Etching compositions

Abstract

The present disclosure is directed to etching compositions that are useful for, e.g., selectively removing a boron phosphorus glass (BPSG) film from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.

Description

[0001] ETCHING COMPOSITIONS

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] The present application claims priority to U.S. Provisional Application Serial No. 63 / 535,328, filed on August 30, 2023, the contents of which are hereby incorporated by reference in their entirety.

[0004] FIELD OF THE DISCLOSURE

[0005] The present disclosure relates to etching compositions and processes of using etching compositions. In particular, the present disclosure relates to etching compositions that can selectively etch boron phosphorus glass (BPSG) films in the presence of silicon oxide layers.

[0006] BACKGROUND OF THE DISCLOSURE

[0007] The semiconductor industry is rapidly decreasing the dimensions and increasing the density of electronic circuitry and electronic components in microelectronic devices, silicon chips, memory chips, liquid crystal displays, MEMS (Micro Electro Mechanical Systems), printed wiring boards, and the like. The integrated circuits within them are being layered or stacked with insulating layers having constantly decreasing thicknesses between each circuitry layer. As the feature sizes have shrunk, patterns have become smaller, and device performance parameters tighter and more robust. As a result, various issues which heretofore could be tolerated can no longer be tolerated or have become more of an issue due to the smaller feature size.

[0008] In the construction of semiconductor devices, boron phosphorus glass (BPSG) films frequently need to be etched. In the various types of uses and device environments other layers are in contact with or otherwise exposed at the same time as BPSG is etched. Highly selective etching of BPSG in the presence of these other materials (e.g., metal conductors, dielectrics, channel materials, gate materials, and hard masks) is typically needed for device yield and long life. SUMMARY OF THE DISCLOSURE

[0009] The present disclosure relates to compositions and processes for selectively etching BPSG films relative to hard mask layers, gate materials (e.g., SiGe, or SiOx) and / or low-k dielectric layers (e.g., SiOx, carbon doped oxide, SiCO, or silicon oxycarbonitride (SiOCN)) that are often present in a semiconductor device. More specifically, the present disclosure relates to compositions and processes for selectively etching BPSG relative to SiOx and / or SiOCN.

[0010] In some embodiments, the disclosure provides etching compositions, including: a) hydrofluoric acid; b) at least one fluorine-containing compound other than hydrofluoric acid, wherein the at least one fluorine-containing compound includes a fluoroborate compound, a fluorine-containing inorganic acid, or a salt thereof; c) at least one organic solvent selected from water soluble alcohols, water soluble ketones, water soluble esters, and water soluble ethers; and d) water.

[0011] In some embodiments, the fluorine-containing compound is a fluoroborate compound.

[0012] In some embodiments, the fluoroborate compound includes a cation and a fluoroborate anion of formula (I): (R2)xB(F)4-x‘ (I), wherein R2is substituted or unsubstituted C1-C10 alkyl, or R2is substituted or unsubstituted aryl, and x is 0, 1 , 2, or 3.

[0013] In some embodiments, the fluoroborate anion of formula (I) has the formula R2B(F)3‘, in which R2is substituted or unsubstituted C1-C10 alkyl, or R2is substituted or unsubstituted aryl. In some embodiments, R2is C1-C10 alkyl optionally substituted by a substituted or unsubstituted aryl, or R2is aryl optionally substituted by a substituted or unsubstituted C1-C10 alkyl, halo, nitro, or C1-C10 alkoxy.

[0014] In some embodiments, the fluoroborate compound is tetrafluoroboric acid or a tetrafluoroborate salt.

[0015] In some embodiments, the fluoroborate compound is ammonium tetrafluoroborate or a quaternary ammonium tetrafluoroborate salt.

[0016] In some embodiments, the fluoroborate compound is tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, or tetrabutylammonium tetrafluoroborate.

[0017] In some embodiments, the fluoroborate compound is ammonia trifluoroborate.

[0018] In some embodiments, the at least one fluorine-containing compound includes a fluorine-containing inorganic acid or a salt thereof.

[0019] In some embodiments, the at least one fluorine-containing inorganic acid or a salt thereof includes hexafluorosilicic acid, methylpentafluorosilicic acid, ammonium hexafluorosilicate, hexafluorophosphoric acid, ammonium hexafluorophosphate, hexafluorotitanic acid, or hexafluorozirconic acid.

[0020] In some embodiments, the at least one fluorine-containing compound is in an amount of from about 0.001 wt% to about 0.5 wt% of the composition.

[0021] In some embodiments, the at least one organic solvent includes an alkylene glycol or alkylene glycol ether. In some embodiments, the at least one organic solvent is in an amount of from about 90 wt% to about 99 wt% of the composition.

[0022] In some embodiments, the water is in an amount of from about 0.1 wt% to about 10 wt% of the composition.

[0023] In some embodiments, the disclosure provides methods for selectively removing a boron phosphorus glass (BPSG) film in the presence of a silicon oxide layer. Such methods can be performed, for example, by contacting a semiconductor substrate containing a BPSG film and a silicon oxide layer with the composition of the disclosure to substantially remove the BPSG film.

[0024] In some embodiments, the disclosure provides methods wherein a pattern is formed on a surface of the semiconductor substrate and the BPSG film is a part of the pattern.

[0025] In some embodiments, the methods do not substantially remove the silicon oxide layer.

[0026] In some embodiments, the disclosure provides articles formed by the methods of the disclosure, wherein the article is a semiconductor device.

[0027] In some embodiments, the semiconductor device is an integrated circuit.

[0028] DETAILED DESCRIPTION OF THE DISCLOSURE

[0029] As defined herein, unless otherwise noted, all percentages expressed should be understood to be percentages by weight to the total weight of the composition. Unless otherwise noted, ambient temperature is defined to be between about 16 and about 27 degrees Celsius (°C). As used herein, the terms “layer” and “film” are used interchangeably. In general, the disclosure features an etching composition (e.g., an etching composition for selectively removing BPSG) that includes (e.g., comprises or consists of) a) hydrofluoric acid; b) at least one fluorine-containing compound other than hydrofluoric acid, wherein the at least one fluorine-containing compound includes a fluoroborate compound, a fluorine-containing inorganic acid, or a salt thereof; c) at least one organic solvent selected from water soluble alcohols, water soluble ketones, water soluble esters, and water soluble ethers; and d) water.

[0030] In some embodiments, the hydrofluoric acid contained in the etching compositions described herein can be in an amount that, in combination with the other materials of the etching composition, provides desired etching performance (e.g., desired BPSG etch rate and selectivity). Without wishing to be bound by theory, it is believed that the hydrofluoric acid can facilitate the removal of BPSG films on a semiconductor substrate during the etching process and enhance the BPSG etch selectivity.

[0031] In some embodiments, the hydrofluoric acid is present in the etching compositions described herein in an amount of at least about 0.001 wt% (e.g., at least about 0.002 wt%, at least about 0.004 wt%, at least about 0.005 wt%, at least about 0.006 wt%, at least about 0.008 wt%, at least about 0.01 wt%, at least about 0.02 wt%, at least about 0.04 wt%, or at least about 0.05 wt%) to at most about 0.1 wt% (e.g., at most about 0.08 wt%, at most about 0.06 wt%, at most about 0.05 wt%, at most about 0.04 wt%, at most about 0.02 wt%, at most about 0.01 wt%, at most about 0.008 wt%, at most about 0.006 wt%, or at most about 0.005 wt%). The hydrofluoric acid can be added to the compositions of the disclosure as an approximately 49% aqueous solution.

[0032] In some embodiments, the etching composition of this disclosure can include at least one (e.g., two, three, or four) fluorine-containing inorganic acid or a salt thereof. The fluorine-containing inorganic acid described herein can be an inorganic acid containing an inorganic element such as silicon, phosphorus, boron, titanium, or zirconium. The salt of the fluorine-containing inorganic acid can be an ammonium salt (e.g., a tetraalkylammonium salt). Examples of suitable fluorine-containing inorganic acids or salts thereof include hexafluorosilicic acid, methylpentafluorosilicic acid, ammonium hexafluorosilicate, hexafluorophosphoric acid, ammonium hexafluorophosphate, tetrafluoroboric acid, hexafluorotitanic acid, hexafluorozirconic acid, tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, and tetrabutylammonium hexafluorophosphate. Without wishing to be bound by theory, it is believed that the fluorine-containing inorganic acid or a salt thereof can facilitate the removal of BPSG films and inhibit the removal of other dielectric materials (e.g., silicon oxide (SiOx) and silicon oxycarbonitride (SiOCN)) on a semiconductor substrate during the etching process, thereby enhancing the BPSG etch selectivity (e.g., the BPSG / SiOCN and / or BPSG / SiOx etch selectivity).

[0033] In some embodiments, the at least one fluorine-containing inorganic acid or a salt thereof contained in an etching composition described herein can be in an amount that, in combination with the other materials of the etching composition, provides desired etching performance, including desired silicon nitride etch rate and selectivity. For example, the at least one fluorine-containing inorganic acid or a salt thereof can be in an amount of at least about 0.001 wt% (e.g., at least about 0.002 wt%, at least about 0.004 wt%, at least about 0.005 wt%, at least about 0.006 wt%, at least about 0.008 wt%, at least about 0.01 wt%, at least about 0.02 wt%, at least about 0.04 wt%, or at least about 0.05 wt%) to at most about 0.5 wt% (e.g., at most about 0.4 wt%, at most about 0.2 wt%, at most about 0.05 wt%, at most about 0.04 wt%, at most about 0.02 wt%, at most about 0.01 wt%, at most about 0.008 wt%, at most about 0.006 wt%, or at most about 0.005 wt%) of an etching composition described herein.

[0034] In some embodiments, the compositions of this disclosure employ a fluoroborate compound. Fluoroborate compounds contemplated include compounds having a suitable cation (e.g., FT) and a fluoroborate anion of the formula (R2)xB(F)4-x- in which R2is substituted or unsubstituted C1-C10 alkyl, or R2is substituted or unsubstituted aryl, and wherein x is 0, 1 , 2, or 3. In some embodiments, R2is C1-C10 alkyl optionally substituted by a substituted or unsubstituted aryl, or R2is aryl optionally substituted by a substituted or unsubstituted Ci-C alkyl, halo, nitro, or Ci-C alkoxy.

[0035] In some embodiments, the fluoroborate compounds contain a tetrafluoroborate or a trifluoroborate anion and a suitable cation. In such embodiments, when x is 0, the compound can be fluoroboric acid or a tetrafluoroborate salt. In some embodiments, tetrafluoroborate salts include those with substituted or unsubstituted ammonium cations (e.g., ammonium cation and quaternary ammonium cations such as tetramethylammonium, tetraethylammonium, and N,N-diethyl-N-methyl-(2- methoxyethyl)ammonium). Alkali metal (e.g., Li, Na, or K) tetrafluoroborate salts could also be employed.

[0036] In some embodiments, the compositions can include a fluoroborate anion of the formula R2B(F)3‘, in which R2is substituted or unsubstituted alkyl (e.g., arylalkyl) or R2is substituted or unsubstituted aryl.

[0037] Examples of suitable cations include, but are not limited to, substituted or unsubstituted ammonium cations (e.g., ammonium and quaternary ammonium cations such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, and N,N- diethyl-N-methyl-(2-methoxyethyl)ammonium). Alkali metal (e.g., Li, Na, or K) tetrafluoroborate salts could also be employed.

[0038] Examples of alkyl, aryl, or arylalkyl trifluoroborate anion include, but are not limited to, phenyltrifluoroborate, chlorophenyltrifluoroborate, fluorophenyltrifluoroborate, methylphenyltrifluoroborate, trifluoromethylphenyltrifluoroborate, methyltrifluoroborate and benzyltrifluoroborate. Examples of specific alkyl, aryl, or arylalkyl trifluoroborate salts include, but are not limited to, the combinations of the ammonium and quaternary ammonium cations listed above with the alkyl, aryl, or arylalkyl trifluoroborate listed anions.

[0039] In some embodiments, the compositions of this disclosure include at least about 0.001 wt% (e.g., at least about 0.002 wt%, at least about 0.004 wt%, at least about 0.005 wt%, at least about 0.006 wt%, at least about 0.008 wt%, at least about 0.01 wt%, at least about 0.02 wt%, at least about 0.04 wt%, or at least about 0.05 wt%) to at most about 0.5 wt% (e.g., at most about 0.4 wt%, at most about 0.2 wt%, at most about 0.05 wt%, at most about 0.04 wt%, at most about 0.02 wt%, at most about 0.01 wt%, at most about 0.008 wt%, at most about 0.006 wt%, or at most about 0.005 wt%) of the fluoroborate compound.

[0040] In general, the etching composition of this disclosure can include water as a solvent. In some embodiments, the water can be de-ionized and ultra-pure, contain no organic contaminants, and / or have a minimum resistivity of about 4 to about 17 mega Ohms or at least about 17 mega Ohms. In some embodiments, the water is in an amount of from at least about 0.1 wt% (e.g., at least about 0.2 wt%, at least about 0.3 wt%, at least about 0.4 wt%, at least about 0.5 wt%, or at least about 0.6 wt%) to at most about 10 wt% (e.g., at most about 9 wt%, at most about 7 wt%, at most about 5 wt%, at most about 3 wt%, or at most about 1 wt%) of the etching composition.

[0041] The etching composition described herein can optionally include at least one (e.g., two, three, or four) oxidizing agent. Examples of suitable oxidizing agents include periodic acid, perchloric acid, and hydrogen peroxide.

[0042] In some embodiments, the at least one oxidizing agent can be from at least about 0.1 wt% (e.g., at least about 0.2 wt%, at least about 0.3 wt%, at least about 0.4 wt%, at least about 0.5 wt%, at least about 0.6 wt%, at least about 0.7 wt%, at least about 0.8 wt%, at least about 0.9 wt%, or at least about 1 wt%) to at most about 5 wt% (e.g., at most about 4.5 wt%, at most about 4 wt%, at most about 3.5 wt%, at most about 3 wt%, at most about 2.5 wt%, at most about 2 wt%, at most about 1.5 wt%, at most about 1 wt%, at most about 0.9 wt%, at most about 0.8 wt%, at most about 0.7 wt%, at most about 0.6 wt%, or at most about 0.5 wt%) of the etching composition of this disclosure. Without wishing to be bound by theory, it is believed that the oxidizing agent can facilitate and enhance the removal of BPSG films on a semiconductor substrate. In some embodiments, the etching composition of this disclosure can be substantially free of an oxidizing agent. In some embodiments, the etching composition of this disclosure can include at least one (e.g., two, three, or four) organic solvent. In some embodiments, the organic solvent can be a water soluble organic solvent. As defined herein, a “water soluble” substance (e.g., a water soluble organic solvent) refers to a substance having a solubility of at least 1 % by weight in water at 25°C. In some embodiments, the organic solvent can be selected from the group consisting of water soluble alcohols (e.g., alkane diols or glycols such as alkylene glycols), water soluble ketones, water soluble esters, and water soluble ethers (e.g., glycol ethers). Examples of suitable organic solvents include glycerol, propylene glycol, hexylene glycol, 1 ,3-propanediol, ethylene glycol butyl ether, 3-methoxy-3-methyl-1 -butanol, acetone, cyclohexanone, ethyl acetate, and propylene glycol monoethyl ether acetate.

[0043] In some embodiments, the at least one organic solvent can be from at least about 90 wt% (e.g., at least about 91 wt%, at least about 92 wt%, or at least about 93 wt%) to at most about 99 wt% (e.g., at most about 98 wt%, at most about 97 wt%, or at most about 96 wt%) of the etching composition.

[0044] In some embodiments, the etching composition of this disclosure can have a pH of at least about 0 (e.g., at least about 0.2, at least about 0.4, at least about 0.5, at least about 0.6, at least about 0.8, at least about 1 , at least about 1 .2, at least about 1 ,4, or at least about 1 .5) and / or at most about 2 (e.g. , at most about 1.8, at most about 1.6, at most about 1 .5, at most about 1 .4, at most about 1 .2, at most about 1 , at most about 0.8, at most about 0.6, or at most about 0.5). Without wishing to be bound by theory, it is believed that an etching composition having a pH lower than 0 would cause significant corrosion to other materials on a substrate. Further, without wishing to be bound by theory, it is believed that an etching composition having a pH higher than 2 would not have a sufficient BPSG removal rate.

[0045] In some embodiments, the cleaning compositions of this disclosure can optionally include at least one (e.g., two, three, or four) pH adjusting agent (e.g., an acid or a base) to control the pH to from about 0 to about 2. The amount of the pH adjusting agent required, if any, can vary as the concentrations of the other components (e.g., the quaternary ammonium hydroxide and the acid) are varied in different formulations. In some embodiments, the pH adjusting agent can be at least about 0.1 wt% (e.g., at least about 0.2 wt%, at least about 0.4 wt%, at least about 0.5 wt%, at least about 0.6 wt%, at least about 0.8 wt%, at least about 1 wt%, at least about 1 .2 wt%, at least about 1 .4 wt%, or at least about 1.5 wt%) and / or at most about 3 wt% (e.g., at most about 2.8 wt%, at most about 2.6 wt%, at most about 2.5 wt%, at most about 2.4 wt%, at most about 2.2 wt%, at most about 2 wt%, or at most about 1 .8 wt%) of the etching composition. In some embodiments, the etching composition of this disclosure can be substantially free of a pH adjusting agent.

[0046] In some embodiments, the pH adjusting agent is free of a metal ion (except for a trace amount of metal ion impurities). Suitable metal ion free pH adjusting agents include acids and bases. Suitable acids that can be used as a pH adjusting agent include organic acids (e.g., carboxylic acids) and inorganic acids. Exemplary carboxylic acids include, but are not limited to, monocarboxylic acids, bicarboxylic acids, tricarboxylic acids, o-hydroxyacids and |3-hydroxyacids of monocarboxylic acids, a- hydroxyacids or [3-hydroxyacids of bicarboxylic acids, or a-hydroxyacids and [3- hydroxyacids of tricarboxylic acids. Examples of suitable carboxylic acids include citric acid, maleic acid, fumaric acid, lactic acid, glycolic acid, oxalic acid, tartaric acid, succinic acid, and benzoic acid. Examples of suitable inorganic acids include phosphoric acid, nitric acid, sulfuric acid, and hydrochloric acid. Suitable acids also include sulfonic acids such as methanesulfonic acid.

[0047] Suitable bases that can be used as a pH adjusting agent include ammonium hydroxide, monoamines (including alkanolamines), and cyclic amines. Examples of suitable monoamines include, but are not limited to, triethylamine, tributylamine, tripentylamine, diethylamine, butylamine, dibutylamine, and benzylamine. Examples of suitable alkanolamines include, but are not limited to, monoethanolamine, diethanolamine, triethanolamine, and aminopropyldiethanolamine. Examples of suitable cyclic amines include, but are not limited to, 1 ,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1 ,5-diazabicyclo[4.3.0]-5-nonene (DBN), and octahydro-2H-quinolizine.

[0048] In some embodiments, the etching composition of the present disclosure can contain additives such as pH adjusting agents, corrosion inhibitors, surfactants, additional organic solvents, biocides, and defoaming agents as optional components. Examples of certain suitable additives include alcohols (e.g., polyvinyl alcohol and sugar alcohols). Examples of suitable defoaming agents include polysiloxane defoamers (e.g., polydimethylsiloxane), polyethylene glycol methyl ether polymers, ethylene oxide / propylene oxide copolymers, and glycidyl ether capped acetylenic diol ethoxylates (such as those described in U.S. Patent No. 6,717,019, herein incorporated by reference). Examples of suitable surfactants include cationic, anionic, nonionic, and amphoteric surfactants.

[0049] In general, the etching composition of the present disclosure can have a relatively high BPSG removal rate. In some embodiments, the etching composition can have a BPSG removal rate of from at least about 10 A / min (e.g., at least about 15 A / min, at least about 20 A / min, at least about 25 A / min, at least about 30 A / min, at least about 35 A / min, or at least about 40 A / min) to at most about 100 A / min (e.g., at most about 90 A / min, at most about 80 A / min, at most about 70 A / min, at most about 60 A / min, or at most about 50 A / min) when a BPSG film is treated by the etching composition at 130°C for one minute.

[0050] In general, the etching composition of the present disclosure can have a relatively low SiOCN removal rate. In some embodiments, the etching composition can have a SiOCN removal rate of from at most about 0.5 A / min (e.g., at most about 0.45 A / min, at most about 0.4 A / min, at most about 0.35 A / min, at most about 0.3 A / min, at most about 0.25 A / min, at most about 0.2 A / min, at most about 0.15 A / min, or at most about 0.1 A / min) to 0 A / min (e.g., at least 0.001 A / min) when a SiOCN film is treated by the etching composition at 130°C for 20 minutes. In general, the etching composition of the present disclosure can have a relatively low SiOx removal rate. In some embodiments, the etching composition can have a SiOx removal rate of from at most about 5 A / min (e.g., at most about 4.5 A / min, at most about 4 A / min, at most about 3.5 A / min, at most about 3 A / min, at most about 2.5 A / min, at most about 2 A / min, at most about 1 .5 A / min, or at most about 1 A / min) to 0 A / min (e.g., at least 0.01 A / min) when a SiOx film is treated by the etching composition at 130°C for 30 minutes.

[0051] In general, the etching composition of the present disclosure can have a relatively high BPSG / dielectric material (e.g., SiOx, or SiOCN) removal rate selectivity (i.e., a high ratio of BPSG removal rate over dielectric material removal rate). In some embodiments, the etching composition can have a BPSG / SiOx removal rate selectivity of at least about 10 (e.g., at least about 20, at least about 40, at least about 50, at least about 60, at least about 80, at least about 100, at least about 150, at least about 200, at least about 250, at least about 300, at least about 350, at least about 400, at least about 450, at least about 500, or at least about 1000) and / or at most about 5000 (e.g., at most about 4000, at most about 3000, at most about 2000, or at most about 1000) when the etch rates of BPSG and SiOx are measured under the same conditions (e.g., at the same etching temperature). In some embodiments, the etching composition can have a BPSG / SiOCN removal rate selectivity of at least about 100 (e.g., at least about 150, at least about 200, at least about 250, at least about 300, at least about 350, at least about 400, at least about 450, at least about 500, at least about 600, at least about 700, at least about 800, at least about 900, or at least about 1000) and / or at most about 5000 (e.g., at most about 4000, at most about 3000, at most about 2000, or at most about 1000) when the etch rates of BPSG and SiOCN are measured under the same conditions (e.g., at the same etching temperature). In some embodiments, as the SiOx and SiOCN etch rates are significantly lower than the BPSG etch rate, the etching times for SiOx and SiOCN are longer than the etching time for BPSG to obtain reliable SiOx and SiOCN etch rates. In such embodiments, the etch rates thus obtained are still considered as measured under the same conditions even though the etching times may be different (when other conditions are the same). In some embodiments, the etching compositions of the present disclosure can be substantially free of one or more of additive components, in any combination, if more than one additive component is present. Such components are selected from the group consisting of organic solvents; polymers (e.g., non-ionic, cationic, or anionic polymers); oxygen scavengers; quaternary ammonium compounds (e.g., salts or hydroxides); alkaline bases (such as NaOH, KOH, LiOH, Mg(OH)2, and Ca(OH)2); surfactants (e.g., cationic, anionic, or non-ionic surfactants); defoamers; fluorine-containing compounds (e.g., fluoride compounds or fluorinated compounds (such as fluorinated polymers / surfactants)) other than fluorine-containing inorganic acids or salts thereof; silicon-containing compounds such as silanes (e.g., alkoxysilanes) other than described herein; nitrogen-containing compounds other than described herein (e.g., amino acids, amines; imines (e.g., amidines such as 1 ,8-diazabicyclo[5.4.0]-7-undecene (DBU) and 1 ,5-diazabicyclo[4.3.0]non-5-ene (DBN)), amides, or imides); abrasives (e.g., ceria abrasives, non-ionic abrasives, surface modified abrasives, negatively / positively charged abrasive, or ceramic abrasive composites); plasticizers; oxidizing agents (e.g., peroxides such as hydrogen peroxide, and periodic acid); corrosion inhibitors (e.g., azole or non-azole corrosion inhibitors); electrolytes (e.g., polyelectrolytes); silicates; cyclic compounds other than described herein (e.g., azoles (such as diazoles, triazoles, or tetrazoles), triazines, and cyclic compounds containing at least two rings such as substituted or unsubstituted naphthalenes, or substituted or unsubstituted biphenylethers); chelating agents; buffering agents; acids such as organic acids (e.g., carboxylic acids such as hydroxycarboxylic acids, polycarboxylic acids, and sulfonic acid) and inorganic acids (e.g., sulfuric acid, sulfurous acid, nitrous acid, nitric acid, phosphorous acid, and phosphoric acid); salts (e.g., halide salts or metal salts); and catalysts (e.g., metal-containing catalysts). In some embodiments, the composition is substantially free of a salt other than a quaternary ammonium salt. As used herein, a component that is “substantially free” from an etching composition refers to an ingredient that is not intentionally added into the etching composition. In some embodiments, the etching composition described herein can have at most about 1000 ppm (e.g., at most about 500 ppm, at most about 250 ppm, at most about 100 ppm, at most about 50 ppm, at most about 10 ppm, or at most about 1 ppm) of one or more of the above components that are substantially free from the etching composition. In some embodiments, the etching compositions described herein can be completely free of one or more of the above components.

[0052] The etching composition of this disclosure can be prepared by simply mixing the components together, or can be prepared by blending two or more compositions (each containing certain components of an etching composition described herein) in a kit.

[0053] In some embodiments, the present disclosure features a method of removing BPSG film in the presence of a silicon oxide layer. The method can include contacting a semiconductor substrate containing a BPSG film with an etching composition described herein to substantially remove the BPSG film. In some embodiments, the semiconductor substrate can include a pattern or a feature on a surface and the BPSG film is a part of the pattern or feature. In some embodiments, the method can further include rinsing the semiconductor substrate with a rinse solvent after the contacting step and / or drying the semiconductor substrate after the rinsing step.

[0054] In some embodiments, the contacting step can be performed at an elevated temperature. For example, the contacting step can performed at a temperature ranging from at least about 110°C (e.g., at least about 115°C, at least about 120°C, at least about 125°C, or at least about 130°C) to at most about 160°C (e.g., at most about 155°C, at most about 150°C, at most about 145°C, at most about 140°C, at most about 135°C, or at most about 130°C). Without wishing to be bound by theory, it is believed that performing the contacting step at an elevated temperature (e.g., in the range described above) can increase the BPSG etch rate of the etching composition.

[0055] In some embodiments, the method does not substantially remove a metal conductor (e.g., Cu) or a dielectric material other than BPSG (e.g., SiOx or SiOCN) in the semiconductor substrate. For example, the method does not remove more than about 5% by weight (e.g., more than about 3% by weight or more than about 1 % by weight) of a metal conductor or a dielectric material in the semiconductor substrate.

[0056] The semiconductor substrates to be etched in this method can contain organic and organometallic residues, and a range of metal oxides, some or all of which may also be removed during the etching process.

[0057] Semiconductor substrates described herein (e.g., wafers) typically are constructed of silicon, silicon germanium, Group lll-V compounds such as GaAs, or any combination thereof. The semiconductor substrates can additionally contain exposed integrated circuit structures such as interconnect features (e.g., metal lines and dielectric materials). Metals and metal alloys used for interconnect features include, but are not limited to, aluminum, aluminum alloyed with copper, copper, titanium, tantalum, cobalt, silicon, titanium nitride, tantalum nitride, and tungsten. The semiconductor substrates can also contain layers of interlayer dielectrics, polysilicon, silicon oxide, silicon nitride, silicon germanium, silicon carbide, titanium oxide, or carbon doped silicon oxides, or any combinations thereof.

[0058] A semiconductor substrate can be contacted with the etching composition by any suitable method, such as placing the etching composition into a tank and immersing and / or submerging the semiconductor substrate into the etching composition, spraying the etching composition onto the semiconductor substrate, streaming the etching composition onto the semiconductor substrate, or any combinations thereof.

[0059] The etching composition of the present disclosure can be effectively used up to a temperature of from at least about 110°C to about 160°C. The etch rates of BPSG increase with temperature in this range, thus the processes at a higher temperature can be run for shorter times. Conversely, lower etching temperatures typically require longer etching times. Etching times can vary over a wide range depending on the particular etching method, thickness, and temperature employed. When etching in an immersion batch type process, a suitable time range is, for example, up to about 10 minutes (e.g., from about 1 minute to about 7 minutes, from about 1 minute to about 5 minutes, or from about 2 minutes to about 4 minutes). Etching times for a single wafer process can range from about 30 seconds to about 60 minutes (e.g., from about 1 minute to about 60 minutes, from about 10 minutes to about 60 minutes, from about 20 minutes to about 60 minutes, or from about 30 minutes to about 60 minutes).

[0060] To further promote the etching ability of the etching composition of the present disclosure, mechanical agitation means can be employed. Examples of suitable agitation means include circulation of the etching composition over the substrate, streaming or spraying the etching composition over the substrate, and ultrasonic or megasonic agitation during the etching process. The orientation of the semiconductor substrate relative to the ground can be at any angle. Horizontal or vertical orientations are preferred.

[0061] Subsequent to the etching, the semiconductor substrate can be rinsed with a suitable rinse solvent for about 5 seconds up to about 5 minutes with or without agitation means. Multiple rinse steps employing different rinse solvents can be employed. Examples of suitable rinse solvents include, but are not limited to, deionized (DI) water, methanol, ethanol, isopropyl alcohol, N-methylpyrrolidinone, gammabutyrolactone, dimethyl sulfoxide, ethyl lactate, and propylene glycol monomethyl ether acetate. Alternatively, or in addition, aqueous rinses with pH>8 (such as dilute aqueous ammonium hydroxide) can be employed. The rinse solvent can be applied using means similar to that used in applying an etching composition described herein. The etching composition may have been removed from the semiconductor substrate prior to the start of the rinsing step or it may still be in contact with the semiconductor substrate at the start of the rinsing step. In some embodiments, the temperature employed in the rinsing step is between 16°C and 27°C. Optionally, the semiconductor substrate is dried after the rinsing step. Any suitable drying means known in the art can be employed. Examples of suitable drying means include spin drying, flowing a dry gas across the semiconductor substrate, or heating the semiconductor substrate with a heating means such as a hotplate or infrared lamp, Maragoni drying, Rotagoni drying, IPA drying, and any combinations thereof. Drying times will be dependent on the specific method employed but are typically on the order of 30 seconds up to several minutes.

[0062] In some embodiments, the etching method described herein further includes forming a semiconductor device (e.g., an integrated circuit device such as a semiconductor chip) from the semiconductor substrate obtained by the method described above.

[0063] The present disclosure is illustrated in more detail with reference to the following examples, which are for illustrative purposes and should not be construed as limiting the scope of the present disclosure.

[0064] EXAMPLE

[0065] GENERAL PROCEDURE 1 Formulation blending

[0066] Samples of etching compositions are prepared by adding, while stirring, to the calculated amount of the solvent the remaining components of the formulation.

[0067] GENERAL PROCEDURE 2

[0068] Materials and Methods

[0069] Blanket film etch rate measurements on films are carried out using commercially available unpatterned 300 mm diameter wafers that are diced into 0.5”x1.0” test coupons for evaluation. Primary blanket film materials used for testing include: 1 ) a BPSG film of about 1000 A thickness deposited on a silicon substrate; and 2) a SiOx film of about 1200 A thickness deposited on a silicon substrate. The blanket film test coupons are measured for pre-treatment and post-treatment thickness to determine blanket film etch rates. For the BPSG and SiOx blanket films, the film thicknesses are measured pre-treatment and post-treatment by Ellipsometry using a Woollam VASE.

[0070] GENERAL PROCEDURE 3 Etching evaluation with beaker test

[0071] All blanket film etch testing is carried out at 75°C in a 600 mL glass beaker containing 200 g of a sample solution with continuous stirring at 250 rpm, with the Parafilm® cover in place at all times to minimize evaporative losses. All blanket test coupons having a blanket film exposed on one side to the sample solution are diced by diamond scribe into 0.5” x 1 .0” square test coupon size for beaker scale testing. Each individual test coupon is held into position using a single 4” long, locking plastic tweezers clip. The test coupon, held on one edge by the locking tweezers clip, is suspended into the 600 mL HDPE beaker and immersed into the 200 g test solution while the solution is stirred continuously at 250 rpm at 25°C. Immediately after each sample coupon is placed into the stirred solution, the top of the 600 mL HDPE beaker is covered and resealed with Parafilm®. The test coupons are held static in the stirred solution until the treatment time (0.5 minutes or 60 minutes) elapses.

[0072] After the treatment time in the test solution elapses, the sample coupons are immediately removed from the 600 mL HDPE beaker and rinsed. Specifically, the coupon is immersed in a 300 mL volume of ultra-high purity deionized (DI) water for 15 seconds with mild agitation, which is followed by immersion in 300 mL of isopropyl alcohol (IPA) for 15 seconds with mild agitation, and a final rinse by immersion in 300 mL of IPA for 15 seconds with mild agitation. After the final IPA rinse step, all test coupons are subjected to a filtered nitrogen gas blow off step using a hand held nitrogen gas blower which forcefully removes all traces of IPA to produce a final dry sample for test measurements. Example 1

[0073] Formulation Example 1 (FE-1 ) is prepared according to General Procedure 1 , and is evaluated according to General Procedures 2 and 3. The formulation of FE-1 is summarized in Table 1 .

[0074] Table 1

[0075] While the invention has been described in detail with reference to certain embodiments thereof, it will be understood that modifications and variations are within the spirit and scope of that which is described and claimed.

Claims

WHAT IS CLAIMED IS:1 . An etching composition, comprising: a) hydrofluoric acid; b) at least one fluorine-containing compound other than hydrofluoric acid, wherein the at least one fluorine-containing compound comprises a fluoroborate compound, a fluorine-containing inorganic acid, or a salt thereof; c) at least one organic solvent selected from the group consisting of water soluble alcohols, water soluble ketones, water soluble esters, and water soluble ethers; and d) water.

2. The composition of claim 1 , wherein the fluorine-containing compound is a fluoroborate compound.

3. The composition of claim 2, wherein the fluoroborate compound comprises a cation and a fluoroborate anion of formula (I): (R2)xB(F)4-x‘ (I), wherein R2is substituted or unsubstituted C1-C10 alkyl, or R2is substituted or unsubstituted aryl, and x is 0, 1 , 2, or 3.

4. The composition of claim 3, wherein the fluoroborate anion is of the formula R2B(F)3‘, in which R2is substituted or unsubstituted C1-C10 alkyl, or R2is substituted or unsubstituted aryl.

5. The composition of claim 3 or 4, wherein R2is C1-C10 alkyl optionally substituted by a substituted or unsubstituted aryl, or R2is aryl optionally substituted by a substituted or unsubstituted Ci-C alkyl, halo, nitro, or Ci-C alkoxy.

6. The composition of claim 2, wherein the fluoroborate compound is tetrafluoroboric acid or a tetrafluoroborate salt.

7. The composition of claim 6, wherein the fluoroborate compound is ammonium tetrafluoroborate or a quaternary ammonium tetrafluoroborate salt.

8. The composition of claim 7, wherein the fluoroborate compound is tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, or tetrabutylammonium tetrafluoroborate.

9. The composition of claim 2, wherein the fluoroborate compound is ammonia trifluoroborate.

10. The composition of claim 1 , wherein the at least one fluorine-containing compound comprises a fluorine-containing inorganic acid or a salt thereof.11 . The composition of claim 10, wherein the at least one fluorine-containing inorganic acid or a salt thereof comprises hexafluorosilicic acid, methylpentafluorosilicic acid, ammonium hexafluorosilicate, hexafluorophosphoric acid, ammonium hexafluorophosphate, hexafluorotitanic acid, or hexafl uorozirconic acid.

12. The composition of any one of claims 1 -11 , wherein the at least one fluorine-containing compound is in an amount of from about 0.001 wt% to about 0.5 wt% of the composition.

13. The composition of any one of claims 1 -12, wherein the at least one organic solvent comprises an alkylene glycol or alkylene glycol ether.

14. The composition of any one of claims 1 -13, wherein the at least one organic solvent is in an amount of from about 90 wt% to about 99 wt% of the composition.

15. The composition of any one of claims 1 -14, wherein the water is in an amount of from about 0.1 wt% to about 10 wt% of the composition.

16. A method for selectively removing a boron phosphorus glass (BPSG) film in the presence of a silicon oxide layer, comprising: contacting a semiconductor substrate containing a BPSG film and a silicon oxide layer with the composition of claim 1 to substantially remove the BPSG film.

17. The method of claim 16, wherein a pattern is formed on a surface of the semiconductor substrate and the BPSG film is a part of the pattern.

18. The method of claim 16 or 17, wherein the method does not substantially remove the silicon oxide layer.

19. An article formed by the method of any one of claims 16-18, wherein the article is a semiconductor device.

20. The article of claim 19, wherein the semiconductor device is an integrated circuit.