Etching composition

Abstract

The present disclosure relates to etching compositions that are useful, for example, for selectively removing silicon from semiconductor substrates as an intermediate step in a multi-step semiconductor manufacturing process.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 399,077, filed August 18, 2022, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to etching compositions and processes using the etching compositions. In particular, the present disclosure relates to etching compositions that can selectively etch silicon in the presence of other exposed or underlying materials, such as metal conductors (e.g., copper), gate materials (e.g., SiGe), barrier materials, and insulator materials (e.g., low-k dielectric materials). [Background technology]

[0003] The semiconductor industry is rapidly reducing the dimensions and increasing the density of electronic circuits and components in microelectronic devices, silicon chips, memory chips, liquid crystal displays, MEMS (microelectromechanical systems), printed wiring boards, and the like. The integrated circuits therein are structured in layers or stacks, and the thickness of the insulating layers between each circuit layer continues to shrink. As feature sizes shrink, patterns become smaller and device performance parameters become more stringent and uncompromising. As a result, various issues that were previously acceptable are no longer acceptable or have become increasingly problematic due to the shrinking feature sizes.

[0004] In the fabrication of advanced integrated circuits, both high-k and low-k insulators and a wide array of barrier layer materials have been used to minimize problems and optimize performance associated with increasing density.

[0005] Silicon (Si) can be used in the manufacture of semiconductor devices, liquid crystal displays, MEMS (microelectromechanical systems), printed wiring boards, etc. Silicon often needs to be removed in the presence of other exposed materials in the semiconductor substrate during an etching process. Summary of the Invention

[0006] In the construction of semiconductor devices, silicon (Si) often needs to be etched. In various types of Si applications and device environments, other layers are contacted or otherwise exposed at the same time that this material is etched. Highly selective etching of Si in the presence of these other materials (e.g., metal conductors, dielectrics, channel materials, gate materials, and hard masks) is usually required for device yield and long life.

[0007] The present disclosure relates to compositions and processes for selectively etching Si (e.g., polysilicon) relative to hard mask layers, gate materials (e.g., SiGe, SiN, or SiOx), and / or low-k dielectric layers (e.g., SiN, SiOx, carbon-doped oxide, or SiCO) present in semiconductor devices. More specifically, the present disclosure relates to compositions and processes for selectively etching Si relative to SiOx and / or SiN.

[0008] In one aspect, the disclosure features an etching composition that includes: (1) at least one quaternary ammonium hydroxide or salt thereof; (2) at least one oxidizing agent; (3) at least one acid different from the at least one oxidizing agent; and (4) water; the etching composition is substantially free of activators and organic solvents.

[0009] In another aspect, the disclosure features an etching composition that includes: (1) at least one quaternary ammonium hydroxide or salt thereof in an amount from about 1% to about 15% by weight of the composition; (2) at least one oxidizing agent in an amount from about 0.1% to about 5% by weight of the composition; (3) at least one acid different from the at least one oxidizing agent in an amount from about 0.01% to about 0.5% by weight of the composition; and (4) water.

[0010] In another aspect, the disclosure features an etching composition that includes: (1) at least one quaternary ammonium hydroxide or salt thereof; (2) at least one oxidizing agent; (3) at least one acid different from the at least one oxidizing agent; and (4) water.

[0011] In another aspect, the disclosure features an etching composition that includes: (1) at least one quaternary ammonium hydroxide or salt thereof; (2) at least one oxidizing agent; (3) at least one acid, including sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid; and (4) water.

[0012] In another aspect, the disclosure features an etching composition that includes: (1) tetramethylammonium hydroxide, (2) periodic acid, (3) at least one acid including boric acid, phosphoric acid, sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid, and (4) water.

[0013] In another aspect, the disclosure features a method that includes contacting a semiconductor substrate containing a Si film (e.g., a Si-containing feature) with an etching composition described herein to substantially remove the Si film.

[0014] In yet another aspect, the disclosure features an article formed by the above method that is a semiconductor device (eg, an integrated circuit). DETAILED DESCRIPTION OF THE INVENTION

[0015] As defined herein, unless otherwise specified, all expressed percentages are understood to be weight percents based on the total weight of the composition. Ambient temperature is defined to be about 16 degrees Celsius to about 27 degrees Celsius (°C) unless otherwise specified. As used herein, the terms "layer" and "film" are used interchangeably.

[0016] In general, the present disclosure features an etching composition (e.g., an etching composition for selectively removing Si) that includes (e.g., comprises or consists of) at least one quaternary ammonium hydroxide or salt thereof, at least one oxidizing agent, at least one acid different from the at least one oxidizing agent, and water. In some embodiments, the etching composition contains only these four components. In some embodiments, the Si to be removed is amorphous silicon or polysilicon (poly-Si), such as doped poly-Si (e.g., n-type poly-Si or p-type poly-Si). The doped poly-Si can include a suitable dopant, such as phosphorus, boron, or other suitable element.

[0017] In some embodiments, the etching compositions of the present disclosure may include at least one (e.g., two, three, or four) quaternary ammonium hydroxide or salt thereof. The quaternary ammonium hydroxide or salt thereof described herein may be a tetraalkylammonium hydroxide or salt thereof (e.g., a fluoride salt, a chloride salt, or a bromide salt). In some embodiments, each alkyl group in the tetraalkylammonium hydroxide is independently a C1-C substituted alkyl group optionally substituted with OH or aryl (e.g., phenyl). 18Examples of suitable tetraalkylammonium hydroxides or salts thereof include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide (BTMAH), methyltriethylammonium hydroxide, ethyltrimethylammonium hydroxide (ETMAH), dimethyldiethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, tetraethanolammonium hydroxide, benzyltriethylammonium hydroxide, benzyltributylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and salts thereof.

[0018] In some embodiments, the at least one quaternary ammonium hydroxide or salt thereof is present in an amount of about 1 wt. % or more (e.g., about 2 wt. % or more, about 3 wt. % or more, about 4 wt. % or more, about 5 wt. % or more, about 6 wt. % or more, about 7 wt. % or more, or about 8 wt. % or more) to about 15 wt. % or less (e.g., about 14 wt. % or less, about 12 wt. % or less, about 10 wt. % or less, about 8 wt. % or less, about 7 wt. % or less, about 6 wt. % or less, or about 5 wt. % or less) of the etching composition of the present disclosure. Without being bound by theory, it is believed that the quaternary ammonium hydroxide or salt thereof can facilitate and enhance the removal of Si on a semiconductor substrate during an etching process.

[0019] The etching compositions of the present disclosure can 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.

[0020] In some embodiments, the at least one oxidizing agent may be present in an amount of about 0.1 wt % or more (e.g., about 0.2 wt % or more, about 0.3 wt % or more, about 0.4 wt % or more, about 0.5 wt % or more, about 0.6 wt % or more, about 0.7 wt % or more, about 0.8 wt % or more, about 0.9 wt % or more, or about 1 wt % or more) to about 5 wt % or less (e.g., about 4.5 wt % or less, about 4 wt % or less, about 3.5 wt % or less, about 3 wt % or less, about 2.5 wt % or less, about 2 wt % or less, about 1.5 wt % or less, about 1 wt % or less, about 0.9 wt % or less, about 0.8 wt % or less, about 0.7 wt % or less, about 0.6 wt % or less, or about 0.5 wt % or less) of the etching composition of the present disclosure. Without being bound by theory, it is believed that the oxidizing agent can facilitate and enhance the removal of Si (e.g., poly-Si or doped poly-Si) on semiconductor substrates (e.g., in high aspect vials).

[0021] In general, etching compositions of the present disclosure can include at least one (e.g., two, three, or four) acid(s) different from at least one oxidizing agent described herein. In some embodiments, the acid can be an inorganic acid (e.g., sulfuric acid) or an organic acid. Examples of suitable inorganic acids include boric acid, phosphoric acid, and sulfuric acid. Examples of suitable organic acids include phosphonic acids (e.g., methylphosphonic acid or phenylphosphonic acid), carboxylic acids (e.g., C2-C6 carboxylic acids such as propionic acid), and organic acids containing heteroaromatic rings (e.g., picolinic acid).

[0022] In some embodiments, the at least one acid may be present in an amount of about 0.01 wt.% or more (e.g., about 0.02 wt.% or more, about 0.04 wt.% or more, about 0.05 wt.% or more, about 0.06 wt.% or more, about 0.08 wt.% or more, about 0.1 wt.% or more, about 0.15 wt.% or more, about 0.2 wt.% or more, about 0.25 wt.% or more, or about 0.3 wt.% or more) to about 0.5 wt.% or less (e.g., about 0.45 wt.% or less, about 0.4 wt.% or less, about 0.35 wt.% or less, about 0.3 wt.% or less, about 0.25 wt.% or less, about 0.2 wt.% or less, about 0.15 wt.% or less, or about 0.1 wt.% or less) of the etching composition of the present disclosure. Without being bound by theory, it is believed that the acid can further improve the etch selectivity between poly-Si and surrounding dielectric materials such as SiOx and SiN.

[0023] In general, etching compositions of the present disclosure can include water as a solvent. In some embodiments, the water can be deionized water or ultrapure water, can be water free of organic contaminants, and / or can have a minimum resistivity of about 4 to about 17 megaohms, or at least about 17 megaohms. In some embodiments, the water is present in an amount of about 80% by weight or more (e.g., about 82% by weight or more, about 84% by weight or more, about 85% by weight or more, about 86% by weight or more, about 88% by weight or more, about 90% by weight or more, about 91% by weight or more, or about 92% by weight or more) to about 99% by weight or less (e.g., about 98% by weight or less, about 97% by weight or less, about 96% by weight or less, about 95% by weight or less, about 94% by weight or less, about 93% by weight or less, about 92% by weight or less, about 91% by weight or less, about 90% by weight or less, about 85% by weight or less, or about 80% by weight or less) of the etching composition. Without being bound by theory, it is believed that if the amount of water exceeds 99% by weight of the composition, the Si etch rate will be adversely affected, resulting in reduced Si removal during the etching process. On the other hand, without being bound by theory, it is believed that the etching compositions of the present disclosure should contain a certain level of water (e.g., at least about 80% by weight) to avoid reduced etching performance.

[0024] In some embodiments, the etching compositions of the present disclosure may optionally include at least one (e.g., two, three, or four) organic solvent. In some embodiments, the organic solvent may be a water-soluble organic solvent. As defined herein, a "water-soluble" substance (e.g., a water-soluble organic solvent) means a substance that has a solubility of at least 1% by weight in water at 25°C. In some embodiments, the organic solvent may be selected from the group consisting of water-soluble alcohols (e.g., glycols such as alkanediols or 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.

[0025] In some embodiments, the at least one organic solvent may be present in an amount of about 5% by weight or more (e.g., about 10% by weight or more, about 15% by weight or more, about 20% by weight or more, about 25% by weight or more, about 30% by weight or more, about 35% by weight or more, or about 40% by weight or more) to about 75% by weight or less (e.g., about 70% by weight or less, about 65% by weight or less, about 60% by weight or less, about 55% by weight or less, about 50% by weight or less, about 45% by weight or less, or about 40% by weight or less) of the etching composition. In some embodiments, the etching compositions of the present disclosure may be substantially free of organic solvents.

[0026] In some embodiments, the etching compositions of the present disclosure may have a pH of about 13 or greater (e.g., about 13.1 or greater, about 13.2 or greater, about 13.3 or greater, about 13.4 or greater, or about 13.5 or greater) and / or about 14 or less (e.g., about 13.9 or less, about 13.8 or less, about 13.7 or less, about 13.6 or less, or about 13.5 or less). Without being bound by theory, it is believed that etching compositions having a pH less than 13 do not have sufficient Si removal rates and / or sufficient bath loading capacity.

[0027] In some embodiments, the cleaning compositions of the present disclosure may optionally include at least one (e.g., two, three, or four) pH adjusters (e.g., acids or bases) to adjust the pH to about 13 to about 14. The amount of pH adjuster required, if present, may vary as the concentrations of other ingredients (e.g., quaternary ammonium hydroxides and acids) are altered in different formulations. In some embodiments, the pH adjuster may be present in an amount of about 0.1 wt.% or more (e.g., about 0.2 wt.% or more, about 0.4 wt.% or more, about 0.5 wt.% or more, about 0.6 wt.% or more, about 0.8 wt.% or more, about 1 wt.% or more, about 1.2 wt.% or more, about 1.4 wt.% or more, or about 1.5 wt.% or more) and / or about 3 wt.% or less (e.g., about 2.8 wt.% or less, about 2.6 wt.% or less, about 2.5 wt.% or less, about 2.4 wt.% or less, about 2.2 wt.% or less, about 2 wt.% or less, or about 1.8 wt.% or less) of the etching composition. In some embodiments, the etching compositions of the present disclosure may be substantially free of pH adjusters.

[0028] In some embodiments, the pH adjuster is completely metal ion-free (except for trace amounts of metal ion impurities). Suitable metal-ion-free pH adjusters include acids and bases. Suitable acids that can be used as pH adjusters 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, monocarboxylic alpha-hydroxy acids and beta-hydroxy acids, bicarboxylic acid alpha-hydroxy acids or beta-hydroxy acids, or tricarboxylic acid alpha-hydroxy acids and beta-hydroxy 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.

[0029] Suitable bases that can be used as pH adjusters 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.

[0030] In some embodiments, the etching compositions of the present disclosure may optionally contain additives such as pH adjusters, corrosion inhibitors, surfactants, additional organic solvents, biocides, and antifoaming agents. Some examples of suitable additives include alcohols (e.g., polyvinyl alcohol and sugar alcohols). Examples of suitable antifoaming agents include polysiloxane antifoams (e.g., polydimethylsiloxane), polyethylene glycol methyl ether polymers, ethylene oxide / propylene oxide copolymers, and glycidyl ether-capped acetylene diol ethoxylates (such as those described in U.S. Pat. No. 6,717,019, incorporated herein by reference). Examples of suitable surfactants may be cationic, anionic, nonionic, and amphiphilic surfactants.

[0031] In general, the etching compositions of the present disclosure can have a relatively high Si / dielectric material (e.g., SiN, SiOx, or SiCO) removal rate selectivity (i.e., a high ratio of Si removal rate to dielectric material removal rate). In some embodiments, the etching compositions can have a Si / dielectric material removal rate selectivity of about 10 or greater (e.g., about 20 or greater, about 40 or greater, about 50 or greater, about 60 or greater, about 80 or greater, about 100 or greater, about 150 or greater, about 200 or greater, about 250 or greater, about 300 or greater, about 350 or greater, about 400 or greater, about 450 or greater, about 500 or greater, or about 1000 or greater) and / or about 5000 or less (e.g., about 4000 or less, about 3000 or less, about 2000 or less, or about 1000 or less).

[0032] In some embodiments, the etching compositions of the present disclosure may be substantially free of one or more additive components, or any combination of two or more. Such ingredients include organic solvents, polymers (e.g., nonionic, cationic, or anionic polymers), oxygen scavengers, quaternary ammonium compounds (e.g., salts or hydroxides), alkali bases (such as NaOH, KOH, LiOH, Mg(OH)2, and Ca(OH)2), surfactants (e.g., cationic, anionic, or nonionic surfactants), antifoaming agents, fluorine-containing compounds (e.g., fluoride compounds or fluorinated compounds (e.g., fluorinated polymers / fluorinated surfactants)), silicon-containing compounds such as silanes (e.g., alkoxysilanes), nitrogen-containing compounds (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 surfactants), and the like. The additives are selected from the group consisting of ionic abrasives, surface-modified abrasives, negatively / positively charged abrasives, or ceramic-abrasive composites, plasticizers, oxidizers (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 (e.g., cyclic compounds containing at least two rings such as azoles (e.g., diazoles, triazoles, or tetrazoles), triazines, and substituted or unsubstituted naphthalenes or substituted or unsubstituted biphenyl ethers), chelating agents, buffers, acids such as organic acids (e.g., carboxylic acids such as hydroxycarboxylic acids, polycarboxylic acids, and sulfonic acids) 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 salts other than quaternary ammonium salts. As used herein, an etching composition that is "substantially free" of a component means that the component is not intentionally added to the etching composition.In some embodiments, the etching compositions described herein can have about 1000 ppm or less (e.g., about 500 ppm or less, about 250 ppm or less, about 100 ppm or less, about 50 ppm or less, about 10 ppm or less, or about 1 ppm or less) of one or more of the above components from which the etching composition is substantially free. In some embodiments, the etching compositions described herein can be completely free of one or more of the above components.

[0033] In some embodiments, the etching compositions of the present disclosure may be substantially free of activators, organic solvents (such as those described herein), or phosphoric acid. As used herein, the term "activator" refers to a material or compound that increases the TiN etch rate. For example, the activator described herein may include a material selected from the group consisting of acetic acid, ammonium acetate, sodium acetate, potassium acetate, tetramethylammonium acetate and other tetraalkylammonium acetates, phosphonium acetate, ammonium butyrate, ammonium trifluoroacetate, amino acids, phosphoric acid, diammonium monohydrogen phosphate, ammonium dihydrogen phosphate, bis(tetramethylammonium) monohydrogen phosphate, disodium monohydrogen phosphate, sodium dihydrogen phosphate, dipotassium monohydrogen phosphate, potassium dihydrogen phosphate, ditetraalkylammonium monohydrogen phosphate, ditetraalkylammonium dihydrogen phosphate, diphosphonium monohydrogen phosphate, phosphonium dihydrogen phosphate, ammonium phosphonate, tetraalkylammonium phosphonate, sodium phosphonate, potassium phosphonate, phosphonium phosphonate, and combinations thereof.

[0034] The etching compositions of the present disclosure may be prepared by simply mixing the components together, or may be prepared by blending two or more compositions provided in a kit, each containing particular components of the etching compositions described herein.

[0035] In some embodiments, the present disclosure features a method for etching a semiconductor substrate that includes a Si film (e.g., in a Si-containing feature). The method can include contacting the semiconductor substrate containing a Si film (e.g., a poly-Si film) with an etching composition of the present disclosure to substantially remove the Si film. In some embodiments, the semiconductor substrate can include a pattern or feature on a surface, and the Si film is part of the pattern or feature. In some embodiments, the method can further include rinsing the semiconductor substrate with a rinsing solvent after the contacting step and / or drying the semiconductor substrate after the rinsing step.

[0036] In some embodiments, the method does not substantially remove dielectric material (e.g., SiN, SiOx, or SiCO) present in the semiconductor substrate, for example, the method does not remove more than about 5% by weight (e.g., not more than about 3% by weight, or not more than about 1% by weight) of metal conductor or dielectric material present in the semiconductor substrate.

[0037] In some embodiments, the etching method comprises: (A) providing a semiconductor substrate containing a Si film (e.g., a poly-Si film in a pattern or feature); (B) contacting the semiconductor substrate with an etching composition described herein; (C) rinsing the semiconductor substrate with one or more suitable rinsing solvents; and (D) optionally drying the semiconductor substrate (e.g., by any suitable means that removes the rinse solvent and does not compromise the integrity of the semiconductor substrate); Includes.

[0038] Semiconductor substrates etched in this manner may contain organic and organometallic residues, as well as various metal oxides, some or all of which may also be removed during the etching process.

[0039] The semiconductor substrates (e.g., wafers) described herein are typically constructed from silicon, silicon germanium, Group III-Group V compounds such as GaAs, or any combination thereof. The semiconductor substrate may further contain exposed integrated circuit structures, such as interconnect features (e.g., metal lines and dielectric materials). Metals and metal alloys used in 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 substrate may also contain layers of interlayer dielectrics, polysilicon, silicon oxide, silicon nitride, silicon germanium, silicon carbide, titanium oxide, and carbon-doped silicon oxide.

[0040] The semiconductor substrate can be contacted with the etching composition in any suitable manner, such as by placing the etching composition in a bath and dipping and / or submerging the semiconductor substrate in the etching composition, by spraying the etching composition onto the semiconductor substrate, by flowing the etching composition onto the semiconductor substrate, or any combination thereof.

[0041] Etching compositions of the present disclosure can be effectively used at temperatures up to about 85°C (e.g., about 50°C to about 85°C, about 60°C to about 80°C, or about 65°C to about 75°C). Because the Si etch rate increases with temperature within this range, processes at higher temperatures can be performed in shorter times. Conversely, lower etching temperatures typically require longer etching times.

[0042] Etching times can vary widely depending on the particular etching method, thickness, and temperature used. For etching by a dipping batch process, a suitable time range is, for example, about 10 minutes or less (e.g., about 1 minute to about 7 minutes, about 1 minute to about 5 minutes, or about 2 minutes to about 4 minutes). For single-wafer processes, etching times can range from about 30 seconds to about 60 minutes (e.g., about 10 minutes to about 60 minutes, about 20 minutes to about 60 minutes, or about 30 minutes to about 60 minutes).

[0043] To further enhance the etching ability of the etching composition of the present disclosure, mechanical agitation means may be used. Examples of suitable agitation means include circulation of the etching composition over the substrate, flow or spraying of 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 may be at any angle. A horizontal or vertical orientation is preferred.

[0044] Following etching, the semiconductor substrate may be rinsed with an appropriate rinse solvent for about 5 seconds to about 5 minutes, with or without agitation. Multiple rinse steps using different rinse solvents may be used. Examples of suitable rinse solvents include, but are not limited to, deionized (DI) water, methanol, ethanol, isopropyl alcohol, N-methylpyrrolidinone, γ-butyrolactone, dimethyl sulfoxide, ethyl lactate, and propylene glycol monomethyl ether acetate. Alternatively or additionally, an aqueous rinse solution with a pH >8 (such as a dilute aqueous ammonium hydroxide solution) may be used. The rinse solvent may be applied using a method similar to that used to apply the etching compositions described herein. The etching composition may be removed from the semiconductor substrate before the rinsing step begins, or may still be in contact with the semiconductor substrate at the start of the rinsing step. In some embodiments, the temperature used in the rinsing step is between 16°C and 27°C.

[0045] Optionally, the semiconductor substrate is dried after the rinsing step. Any suitable drying means known in the art may be used. Examples of suitable drying means include spin drying, flowing a drying gas over the semiconductor substrate, or heating the semiconductor substrate using a heating means such as a hot plate or infrared lamp, Maragoni drying, Rotagoni drying, IPA drying, and any combination thereof. Drying times vary depending on the specific method used, but are typically on the order of 30 seconds to several minutes.

[0046] In some embodiments, the etching methods described herein further include forming a semiconductor device (eg, an integrated circuit device such as a semiconductor chip) from the semiconductor substrate obtained by the method.

[0047] Although the invention has been described in detail with reference to specific embodiments thereof, it will be understood that modifications and variations are within the spirit and scope of what is described in the specification and claims. [Example]

[0048] General Procedure 1 Formulation Blend Samples of the etching composition were prepared by adding the remaining ingredients of the formulation to the calculated amount of solvent with stirring.

[0049] General Procedure 2 Materials and Methods Blanket film etch rate measurements for films were performed using commercially available 300 mm diameter unpatterned wafers that were diced into 0.5" x 1.0" test coupons for evaluation. The main blanket film materials tested included: 1) approximately 3000 Å thick polysilicon (poly-Si) films deposited on silicon substrates; 2) approximately 140 Å thick SiN films deposited on silicon substrates; 3) approximately 300 Å thick SiN films deposited on silicon substrates; and 4) approximately 1200 Å thick SiOx films deposited on silicon substrates.

[0050] Blanket film test coupons were measured for pre- and post-treatment thickness to determine blanket film etch rates. For poly-Si, SiN, and SiOx blanket films, film thickness was measured pre- and post-treatment by ellipsometry using a Woollam VASE.

[0051] General Procedure 3 Etching evaluation by beaker test All blanket film etching tests were conducted in a 150 ml PFA bottle containing 100 g of sample solution with continuous stirring at 250 rpm. The PFA bottle was immersed in a 600 ml glass beaker filled with water, which acted as a water bath. The beaker was placed on a hotplate stirrer set to the desired temperature. All blanket test coupons, with the blanket film exposed to the sample solution on one side, were diced with a diamond scribe into 0.5" x 1.0" square test coupons for beaker-scale testing. Each test coupon was held in place using a single 4" long locking plastic tweezers clip. The test coupon, held at one end by the locking tweezers clip, was suspended in a 150 ml PFA bottle and immersed in 100 g of test solution with the solution continuously stirred at 250 rpm at 70 °C or 75 °C. The test coupons were held stationary in the stirred solution until the treatment time (0.5 or 60 minutes) had elapsed.

[0052] After the test solution treatment time, the sample coupons were immediately removed from the 150 ml PFA bottle and rinsed. Specifically, the coupons were immersed in a 300 ml volume of ultra-high-purity deionized (DI) water for 15 seconds with gentle agitation, then immersed in 300 ml of isopropyl alcohol (IPA) for 15 seconds with gentle agitation, and finally immersed in 300 ml of IPA for 15 seconds with gentle agitation. After the final IPA rinse, all test coupons were subjected to a blowdown with filtered nitrogen gas using a handheld nitrogen blower to forcefully remove all traces of IPA and obtain the final dry sample for test measurements.

[0053] Example 1 Formulation Examples 1-16 (FE-1-FE-16) and Comparative Formulation Examples 1-3 (CFE-1-CFE-3) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and their test results are summarized in Tables 1 and 2. In Table 1, the poly-Si etch rate was measured after immersing a test coupon in the formulation for 0.5 minutes at 75°C, and the SiN and SiOx etch rates were measured after immersing a test coupon in the formulation for 60 minutes at 75°C. [Table 1] SA = Sulfuric acid, PA = Phosphoric acid, ER = Etch rate

[0054] In Table 2, the poly-Si etch rates were measured after immersing the test coupons in the formulations for 0.5 minutes at 70° C., and the SiN and SiOx etch rates were measured after immersing the test coupons in the formulations for 60 minutes at 70° C. Also, the SiN etch rates for FE-5 to FE-10 were obtained from a SiN film (Film A) having a thickness of approximately 140 Å, and the SiN etch rates for FE-11 to FE-16 were obtained from a SiN film (Film B) having a thickness of approximately 300 Å. [Table 2] SA = sulfuric acid PA = phosphoric acid BA = boric acid PPA = phenylphosphonic acid, PRA = propionic acid, PLA = picolinic acid MPA = methylphosphonic acid ER = etch rate

[0055] As shown in Tables 1 and 2, FE-1 to FE-16 (all of which contained an acid different from the oxidizer) showed improved etch rate selectivity for Poly-Si / SiN and / or Poly-SiN / SiOx compared to CFE-1 to CFE-13 (which did not contain an acid different from the oxidizer).

Claims

1. at least one quaternary ammonium hydroxide or salt thereof; at least one oxidizing agent; at least one acid different from the at least one oxidizing agent; and water, and being substantially free of activators and organic solvents.

2. at least one quaternary ammonium hydroxide or salt thereof in an amount of about 1% to about 15% by weight of the composition; at least one oxidizing agent in an amount of about 0.1% to about 5% by weight of the composition; at least one acid different from the at least one oxidizing agent in an amount of about 0.01% to about 0.5% by weight of the composition; and water, 1. An etching composition comprising:

3. at least one quaternary ammonium hydroxide or salt thereof; at least one oxidizing agent; at least one acid different from the at least one oxidizing agent; and water, An etching composition comprising:

4. at least one quaternary ammonium hydroxide or salt thereof; at least one oxidizing agent; at least one acid comprising sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid; and water, 1. An etching composition comprising:

5. The composition of any one of claims 1 to 4, wherein the at least one quaternary ammonium hydroxide or salt thereof comprises tetramethylammonium hydroxide, tetraethylammonium hydroxide, or tetrabutylammonium hydroxide.

6. 6. The composition of claim 1, wherein the at least one quaternary ammonium hydroxide or salt thereof is present in an amount of from about 1% to about 15% by weight of the composition.

7. The composition of any one of claims 1 to 6, wherein the at least one oxidizing agent comprises periodic acid.

8. The composition of any one of claims 1 and 3 to 7, wherein the at least one oxidizing agent is present in an amount of from about 0.1% to about 5% by weight of the composition.

9. The composition of any one of claims 1 to 3 and claims 5 to 8, wherein the at least one acid comprises boric acid, phosphoric acid, sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid.

10. The composition of any one of claims 1 and 3 to 9, wherein the at least one acid is present in an amount of from about 0.01% to about 0.5% by weight of the composition.

11. The composition of any one of claims 1 to 10, wherein the water is present in an amount of from about 80% to about 99% by weight of the composition.

12. The composition of any one of claims 1 to 11, having a pH of about 13 to about 14.

13. tetramethylammonium hydroxide, periodic acid, at least one acid comprising boric acid, phosphoric acid, sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid; and water, 1. An etching composition comprising:

14. 14. The composition of claim 13, wherein the tetramethylammonium hydroxide is in an amount of about 1% to about 15% by weight of the composition.

15. 15. The composition of claim 13 or claim 14, wherein the periodic acid is present in an amount of from about 0.1% to about 5% by weight of the composition.

16. The composition of any one of claims 13 to 15, wherein the at least one acid is present in an amount of from about 0.01% to about 0.5% by weight of the composition.

17. The composition of any one of claims 13 to 16, wherein the water is present in an amount of from about 80% to about 99% by weight of the composition.

18. The composition of any one of claims 13 to 17, having a pH of about 13 to about 14.

19. 19. A method comprising contacting a semiconductor substrate containing a Si film with the composition of any one of claims 1 to 18 to substantially remove the Si film.

20. 20. The method of claim 19, wherein substantially no silicon oxide or silicon nitride is removed.

21. 21. An article formed by the method of claim 19 or claim 20, which is a semiconductor device.

22. 22. The article of claim 21, wherein the semiconductor device is an integrated circuit.

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