch process. 2 I 2 As shown in the figure, step 1: forming a surface protection layer on the patterned mask layer. 2 I 2The Ar / Ar mixture flows into the etching chamber or the dual CCP plasma etching tool, and the wafer is exposed to the etching chamber for a certain period of time. No source and bias plasma are added to the etching chamber. The ESC temperature of this non-plasma etching step is set. Then, after a specific time (such as 60, 120 or 180 seconds, etc.), a surface protection layer 202 is formed on the patterned mask layer 204, and the surface protection layer can be a surface condensation layer or a surface reaction layer formed on the patterned mask layer 204. Here, a portion of the surface protection layer 202 is formed on the SiO2 having the mask layer pattern. 2 The layer 206 is formed on the substrate.

[0156] FIG. 3B shows the use of a fluorocarbon etching gas C in a HAR dielectric etching process after forming a surface protection layer on the patterned mask layer. 4 F 6 As shown in the figure, step 2: using fluorocarbon etching gas C 4 F 6 Plasma etching is performed. In this step, an oxidant (e.g., O 2 ) and an inert gas (e.g., Ar) are added to the fluorocarbon etching gas C 4 F 6 In this step, a plasma source and bias plasma are added to the etching chamber and run for a specific time, such as but not limited to 60, 120, 180 seconds. Fluorocarbon etching gas C 4 F 6 flows into the etching chamber and etches the surface protection layer 202 on the SiO 2 The portion directly above the layer 206 and further etches the SiO 2 layer 206, thereby forming a SiO 2 Deep holes 210 are formed in layer 206 .

[0157] Here, if necessary, step 1 and step 2 can be cycled or run alternately until the SiO 2 The desired deep holes 210 are formed in the layer 206. The specific running time of these two steps can be modified in each step in the subsequent cycle. Between each step, that is, between step 1 and step 2 and between step 2 and step 1, there can be a purging step using an inert gas or using a vacuum pump to the process pressure or the base pressure of the pump.

[0158] FIG. 3C shows that SiH 2 I 2 Non-plasma-formed surface protective layer and C 4 F 6The plasma etches the oxide hole pattern formed in the patterned structure on the Si substrate 208. During this process, the formation of the surface protection layer and the SiO 2 The etching of layer 206 is carried out in a cycle so that the SiO 2 A surface protection layer 212 is formed on the sidewalls of the hole 210 in the layer 206. The formation of the surface protection layer 212 and the SiO 2 The etching of layer 206 is not performed simultaneously. SiO 2 The surface protection layer 212 on the sidewall of the hole 210 in the layer 206 is continuously grown downward from the surface protection layer 202 on the patterned mask layer 204, wherein the processes of step 1 and step 2 are alternately performed until a deep hole 210 having the surface protection layer 212 is formed, such as Figure 3c Afterwards, a plasma etch cleaning step may be applied to remove the protective layers 202 and 212, as shown in FIG3D.

[0159] The disclosed method was tested on oxide hole pattern wafers under different conditions. The conditions of step 1 of the non-plasma exposure process were adjusted to observe the profile (e.g., CD, bow, etc.) and selectivity. Variables including ESC temperature, chamber pressure, and exposure time of the non-plasma exposure process and the characteristics of the oxide hole pattern are listed in Tables 3 and 4, respectively. The conditions of step 1 of the non-plasma exposure process adjusted for decoupling ESC in step 1 and step 2 are shown in Tables 5 and 6. Between step 1 and step 2, the chamber was evacuated with a vacuum pump.

[0160] Table 3

[0161]

[0162] Table 4

[0163]

[0164] Table 5

[0165]

[0166] Table 6

[0167]

[0168] In the disclosed method, the dosage of the chemical in the non-plasma etching step can be controlled by the chamber pressure and the exposure time. That is, the chamber pressure can range from 20 mTorr to 400 Torr; and the exposure time of the non-plasma etching step can be <120s. Excessive dosage may cause the top portion of the mask hole to neck (i.e., 110 in FIG. 1B ). The ESC temperature window of the non-plasma etching step can be less than that of the SiH 2 I 2The boiling point of the plasma step is preferably the same as the plasma step - step 2. The ESC temperature window of the plasma step can be room temperature or 20°C, and a wider range may be possible through advanced ESC temperature control capabilities. The disclosed method improves the etching profile and selectivity to the mask.

[0169] Examples of selected conditions for the non-plasma / plasma step are shown in Table 7. The results of the cycles of the non-plasma / plasma step are shown in Table 8.

[0170] Table 7

[0171]

[0172] Table 8

[0173]

[0174] *One loop represents the round trip path of step 1 and step 2.

[0175] **2 loops represent two round trip paths of step 1 and step 2.

[0176] And so on.

[0177] Example 2. SiH in a non-plasma step 2 I 2 With CHF 3 Comparison examples between

[0178] CHF was tested under the same conditions (5 cycles, 60 seconds each, as shown in Table 8) 3 (boiling point -82.1°C) as SiH 2 I 2 The control samples are also used as references for the prior art US 20210020450A1. In these tests, the ESC temperature was set to 20°C. 2 I 2 Differently, when CHF is used before the plasma etching step is introduced 3 When the wafer samples were exposed to the etch chamber (150 sccm, 200 mTorr, 60 s), no improvement in etch selectivity was observed for the aC mask. 3 When the ESC temperature is set to 20°C, CHF 3 The molecules may not attach to the wafer sample surface to form a surface reaction layer or a surface protection layer. Therefore, it is believed that the disclosed method may not be applicable to low boiling point molecules (i.e., molecules having a boiling point below 20° C.). More specifically, the disclosed method may be effective only when the boiling point of the etching gas used in the non-plasma etching step is greater than the process temperature in the non-plasma step, as shown in FIG. 3A .

[0179] As SiH 2 I 2 With CHF 3 Table 9 shows the direct comparison between CHF and ESC at 20°C. 3 As can be seen from the direct comparison, when SiH 2 I 2 When the selectivity is 5.7 (without SiH 2 I 2 The baseline continuous etching process) was improved to 7.3 (non-plasma, cyclic etching), where CHF was used in the non-plasma cyclic etching step. 3 When , the selectivity is essentially unchanged relative to the baseline continuous etch process (6.8 vs. 7.0, respectively).

[0180] Table 9

[0181]

[0182] Although the subject matter described herein can be described in the context of illustrative implementations to process one or more computing application features / operations of a computing application having a user interaction component, the subject matter is not limited to these specific embodiments. Rather, the techniques described herein can be applied to any suitable type of user interaction component execution management method, system, platform, and / or device.

[0183] It should be understood that many additional changes in the details, materials, steps and arrangements of parts described and illustrated herein to explain the essence of the present invention may be made by those skilled in the art within the principles and scope of the present invention as expressed in the appended claims. Therefore, the present invention is not intended to be limited to the specific embodiments in the examples and / or drawings given above.

[0184] Although embodiments of the present invention have been shown and described, those skilled in the art may modify them without departing from the spirit or teachings of the present invention. The embodiments described herein are exemplary only and not restrictive. Many variations and modifications of the compositions and methods are possible and within the scope of the present invention. Therefore, the scope of protection is not limited to the embodiments described herein, but is limited only by the subsequent claims, the scope of which shall include all equivalents of the subject matter of the claims.

Claims

1. A method for forming a hole pattern in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method The following steps are involved: 1) exposing the substrate to vapor of passivating molecules for a period of time under non-plasma conditions to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas, and plasma dry etching the substrate with the plasma-activated etching gas to form holes on the patterned mask layer in the film; and 3) Repeating steps 1) to 2) until the desired hole pattern is formed in the membrane, Wherein the surface protection layer is also formed on the side walls of the holes formed in the membrane.

2. The method according to claim 1, in, The vaporization temperature of the passivation molecules is greater than the process temperature in step 1).

3. The method according to claim 2, in, The process temperature in step 1) is the same as the process temperature in step 2).

4. The method according to claim 2, in, The process temperature in step 1) ranges from -150°C to 100°C.

5. The method according to claim 3, in, The process temperature in step 2) ranges from -150°C to 50°C.

6. The method according to claim 3, in, The process temperature in step 2) is 20°C.

7. The method according to any one of claims 1 to 3, in, The passivating molecule has a boiling point equal to or greater than 20°C.

8. The method according to any one of claims 1 to 3, in, The passivating molecule is selected from the group consisting of halogen-containing silanes, hydrofluorocarbons, I-containing hydrofluorocarbons, N-containing hydrofluorocarbons, and S-containing hydrofluorocarbons.

9. The method according to any one of claims 1 to 3, in, The passivating molecule is SiH 2 I 2 .

10. The method according to any one of claims 1 to 3, in, The passivating molecule is selected from Ar, N 2 , Xe, Kr, Ne, or a combination thereof.

11. The method according to any one of claims 1 to 3, in, The etching gas has the formula: C x H y F z , where x=1-6, y=0-3, z=1-10.

12. The method according to any one of claims 1 to 3, in, The etching gas is selected from CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 4 F 10 , C 5 F 8 or C 6 F 6 C 1 -C 6 Fluorocarbon gas, or selected from CH 3 F, CH 2 F 2 , CHF 3 , C 2 H 5 F.C 3 H 7 F.C 4 H 2 F 6 , C 3 H 2 F 6 or C 2 HF 5 C 1 -C 6 Hydrofluorocarbon gas.

13. The method according to any one of claims 1 to 3, in, The process pressure in step 1) ranges from 0.001 Torr to 50 Torr.

14. The method according to any one of claims 1 to 3, in, The time period in step 1) varies from 0.01 seconds to 10000 seconds.

15. The method according to any one of claims 1 to 3, in, The plasma process time in step 2) varies from 0.01 seconds to 10,000 seconds.

16. The method according to any one of claims 1 to 3, in, The film is SiO 2 , SiN, SiC, SiCN, or SiON layers, or alternating SiO / SiN or SiO / p-Si layers.

17. The method of any one of claims 1 to 3, further comprising: 2 ,CO,CO 2 ,NO,NO 2 、N 2 An oxidant of O is added to the plasma-activated etching gas, wherein the oxidant is plasma-activated.

18. A method for forming a hole pattern in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on an oxide layer, the method include: 1) exposing the substrate to a gas of passivating molecules for a certain period of time under non-plasma conditions to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated etching gas, and performing plasma dry etching on the substrate with the plasma-activated etching gas to form holes on the patterned mask layer in the oxide layer; and 3) Repeating steps 1) to 2) until a desired oxide hole pattern is formed in the oxide layer, wherein the surface protection layer is also formed on the sidewalls of the holes in the oxide layer.

19. The method of claim 18, in, The vaporization temperature of the passivation molecules is greater than the process temperature in step 1).

20. A method of forming a hole pattern in a substrate, the substrate comprising a film disposed thereon and a patterned mask layer disposed on the film, the method include: 1) Expose the substrate to SiH 2 I 2 vapor for a certain period of time to form a surface protection layer on the patterned mask layer; 2) exposing the substrate to a plasma-activated fluorocarbon or hydrofluorocarbon etching gas, and plasma dry etching the substrate with the plasma-activated fluorocarbon or hydrofluorocarbon etching gas to form holes on the patterned mask layer in the film; and 3) Repeating steps 1) to 2) until a desired hole pattern is formed in the film, wherein the surface protection layer is also formed on the sidewalls of the holes in the film.

Images