Method for improving selective etching of silicon nitride over silicon oxide

Abstract

The invention relates to a method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, more preferably for selectively etching silicon nitride in the presence of silicon oxide.

Description

[0001] The present invention relates to a method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, and more preferably for selectively etching silicon nitride in the presence of silicon oxide. Background of the Invention 3D memory devices are fabricated by vertically alternating stacks of multiple conductive silicon layers and insulating silicon dioxide layers. One fabrication step involves selectively etching sacrificial SiN with an acidic etchant solution containing various additives such as silanes, silicic acid, or unfunctionalized colloidal silica. x layer.

[0003] High selectivity is required in etching to repeatedly remove vertically stacked materials while maintaining the chip structure. Colloidal silica has been proposed as an additive to provide corrosion resistance to the selective etching of silicon oxide by silicon nitride over silicon oxide through the in-situ formation of Si(OH)4, which reversibly inhibits silicon oxide etching according to the Le Chatelier principle.

[0004] However, etching formulations containing typical silica particles typically (i) introduce large silica particles into the etching chamber, which in turn requires expensive filters in the chamber, and (ii) they still lack the required selectivity to minimize semiconductor chip yield loss.

[0005] Various attempts to use silicon oxide and / or silanes in etching formulations for the aforementioned purposes have been reported in the art. However, none of these methods have been established in industrial manufacturing to date.

[0006] JP 2021-015970 teaches a silicon nitride film etching solution for improving the etching selectivity of silicon nitride films relative to silicon oxide films, and a method for manufacturing semiconductor devices using silicon dioxide having amino acid groups, thioester groups or ester groups between colloidal silicon dioxide particles.

[0007] JP 2021-086943 describes the use of a composition of silicon compound and phosphoric acid to selectively etch silicon nitride relative to silicon oxide.

[0008] US 2020 / 0308485 discloses an etching solution for etching silicon nitride. The etching solution comprises: phosphoric acid; tetrafluoroboric acid; a silicon compound; water; and at least one of sulfuric acid and an ionic liquid. The silicon compound optionally comprises silicon dioxide (claim 3, paragraph 31).

[0009] US 2020 / 0216758 discloses an etchant composition and a method for manufacturing a semiconductor device, the composition comprising an inorganic acid; about 0.01 parts by weight to about 0.5 parts by weight of colloidal silica; about 0.01 parts by weight to about 30 parts by weight of an ammonium-based additive; and about 20 parts by weight to about 50 parts by weight of a solvent, all parts by weight being based on 100 parts by weight of the inorganic acid.

[0010] US 2015 / 0111390 relates to a method for selectively removing silicon nitride, comprising: providing a wafer having silicon nitride on a wafer surface; providing a mixture of phosphoric acid and a silicon-containing material; and delivering the mixture to the wafer surface to remove the silicon nitride.

[0011] CN112216607 relates to a silicon nitride film etching solution containing two different types of silicon dioxide particles.

[0012] JP 2020-205320 discloses an additive for silicon nitride etching solutions containing an organoalkali metal silicate and water, and having a content of 1 mg / L or less of Na, K, Ca, Cr, Fe and Cu.

[0013] While silanes or their derived oligomers and polymers have been used in existing technologies, the compatibility of such compounds in etching solutions remains a largely unresolved issue. Many such etching solutions exhibit poor stability and / or lack sufficient processability because they are too viscous or inhomogeneous. It is quite common for such etching solutions containing silanes to become increasingly viscous over time, even to the point of becoming unprocessable, or for precipitation to occur.

[0014] Purpose of the invention Therefore, the object of the present invention is to overcome the shortcomings of the prior art. Another object of the present invention is to provide a method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, more preferably for selectively etching silicon nitride in the presence of silicon oxide. Invention Overview The above objective is achieved by a method according to the invention for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, and more preferably for selectively etching silicon nitride in the presence of silicon oxide, the method comprising the following steps: M1) provides a substrate having at least one surface; and M2) Treat at least one surface of the substrate with a composition comprising the following components. a) At least one acid; b) At least one silica particle; Its features The at least one silica particle is at least partially functionalized with at least one silicon compound selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof.

[0016] The composition according to the method of the invention is advantageously very stable and therefore can be used for a long time.

[0017] The method according to the invention unexpectedly allows for highly selective etching of silicon nitride relative to silicon oxide. Using the method of the invention, silicon nitride can now be selectively removed in the presence of silicon oxide.

[0018] The method according to the invention advantageously allows for improved post-cleaning convenience after its use, thereby achieving a cleaner overall process.

[0019] The method according to the present invention allows for a higher silicon nitride etching rate compared to existing technologies.

[0020] The method according to the invention advantageously works as an etching formulation without requiring any other additives, particularly as an etching formulation for the selective removal of silicon nitride in the presence of silicon oxide.

[0021] Preferred embodiments that particularly well achieve the above objectives are described in the following specification and dependent claims. Invention Details Unless otherwise stated, all percentages throughout this specification are weight percentages (wt% or weight %). Yields are given as a percentage of theoretical yield. Unless otherwise stated, concentrations given in this specification refer to the mass of the entire solution, dispersion, or composition. Room temperature refers to 20°C. Standard pressure refers to 10¹³ mbar. Unless otherwise stated below, experiments were conducted at room temperature and standard pressure. In the context of this invention, "at least one" means one or more, such as two.

[0023] The term "alkyl" according to the present invention includes branched or unbranched alkyl groups comprising cyclic and / or acyclic structural elements, wherein the cyclic structural element of the alkyl group naturally requires at least three carbon atoms. C1-C18 alkyl groups in this specification and claims refer to alkyl groups having 1 to X carbon atoms (X being an integer). C1-C18 alkyl groups include, among others, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, hexyl, heptyl, and octyl, hexadecyl, and octadecyl. Unless otherwise stated below, alkyl groups are generally not substituted.

[0024] The term "alkyldiyl" refers to a corresponding group having two free valences (bonding sites). In the prior art, it is sometimes referred to as "alkylene". The residues described according to the invention contain cyclic and / or acyclic structural elements and may be straight-chain and / or branched. C1-C4 alkyldiyls include, among others, methane-1,1-diyl, ethane-1,2-diyl, ethane-1,1-diyl, propane-1,3-diyl, propane-1,2-diyl, propane-1,1-diyl, butane-1,4-diyl, butane-1,3-diyl, butane-1,2-diyl, butane-1,1-diyl, butane-2,3-diyl. Generally, unless otherwise stated below, the alkyldiyl group is not substituted.

[0025] "Alkenyl" refers to an unsaturated alkyl group containing at least one olefinic (i.e., C=C-double) bond. With necessary modifications, the above detailed description and preferred embodiments of alkyl groups also apply to alkenyl groups.

[0026] The term "aryl" according to the invention refers to a cyclic aromatic hydrocarbon residue, such as phenyl or naphthyl. Unless otherwise stated below, aryl groups are generally unsubstituted. The term "alkanearyl" according to the invention refers to a hydrocarbon group comprising at least one aryl group and at least one alkyl group, such as benzyl and p-tolyl. Bonding of such alkanearyl groups to other moieties can occur via the alkyl or aryl group of the alkanearyl group. With necessary modifications, the above detailed descriptions and preferred embodiments regarding alkyl and aryl groups also apply to alkanearyl groups.

[0027] If more than one residue—an atom, group of atoms, or an entire structural unit—is to be selected from a given group, each residue is selected independently of the others, meaning they can be selected as the same or different members of the group. Bonding sites in some chemical formulas in this document can be indicated by wavy lines (“…”). ”, as is customary in this field.

[0028] Unless technically impractical or otherwise specified, the embodiments and preferred embodiments described with respect to one aspect of the invention, with necessary modifications, are equally applicable to all other aspects thereof. For the sake of brevity, repetitions are omitted.

[0029] The composition used in the method according to the invention comprises (or preferably consists of) the following components. a) At least one acid; b) At least one silica particle; Its features The at least one silica particle is at least partially functionalized with at least one silicon compound selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof.

[0030] The composition used in the method according to the invention comprises at least one acid. The at least one acid may be an inorganic acid or an organic acid. Methanesulfonic acid is preferred as an organic acid. The at least one acid is preferably an inorganic acid. The at least one acid is preferably selected from the group consisting of sulfuric acid, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphoric acid, nitric acid, methanesulfonic acid, and mixtures thereof. The at least one acid is more preferably selected from the group consisting of sulfuric acid, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphoric acid, nitric acid, and mixtures thereof. Particularly preferably, the at least one acid is phosphoric acid.

[0031] The composition preferably contains at least one acid in an amount of 20.0 to 99.9 wt%, more preferably 30.0 to 90.0 wt%, and even more preferably 40.0 to 85.0 wt% based on the total weight of the composition.

[0032] The composition used in the method according to the invention comprises at least one silica particle. The size (d) of the at least one silica particle... 50 Preferably, the size (d) of the at least one silica particle is 1000 nm or smaller. 50 The preferred range is 5 to 500 nm, even more preferably 5 to 200 nm, particularly 10 to 60 nm. The size of the at least one silica particle is measured by dynamic light scattering, preferably using the method described in the experimental section of this disclosure.

[0033] Preferably, 20% or less, more preferably 10% or less, and even more preferably 1% or less of the at least one silica particle in the composition used in the method according to the invention are agglomerated. Ideally, all silica particles are discrete particles, i.e., they do not agglomerate.

[0034] The at least one silica particle comprises silica (SiO2). The at least one silica particle is preferably composed of silica. The shape of the at least one silica particle is not further limited. It can be spherical, cocoon-shaped (preferably with an aspect ratio of 1 to 1.2), hexagonal, or irregular.

[0035] The at least one silica particle is at least partially functionalized with at least one silicon compound. Functionalization means that the at least one silicon compound is bonded to the surface of the at least one silica particle. By bonding to the surface of the at least one silica particle, a layer is formed on the surface of the at least one silica particle. The layer may cover the entire surface of the at least one silica particle or only one or more portions thereof.

[0036] The organofunctional silane is preferably represented by formula (1):

[0037] in R 1 Choose from the group consisting of amino-functionalized alkyl and aryl groups; and each R 2 The group consisting of hydrogen and C1-C4 alkyl groups is selected independently.

[0038] R 1 The aryl group is preferably phenyl. R 1 The alkyl group is preferably a C1-C4 alkyl group, more preferably a methyl group. More preferably, R 1 Selected from the group consisting of phenyl and C1-C4 alkyl groups. Even more preferably, R 1 It is a phenyl group.

[0039] Each R 2 The preferred group consists of free methyl and ethyl groups.

[0040] Particularly preferably, the organofunctional silane is represented by formula (1a):

[0041] Each R 2 The group consisting of methyl and ethyl groups is selected independently.

[0042] The organofunctional siloxane preferably comprises at least one structural unit according to formula (A):

[0043] in R A1 It is an amino-functionalized alkyl group; Each R A2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and n is selected from 0, 1, and 2.

[0044] R A1 The amino-functionalized alkyl group is preferably represented by formula (A-1):

[0045] in Each U is independently a C1-C8 alkyldiyl; Each R A3 and R A4 It is independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and t is selected from 1, 2 and 3.

[0046] Each U is preferably C2-C4 alkyldiyl, more preferably C2-C3 alkyldiyl. Each R A3 and R A4 Preferably, the group consisting of hydrogen and methyl groups is selected, and more preferably, each R A3 and R A4It is hydrogen. n is preferably 1 or 2, more preferably 1.

[0047] R A1 The preferred amino-functionalized alkyl group is selected from , and The group formed by R. A1 More preferably .

[0048] A particularly preferred version of the structural unit is represented by equation (A-2):

[0049] Where R A5 Choose the group consisting of free hydrogen and -CH2-CH2-NH2, and n is selected from 0, 1 and 2.

[0050] Preferably, the organofunctional siloxane comprises at least one structural unit according to formula (B) (in addition to the at least one structural unit according to formula (A)):

[0051] in R B1 Choose from the group consisting of alkyl and alkenyl groups; each R B2 It is independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and p is selected from 0, 1 and 2.

[0052] R B1 Preferably, it is selected from the group consisting of C1-C4 alkyl and vinyl groups. More preferably, R B1 For methyl. Each R B2 Preferably, the group consisting of hydrogen and methyl groups is selected, and more preferably, R is selected. B2 It is hydrogen.

[0053] The ratio of the number of the at least one structural unit according to formula (A) to the number of the at least one structural unit according to formula (B) is preferably in the range of 0.1 to 10, more preferably 0.5 to 5, and even more preferably 1 to 1.

[0054] The at least one structural unit according to formula (A) and the at least one structural unit according to formula (B) (if included in the organofunctional siloxane) preferably constitute at least 50% by weight, more preferably 75% by weight, and even more preferably 90% by weight of the organofunctional siloxane. The organofunctional siloxane is most preferably composed of one or more structural units according to formula (A) and optionally one or more structural units according to formula (B).

[0055] Preferably, the at least one organofunctional siloxane is an oligomer or a polymer. If the at least one organofunctional siloxane is an oligomer or a polymer, an improved crosslinking density of the film obtained from the organofunctional siloxane can be obtained. The oligomer according to the invention comprises (in total) 2 to 4 structural units according to formula (A) and (optionally) (B), and the polymer comprises (in total) at least 5 structural units according to formula (A) and (optionally) (B). Non-limiting examples of oligomers comprising one structural unit according to formula (A) and one structural unit according to formula (B) are described below: .

[0056] Oligomers and polymers typically comprise one or more linear, branched, and cyclic structures (formed by structural units according to formula (A) and / or (B)). If the organofunctional siloxane comprises more than one structural unit according to formula (A) and optionally (B), the structural unit described herein may also be understood as a repeating structural unit.

[0057] As is commonly used in this field, R g -SiO (4-g / 2) It should be understood that the described silicon atom has 4-g oxygen atoms (g is an integer from 0 to 4) and g residues R. The oxygen atoms are bonded to the silicon atom by single bonds, and thus have another substituent, such as a silicon atom of one of the aforementioned units. In the case of this invention, the other silicon atom is preferably a silicon atom of one of the structural units according to formula (A) or (B). If g is 3, then an M unit is present. If g is 2, then a D unit is present. If g is 1, then a T unit is present. If g is 0, then a Q unit is present. This nomenclature is known to those skilled in the art, for example from W. Noll, Chemie und Technologie der Silicone, Verlag Chemie, Weinheim Bergstr., 1960, p. 2 et seqq.

[0058] Preferably, the silicon compound is selected from the group consisting of: i) Organofunctional silanes represented by formula (1):

[0059] in R 1 Choose from the group consisting of C1-C4 alkyl and phenyl groups; and each R 2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; ii) an organofunctional siloxane comprising at least one structural unit according to formula (A) and optionally at least one structural unit according to formula (B); and a mixture thereof.

[0060] The weight of the layer formed by the at least one silicon compound on the surface of the at least one silica particle is preferably 0.1 to 10.0 wt% of the total weight of the at least one silica particle, more preferably 0.5 to 5.0 wt%.

[0061] Preferably, the composition used in the method according to the invention comprises at least one silica particle, the amount of which is 0.1 to 20.0 wt%, more preferably 0.5 to 15.0 wt%, and even more preferably 1.0 to 10.0 wt%, based on the total weight of the composition according to the invention.

[0062] The silica particles comprising at least one of the functionalized compounds used in the composition according to the method of the invention can be obtained by methods known in the art. The silica particles can be synthesized by the Stöber process, for example using tetraalkoxysilanes, bases such as KOH or ammonia, water, and a suitable solvent (e.g., ethanol). Functionalization of the silica particles can be obtained by treating the silica particles with the silicon compound. Functionalization can be carried out in a solvent (e.g., ethanol) using a catalyst (e.g., a base or acid). These methods are well established in the art. Functionalization can be carried out at temperatures from 10 to 50°C.

[0063] The duration of functionalization depends on various factors, such as the temperature used in the process and any catalyst. Suitable durations range from 1 hour to 24 hours.

[0064] The composition used in the method according to the invention preferably comprises at least one surfactant. The preferred surfactant is a (water-soluble) nonionic surfactant. More preferably, the at least one surfactant is selected from the group consisting of polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oil ether, polyoxyethylene C2-C22 alcohol ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, alkylalkanolamides, and mixtures thereof. These surfactants are commercially available under the trade names Dynols and Surfynols.

[0065] Preferably, the composition used in the method according to the invention comprises the at least one surfactant, the amount of which is 0.001 to 5 wt% based on the total weight of the composition according to the invention, more preferably 0.01 to 2.5 wt%, and even more preferably 0.1 to 1 wt%.

[0066] The composition used in the method according to the invention preferably contains at least one solvent. The at least one solvent is preferably selected from the group consisting of water, alcohol, glycol, and mixtures thereof.

[0067] Preferably, the composition used in the method according to the invention comprises the at least one solvent, the amount of which is 0.1 to 50 wt% based on the total weight of the composition according to the invention, more preferably 1 to 30 wt%, and even more preferably 10 to 30 wt%.

[0068] The composition used in the method according to the invention preferably contains at least one fluorine compound. The at least one fluorine compound is preferably selected from the group consisting of ammonium fluoride, tetra(C1-C6 alkyl)ammonium fluoride, hexafluorosilicic acid, ammonium tetrafluoroborate, tetra(C1-C6 alkyl)ammonium fluoride, and tetrafluoroborate.

[0069] Preferably, the composition used in the method according to the invention comprises at least one fluorine compound, in an amount based on the total weight of the composition according to the invention of 0.0002 to 5 wt%, more preferably 0.0005 to 2 wt%, and even more preferably 0.01 to 1 wt%.

[0070] The composition used in the method according to the invention preferably contains at least one polysilicon etching inhibitor. The at least one polysilicon etching inhibitor is preferably selected from linear or branched C8-C16 alkylbenzene sulfonic acids. More preferably, the at least one polysilicon etching inhibitor is selected from the group consisting of octylbenzene sulfonic acid, nonylalkylbenzene sulfonic acid, decylbenzene sulfonic acid, undecylbenzene sulfonic acid, dodecylbenzene sulfonic acid, tridecylbenzene sulfonic acid, tetradecylbenzene sulfonic acid, pentadecanylbenzene sulfonic acid, hexadecylbenzene sulfonic acid, heptadecanylbenzene sulfonic acid, and octadecylbenzene sulfonic acid. As an alternative to the above-mentioned C8-C16 alkylbenzene sulfonic acids, C6-C16 alkyldiphenyl sulfide disulfonic acid and C6-C16 alkyldiphenylamine disulfonic acid can be used.

[0071] Preferably, the composition used in the method according to the invention comprises at least one polysilicon corrosion inhibitor, the amount of which is 0.001 to 5 wt%, more preferably 0.01 to 2 wt%, and even more preferably 0.02 to 0.08 wt%, based on the total weight of the composition according to the invention.

[0072] The composition used in the method according to the invention preferably comprises (or consists of) the following: a) at least one of the acids; b) at least one silica particle; c) the at least one surfactant; d) The at least one solvent; e) the at least one fluorine compound; and f) Optionally, the at least one polysilicon corrosion inhibitor; Its features The at least one silica particle is at least partially functionalized with at least one silicon compound, the at least one silicon compound being selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof.

[0073] In one embodiment of the invention, the composition used in the method according to the invention preferably comprises (or consists of) the following: a) at least one of the acids; b) The at least one silica particle; c) the at least one surfactant; d) The at least one solvent; e) the at least one fluorine compound; and f) Optionally, the at least one polysilicon corrosion inhibitor; Its features The at least one silica particle is at least partially functionalized with at least one silicon compound, the silicon compound being selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof. The at least one silicon compound is selected from the group consisting of an organofunctional silane represented by formula 1a and an organofunctional siloxane containing at least one structural unit according to formula A-2.

[0074] The compositions used in the methods according to the invention can be prepared by standard methods known to those skilled in the art. Preferably, they are prepared by mixing the components of the composition using standard equipment such as a stirrer and a suitable container.

[0075] This invention relates to a method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, and more preferably for selectively etching silicon nitride in the presence of silicon oxide, comprising the following method steps: M1) provides a substrate having at least one of the said surfaces; and M2) Treat at least one surface of the substrate with the above composition.

[0076] An etched surface is obtained by treating at least one surface of the substrate with the above composition. The method of the present invention includes method steps M1 and M2. The method steps are performed in a given order. Optionally, it includes other method steps that are included in the method of the present invention before, between, or after method steps M1 and M2.

[0077] The substrate is preferably a semiconductor substrate, more preferably a combination of a sensor, a memory logic device substrate, and a semiconductor packaging material. Preferred sensors are MEMS (microelectromechanical systems). Memory logic device substrates are particularly RAM, such as CBRAM, ReRAM, PCM, FeRAM, and memory (NAND and DRAM). In the context of this invention, semiconductor packaging materials are—in particular—IC substrates and printed circuit boards.

[0078] The method according to the invention is preferably used for etching silicon nitride. Preferably, silicon nitride and silicon oxide (both) are present on the surface of the substrate. The method advantageously allows for selective etching of one of the silicon nitride and silicon oxide relative to the other, typically silicon nitride relative to silicon oxide.

[0079] The method according to the invention preferably includes an additional method step M1a performed between method steps M1 and M2: M1a) Treating at least one surface of the substrate with at least one pretreatment compound, wherein the at least one pretreatment compound is selected from the group consisting of: - One or more silanes according to formula (X):

[0080] in R X1 It is an organic functional group, R X1 Preferably selected from the group consisting of C1-C4 alkyl and phenyl groups; and each R X2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and - One or more siloxanes comprising at least one structural unit according to formula (Y-1), and optionally, at least one structural unit according to formula (Z) (in addition to the at least one structural unit according to formula (A):

[0081] in R Y1 It is an amino-functionalized alkyl group; each R Y2 It is independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and y is selected from 0, 1, and 2;

[0082] in R Z1 The group is selected from the group consisting of alkyl and alkenyl groups, preferably C1-C4 alkyl, more preferably methyl, n-propyl or isobutyl, and even more preferably isobutyl; Each R Z2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups, preferably from the group consisting of hydrogen and methyl groups, more preferably R Z2 It is hydrogen; and z is selected from 0, 1, and 2.

[0083] The combination of method steps M1a and M2 (i.e., using the above-described composition) produces a synergistic effect (see Examples 2a to 2c in the Experimental Section). The combination of the pretreatment compound and the above-described composition gives a selectivity far greater than that suggested by the sum of the two individual treatments.

[0084] R X1 The aryl group is preferably phenyl. R X1 The alkyl group is preferably a C1-C4 alkyl group, more preferably a methyl group. More preferably, R X1 Selected from the group consisting of phenyl and C1-C4 alkyl groups. Even more preferably, R X1 It is a phenyl group.

[0085] R Y1 The amino-functionalized alkyl group is preferably represented by formula (Y-1):

[0086] in Each V is independently a C1-C8 alkyl diester; Each R X3 and R X4 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and x is selected from 1, 2, and 3.

[0087] Each V is preferably a C2-C4 alkyldiyl, more preferably a C2-C3 alkyldiyl. Each R X3 and R X4 Preferably, the group consisting of hydrogen and methyl groups is selected, and more preferably, each R X3 and R X4 It is hydrogen. y is preferably 1 or 2, more preferably 1. x is preferably 1 or 2, more preferably 1.

[0088] R Y1 The preferred amino-functionalized alkyl group is selected from , and The groups formed, especially R Y1 for .

[0089] In method step M2, at least one surface of the substrate is treated with the above-described composition.

[0090] The temperature in step M2 is preferably 100 to 200°C, more preferably 120 to 180°C, and even more preferably 140 to 170°C.

[0091] There are no further limitations on the duration of method step M2, and those skilled in the art can select an appropriate duration based on routine experiments. Typically, the duration of method step M2 is from 1 second to 360 minutes, preferably from 30 seconds to 240 minutes, and more preferably from 1 minute to 120 minutes, which has proven to be useful.

[0092] Preferably, the method of the present invention includes method step M3 performed after method step M2: M3) The substrate that has been rinsed with water.

[0093] Method step M3 aims to remove any residual components, particularly acids, from the substrate surface of the above composition. Method step M3 reduces the risk of degradation of any residual components on the substrate surface during subsequent manufacturing steps.

[0094] In step M3, the water is preferably deionized water. The temperature of the water in step M3 is preferably 5 to 50°C, more preferably 10 to 30°C. The duration of step M3 is preferably 1 to 120 seconds, more preferably 5 to 30 seconds.

[0095] It is particularly preferred to use R in method step M1a. X1 An organofunctional silane of formula X representing a phenyl group, and using silica particles at least partially functionalized with an organofunctional siloxane comprising at least one structural unit of formula (A) and at least one structural unit of formula (B), wherein R Y1 The amino-functionalized alkyl group is selected from and The groups formed, especially , where R Z1 It is n-propyl or isobutyl.

[0096] Another aspect of the invention relates to the use of the above-described composition for selective etching of silicon nitride, preferably for selective etching of silicon nitride in the presence of silicon oxide.

[0097] A semiconductor substrate treated with the above composition is also disclosed. The semiconductor substrate is preferably selected from the group defined above.

[0098] This invention is further described by the following items: 1. A composition for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, more preferably for selectively etching silicon nitride in the presence of silicon oxide, said composition comprising: a) At least one acid; b) At least one silica particle; The feature is that the at least one silica particle is at least partially functionalized with at least one silicon compound, the silicon compound being selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof.

[0099] 2. The composition according to item 1, characterized in that the organofunctional silane is represented by formula (1):

[0100] in R 1 Choose from the group consisting of amino-functionalized alkyl and aryl groups; and each R 2 The group consisting of hydrogen and C1-C4 alkyl groups is selected independently.

[0101] 3. The composition according to item 1 or 2, characterized in that the organofunctional siloxane comprises at least one structural unit according to formula (A):

[0102] in R A1 It is an amino-functionalized alkyl group; Each R A2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and n is selected from 0, 1, and 2.

[0103] 4. The composition according to item 3, characterized in that the organofunctional siloxane comprises at least one structural unit according to formula (B):

[0104] Where R B1 Choose from the group consisting of alkyl and alkenyl groups; each R B2 It is independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and p is selected from 0, 1 and 2.

[0105] 5. The composition according to item 4, characterized in that the ratio of the number of the at least one structural unit according to formula (A) to the number of the at least one structural unit according to formula (B) is 0.1 to 10, preferably 0.5 to 5, more preferably 1 to 1.

[0106] 6. The composition according to any one of the preceding items, characterized in that the at least one acid is selected from the group consisting of sulfuric acid, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphoric acid, nitric acid, methanesulfonic acid, and mixtures thereof.

[0107] 7. The composition according to item 6, wherein the at least one acid is phosphoric acid.

[0108] 8. The composition according to any one of the preceding items, characterized in that the composition comprises the at least one silica particle in an amount of 0.1 to 20.0 wt%, preferably 0.5 to 15.0 wt%, more preferably 1.0 to 10.0 wt%, based on the total weight of the composition.

[0109] 9. The composition according to any one of the preceding items, characterized in that the composition comprises the at least one acid in an amount of 20.0 to 99.9 wt%, preferably 30.0 to 90.0 wt%, more preferably 40.0 to 85.0 wt%, based on the total weight of the composition.

[0110] 10. The composition according to any one of the preceding items, characterized in that the composition comprises at least one surfactant, at least one solvent, at least one fluorine compound, and optionally, at least one polysilicon corrosion inhibitor.

[0111] 11. A method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, more preferably for selectively etching silicon nitride in the presence of silicon oxide, comprising the following method steps: M1) provides a substrate having at least one of the said surfaces; and M2) Treat at least one surface of the substrate with the composition according to any one of the preceding items.

[0112] 12. The method according to item 11, wherein the substrate is a semiconductor substrate, preferably selected from the group consisting of a storage logic device substrate and a semiconductor packaging material.

[0113] 13. The method according to any one of items 11 or 12, characterized in that silicon nitride and silicon oxide are present on the surface of the substrate.

[0114] 14. Use of the composition according to any one of items 1 to 10 for selective etching of silicon nitride, preferably for selective etching of silicon nitride in the presence of silicon oxide.

[0115] 15. A semiconductor substrate treated with the composition according to any one of items 1 to 10.

[0116] The invention will now be described with reference to the following non-limiting embodiments.

[0117] Example Unless otherwise stated below, the commercial product shall be used in accordance with the technical data sheet available as of the application date of this specification. Unless otherwise stated below, the latest version of the standard shall apply.

[0118] pH value was measured according to DIN EN ISO 10523 (2012).

[0119] The size of the at least one silica particle was measured as follows: 40 μL of colloidal silica solution was dispersed in 1 ml of deionized water in a 1 cm x 1 cm polystyrene cuvette. The cuvette was then placed in a Malvern Zetasizer Ultra dynamic light scattering instrument to measure the Z-mean value of the suspended colloidal silica particles.

[0120] The following silanes and siloxanes were used throughout the experiment: a. Phenylacetoxysilane (hereinafter referred to as silane 1) b. The siloxane prepared as described in Example 1 of US 10,259,832 (hereinafter referred to as siloxane 1). c. The siloxane prepared as described in Example 5 of US 5,629,400 (hereinafter referred to as siloxane 2). Normalized silicon oxide etching rate (referred to as "normalized SiO2" in the table below) x Etching rate” was measured as follows: [Difference in silicon oxide thickness per unit time with silicon compounds] / [Difference in silicon oxide thickness per unit time without silicon compounds] Normalized silicon nitride etch rate (referred to as "normalized SiN" in the table below) x Etching rate” was measured as follows: [Thickness difference of silicon nitride per unit time with silicon compounds] / [Thickness difference of silicon nitride per unit time without silicon compounds] The selectivity ratio (SiN) in the table below x / SiO x () is the quotient of the normalized silicon nitride etch rate divided by the normalized silicon oxide etch rate.

[0121] Selectivity differences (|SiN) x | - |SiO x |) is calculated by subtracting the absolute value of the normalized silicon oxide etch rate from the absolute value of the normalized silicon nitride etch rate.

[0122] Example 1: Silane-functionalized colloidal silica in an etching medium (method of the present invention) Add 20 ml of 20 wt% colloidal silica (size (d) 50 The surface of a 50 nm solution was modified by adding 2 g of a silicon compound (10 wt% colloidal silica solution, see the column titled "Silicon Compound on Colloidal Silica" in Table 1) and stirring overnight at 20 °C. To prepare the etching solution, 0.25 g of functionalized colloidal silica was placed in 4.75 g of 85% phosphoric acid (the concentration of colloidal silica in the etching solution was 1 wt%). The solution was heated to 160 °C, and then a 1 × 3 cm⁻¹ [structure / component] was applied. 2 1×1 cm of wafer strip 2 The area was placed in the etching solution for 1 hour. Afterward, the wafer was removed from the etching solution and then immersed in water to remove any residual etching solution.

[0123] As an alternative, Comparative Examples 1a and 1b were performed using an etching solution that did not contain silica particles. The etching solution in the comparative examples was prepared by mixing 85 wt.% aqueous phosphoric acid solution with the silicon compounds listed in the column titled "Additive Silicon Compounds" in the table below.

[0124] Table 1

[0125] Comparative Examples; Examples of the Invention Clearly, when the composition according to the invention is used, the selectivity of etching is significantly improved (see comparison of Examples 1c and 1d of the invention with Comparative Examples 1a and 1b).

[0126] When only silane is added to the etchant (as in the comparative examples), the selectivity is about three times lower compared to the embodiments of the present invention that use the same compound.

[0127] Example 2: Pre-coated substrate and silane-functionalized colloidal silicon dioxide in etching medium Silica or nitride wafers were placed in an aqueous solution containing 10 wt% silane at 20°C for 24 hours. 20 ml of 20 wt% colloidal silica (size (d)) was then added. 50The surface of a 50 nm solution was modified by adding 2 g of a silicon compound (10 wt% colloidal silica solution, see the column titled "Silicon Compound on Colloidal Silica" in Table 2) and stirring overnight at 20 °C. To prepare the etching solution, 0.25 g of functionalized colloidal silica was placed in 4.75 g of 85% phosphoric acid (the concentration of colloidal silica in the etching solution was 1 wt%). The solution was heated to 160 °C, and a surface-modified wafer with a size of 1 × 1 cm was placed in the etching solution for 1 hour. Afterward, the wafer was removed from the etching solution and immersed in water to remove any residual etching solution.

[0128] Table 2

[0129] Comparative Examples; Examples of the Invention The compositions of the present invention allow for improved etching selectivity of silicon nitride relative to silicon oxide, as can be seen from the data above. Notably, this selectivity is improved compared to the use of unfunctionalized silicon dioxide in etching formulations described in the prior art (compare Comparative Example 2a and Example 2c of the present invention). The data above demonstrate a synergistic effect between the pre-coating and the composition according to the present invention.

Claims

1. A method for etching at least one surface of a substrate, preferably for selectively etching silicon nitride, more preferably for selectively etching silicon nitride in the presence of silicon oxide, comprising the following method steps: M1) provides a substrate having at least one of the said surfaces; and M2) Treat at least one surface of the substrate with a composition comprising the following components: a) At least one acid; b) At least one silica particle; Its features are, The at least one silica particle is at least partially functionalized with at least one silicon compound selected from the group consisting of organofunctional silanes, organofunctional siloxanes, and mixtures thereof.

2. The method according to claim 1, characterized in that, The organofunctional silane is represented by formula (1): in R 1 Choose from the group consisting of amino-functionalized alkyl and aryl groups; and each R 2 The group consisting of hydrogen and C1-C4 alkyl groups is selected independently.

3. The method according to claim 1 or 2, characterized in that, The organofunctional siloxane comprises at least one structural unit according to formula (A): in R A1 It is an amino-functionalized alkyl group; Each R A2 Independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and n is selected from 0, 1, and 2.

4. The method according to claim 3, characterized in that, The organofunctional siloxane comprises at least one structural unit according to formula (B): Where R B1 Choose from the group consisting of alkyl and alkenyl groups; each R B2 It is independently selected from the group consisting of hydrogen and C1-C4 alkyl groups; and p is selected from 0, 1 and 2.

5. The method according to claim 4, characterized in that, The ratio of the number of the at least one structural unit according to formula (A) to the number of the at least one structural unit according to formula (B) is 0.1 to 10, preferably 0.5 to 5, and more preferably 1 to 1.

6. The method according to any one of the preceding claims, characterized in that, The at least one acid is selected from the group consisting of sulfuric acid, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphoric acid, nitric acid, methanesulfonic acid, and mixtures thereof.

7. The method according to claim 6, characterized in that, The at least one acid is phosphoric acid.

8. The method according to any one of the preceding claims, characterized in that, The composition comprises at least one silica particle in an amount of 0.1 to 20.0 wt%, preferably 0.5 to 15.0 wt%, more preferably 1.0 to 10.0 wt%, based on the total weight of the composition.

9. The method according to any one of the preceding claims, characterized in that, The composition comprises at least one acid in an amount of 20.0 to 99.9 wt%, preferably 30.0 to 90.0 wt%, more preferably 40.0 to 85.0 wt%, based on the total weight of the composition.

10. The method according to any one of the preceding claims, characterized in that, The composition comprises at least one surfactant, at least one solvent, at least one fluorine compound, and optionally, at least one polysilicon corrosion inhibitor.

11. The method according to any one of the preceding claims, characterized in that, The substrate is a semiconductor substrate, preferably a combination of a memory logic device substrate and a semiconductor packaging material.

12. The method according to any one of the preceding claims, characterized in that, The silicon nitride and the silicon oxide are present on the surface of the substrate.

13. Use of the composition according to any one of claims 1 to 10 for selective etching of silicon nitride, preferably for selective etching of silicon nitride in the presence of silicon oxide.

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