Etching composition

Abstract

The present disclosure is directed to etching compositions suitable, for example, for selectively removing silicon from a semiconductor substrate as an intermediate step in a multi-step semiconductor manufacturing process.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 399,077, filed on August 18, 2022, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to etching compositions and methods of 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, insulator materials (e.g., low-k dielectric materials). Background Art

[0004] The semiconductor industry is rapidly reducing the size and increasing the density of electronic circuits and electronic components in microelectronic devices, silicon chips, memory chips, liquid crystal displays, micro electromechanical systems (MEMS), printed wiring boards, and the like. The integrated circuits therein are layered or stacked with insulating layers, and the thickness of the insulating layers is decreasing between each circuit layer. As feature sizes shrink, patterns become smaller and device performance parameters become tighter and more robust. As a result, various problems caused by smaller feature sizes that were previously tolerable are no longer tolerable or are more problematic.

[0005] In the production of advanced integrated circuits, high-k and low-k insulators and hybrid barrier layer materials have been employed to minimize problems associated with higher density and to optimize performance.

[0006] Silicon (Si) can be used in the manufacture of semiconductor devices, liquid crystal displays, micro-electromechanical systems (MEMS), printed wiring boards, and the like. Silicon often needs to be removed during etching processes in the presence of other exposed materials in the semiconductor substrate. Summary of the invention

[0007] In the construction of semiconductor devices, it is often necessary to etch silicon (Si). In various types of Si applications and device environments, other layers are in contact with this material or are exposed while etching this material. 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 often required for device yield and long life.

[0008] The present disclosure relates to compositions and methods 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 oxides, or SiCO) present in semiconductor devices. More specifically, the present disclosure relates to compositions and methods for selectively etching Si relative to SiOx and / or SiN.

[0009] In one aspect, the disclosure features an etching composition comprising (1) at least one quaternary ammonium hydroxide or a salt thereof; (2) at least one oxidizing agent; (3) at least one acid different from the at least one oxidizing agent; and (4) water, wherein the composition is substantially free of an activator and an organic solvent.

[0010] In another aspect, the disclosure features an etching composition that includes (1) at least one quaternary ammonium hydroxide or a salt thereof in an amount of about 1 wt % to about 15 wt % of the composition; (2) at least one oxidizing agent in an amount of about 0.1 wt % to about 5 wt % of the composition; (3) at least one acid different from the at least one oxidizing agent, the at least one acid in an amount of about 0.01 wt % to about 0.5 wt % of the composition; and (4) water.

[0011] In another aspect, the disclosure features an etching composition consisting of: (1) at least one quaternary ammonium hydroxide or a salt thereof; (2) at least one oxidizing agent; (3) at least one acid different from the at least one oxidizing agent; and (4) water.

[0012] In another aspect, the disclosure features an etching composition comprising: (1) at least one quaternary ammonium hydroxide or a salt thereof; (2) at least one oxidizing agent; (3) at least one acid comprising sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid; and (4) water.

[0013] In another aspect, the disclosure features an etching composition that includes: (1) tetramethylammonium hydroxide; (2) periodic acid; (3) at least one acid comprising boric acid, phosphoric acid, sulfuric acid, methylphosphonic acid, phenylphosphonic acid, propionic acid, or picolinic acid; or (4) water.

[0014] In another aspect, the disclosure features a method that includes contacting a semiconductor substrate containing a Si film (eg, in a Si-containing feature) with an etching composition described herein to substantially remove the Si film.

[0015] In yet another aspect, the disclosure features an article formed by the method described above, where the article is a semiconductor device (eg, an integrated circuit). DETAILED DESCRIPTION

[0016] As defined herein, all percentages expressed are understood to be weight percentages relative to the total weight of the composition unless otherwise indicated. Ambient temperature is defined as being between about 16 and about 27 degrees Celsius (° C.) unless otherwise indicated. As used herein, the terms “layer” and “film” are used interchangeably.

[0017] In general, the present disclosure features an etching composition (e.g., an etching composition for selectively removing Si) comprising (e.g., including or consisting of) at least one quaternary ammonium hydroxide or a 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 types of components. In some embodiments, the Si to be removed is amorphous silicon or polycrystalline silicon (poly-Si), such as doped poly-Si (e.g., n-type poly-Si or p-type poly-Si). The doped poly-Si may include a suitable dopant, such as phosphorus, boron, or other suitable elements.

[0018] In some embodiments, the etching composition 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, chloride, or bromide salt). In some embodiments, each alkyl group in the tetraalkylammonium hydroxide is independently a C1-C ... 18 Examples 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.

[0019] In some embodiments, the amount of at least one quaternary ammonium hydroxide or a salt thereof is at least about 1 wt % (e.g., at least about 2 wt %, at least about 3 wt %, at least about 4 wt %, at least about 5 wt %, at least about 6 wt %, at least about 7 wt %, or at least about 8 wt %) to at most about 15 wt % (e.g., at most about 14 wt %, at most about 12 wt %, at most about 10 wt %, at most about 8 wt %, at most about 7 wt %, at most about 6 wt %, or at most about 5 wt %) of the etching composition of the present disclosure. Without wishing to be bound by theory, it is believed that the quaternary ammonium hydroxide or a salt thereof can facilitate and enhance the removal of Si on the semiconductor substrate during the etching process.

[0020] The etching composition of the present disclosure may include at least one (eg, two, three, or four) oxidizing agents. Examples of suitable oxidizing agents include periodic acid, perchloric acid, and hydrogen peroxide.

[0021] In some embodiments, at least one oxidizing agent may comprise 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 the present disclosure. Without wishing to be bound by theory, it is believed that the oxidizing agent may aid and enhance the removal of Si (e.g., polycrystalline Si or doped polycrystalline Si) on a semiconductor substrate (e.g., in a high aspect ratio via).

[0022] In general, the etching compositions of the present disclosure may include at least one (e.g., two, three, or four) acid different from at least one oxidizing agent described herein. In some embodiments, the acid may 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).

[0023] In some embodiments, at least one acid may be at least about 0.01 wt% (e.g., at least about 0.02 wt%, at least about 0.04 wt%, at least about 0.05 wt%, at least about 0.06 wt%, at least about 0.08 wt%, at least about 0.1 wt%, at least about 0.15 wt%, at least about 0.2 wt%, at least about 0.25 wt%, or at least about 0.3 wt%) to at most about 0.5 wt% (e.g., at most about 0.45 wt%, at most about 0.4 wt%, at most about 0.35 wt%, at most about 0.3 wt%, at most about 0.25 wt%, at most about 0.2 wt%, at most about 0.15 wt%, or at most about 0.1 wt%) of the etching composition of the present disclosure. Without wishing to be bound by theory, it is believed that the acid may further improve the etch selectivity between poly-Si and surrounding dielectric materials such as SiOx and SiN.

[0024] In general, the etching composition of the present disclosure may include water as a solvent. In some embodiments, the water may be deionized and ultrapure, free of organic contaminants, and / or have a minimum resistivity of about 4 to about 17 megohms or at least about 17 megohms. In some embodiments, the amount of water is at least about 80wt% (e.g., at least about 82wt%, at least about 84wt%, at least about 85wt%, at least about 86wt%, at least about 88wt%, at least about 90wt%, at least about 91wt%, or at least about 92wt%) of the etching composition to a maximum of about 99wt% (e.g., at most about 98wt%, at most about 97wt%, at most about 96wt%, at most about 95wt%, at most about 94wt%, at most about 93wt%, at most about 92wt%, at most about 91wt%, at most about 90wt%, at most about 85wt%, or at most about 80wt%). Without wishing to be bound by theory, it is believed that if the amount of water exceeds 99 wt % of the composition, it will adversely affect the Si etching rate and reduce its removal during the etching process. On the other hand, without wishing to be bound by theory, it is believed that the etching compositions of the present disclosure should include a certain level of water (e.g., at least about 80 wt %) to avoid reduced etching performance.

[0025] In some embodiments, the etching composition of the present disclosure may optionally include at least one (e.g., two, three, or four) organic solvents. 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) refers to a substance having 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., 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-propylene glycol, ethylene glycol butyl ether, 3-methoxy-3-methyl-1-butanol, acetone, cyclohexanone, ethyl acetate, and propylene glycol monoethyl ether acetate.

[0026] In some embodiments, at least one organic solvent may be at least about 5 wt % (e.g., at least about 10 wt %, at least about 15 wt %, at least about 20 wt %, at least about 25 wt %, at least about 30 wt %, at least about 35 wt %, or at least about 40 wt %) to at most about 75 wt % (e.g., at most about 70 wt %, at most about 65 wt %, at most about 60 wt %, at most about 55 wt %, at most about 50 wt %, at most about 45 wt %, or at most about 40 wt %) of the etching composition. In some embodiments, the etching composition of the present disclosure may be substantially free of an organic solvent.

[0027] In some embodiments, the etching compositions of the present disclosure may have a pH of at least about 13 (e.g., at least about 13.1, at least about 13.2, at least about 13.3, at least about 13.4, or at least about 13.5) and / or at most about 14 (e.g., at most about 13.9, at most about 13.8, at most about 13.7, at most about 13.6, or at most about 13.5). Without wishing to be bound by theory, it is believed that etching compositions having a pH below 13 will not have sufficient Si removal rates and / or sufficient bath loading capacity.

[0028] In some embodiments, the cleaning composition of the present disclosure may optionally include at least one (e.g., two, three, or four) pH adjusters (e.g., acids or bases) to control the pH to about 13 to about 14. The amount of the required pH adjuster (if present) may vary as the concentrations of other components (e.g., quaternary ammonium hydroxide and acid) vary in different formulations. In some embodiments, the pH adjuster may 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 up to about 3 wt% (e.g., up to about 2.8 wt%, up to about 2.6 wt%, up to about 2.5 wt%, up to about 2.4 wt%, up to about 2.2 wt%, up to about 2 wt%, or up to about 1.8 wt%) of the etching composition. In some embodiments, the etching composition of the present disclosure may be substantially free of a pH adjuster.

[0029] In some embodiments, the pH regulator does not contain any metal ions (except trace metal ion impurities). Suitable metal ion-free pH regulators include acids and bases. Suitable acids that can be used as pH regulators include organic acids (e.g., carboxylic acids) and inorganic acids. Exemplary carboxylic acids include, but are not limited to, monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, α-hydroxy acids and β-hydroxy acids of monocarboxylic acids, α-hydroxy acids or β-hydroxy acids of dicarboxylic acids, or α-hydroxy acids and β-hydroxy acids 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.

[0030] 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.

[0031] In some embodiments, the etching compositions of the present disclosure may contain additives such as pH adjusters, corrosion inhibitors, surfactants, additional organic solvents, biocides, and defoamers as optional components. Examples of some suitable additives include alcohols (e.g., polyvinyl alcohol and sugar alcohols). Examples of suitable defoamers include polysiloxane defoamers (e.g., polydimethylsiloxane), polyethylene glycol methyl ether polymers, ethylene oxide / propylene oxide copolymers, and glycidyl ether-terminated acetylenic glycol ethoxylates (such as those described in U.S. Pat. No. 6,717,019, which is incorporated herein by reference). Examples of suitable surfactants may be cationic, anionic, nonionic, and amphoteric surfactants.

[0032] In general, the etching compositions of the present disclosure may have a relatively high Si / dielectric material (e.g., SiN, SiOx, or SiCO) removal rate selectivity (i.e., a high Si removal rate compared to a dielectric material removal rate). In some embodiments, the etching compositions may have a Si / dielectric material 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).

[0033] In some embodiments, the etching compositions of the present disclosure may be substantially free of one or more of the additive components, if more than one, any combination). Such components are selected from the group consisting of an organic solvent, a polymer (e.g., a nonionic, cationic, or anionic polymer), a deoxidizer, a quaternary ammonium compound (e.g., a salt or hydroxide), an alkaline base (such as NaOH, KOH, LiOH, Mg(OH)2, and Ca(OH)2), a surfactant (e.g., a cationic, anionic, or nonionic surfactant), a defoaming agent, a fluorine-containing compound (e.g., a fluoride compound or a fluorinated compound (such as a fluorinated polymer / surfactant)), a silicon-containing compound (such as a silane (e.g., an alkoxysilane)), a nitrogen-containing compound (e.g., an amino acid, an amine, an imine (e.g., an amidine, such as 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN)), an amide or an acyl group. imines), abrasives (e.g., cerium oxide abrasives, non-ionic abrasives, surface modified abrasives, negatively / positively charged abrasives, or ceramic abrasive composites), plasticizers, oxidants (e.g., peroxides such as hydrogen peroxide, and periodic acid), corrosion inhibitors (e.g., azoles or non-azole corrosion inhibitors), electrolytes (e.g., polyelectrolytes), silicates, cyclic compounds (e.g., azoles (e.g., diazoles, triazoles, or tetrazoles), triazines, and cyclic compounds containing at least two rings (e.g., substituted or unsubstituted naphthalenes or substituted or unsubstituted diphenyl ethers)), chelating agents, buffers, acids (e.g., 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., halogen 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 ingredient that the etching composition is "substantially free of" refers to an ingredient that is not intentionally added to the etching composition. In some embodiments, the etching compositions described herein may have up to about 1000 ppm (e.g., up to about 500 ppm, up to about 250 ppm, up to about 100 ppm, up to about 50 ppm, up to about 10 ppm, or up to about 1 ppm) of the etching composition being substantially free of one or more of the above components. In some embodiments, the etching compositions described herein may be completely free of one or more of the above components.

[0034] 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 mentioned 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, diammonium dihydrogen phosphate, bis(tetramethylammonium) hydrogen phosphate, disodium monohydrogen phosphate, sodium dihydrogen phosphate, dipotassium monohydrogen phosphate, potassium dihydrogen phosphate, ditetraalkylammonium monohydrogen phosphate, ditetraalkylammonium monohydrogen phosphate, diphosphonium monohydrogen phosphate, dihydrogen phosphonium phosphate, ammonium phosphonate, tetraalkylammonium phosphonate, sodium phosphonate, potassium phosphonate, phosphonium phosphonate, and combinations thereof.

[0035] 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 in a kit, each containing certain components of the etching compositions described herein.

[0036] In some embodiments, the disclosure features a method of etching a semiconductor substrate including a Si film (e.g., in a Si-containing feature). The method may include contacting a semiconductor substrate containing a Si film (e.g., a polycrystalline Si film) with an etching composition of the disclosure to substantially remove the Si film. In some embodiments, the semiconductor substrate may include a pattern or feature on a surface, and the Si film is part of the pattern or feature. In some embodiments, the method may further include rinsing the semiconductor substrate with a rinse solvent after the contacting step and / or drying the semiconductor substrate after the rinsing step.

[0037] In some embodiments, the method does not substantially remove dielectric materials (e.g., SiN, SiOx, or SiCO) in the semiconductor substrate. For example, the method does not remove more than about 5 wt% (e.g., more than about 3 wt% or more than about 1 wt%) of the metal conductor or dielectric material in the semiconductor substrate.

[0038] In some embodiments, the etching method includes the following steps:

[0039] (A) providing a semiconductor substrate including a Si film (e.g., a polycrystalline Si film in a pattern or feature);

[0040] (B) contacting the semiconductor substrate with an etching composition described herein;

[0041] (C) rinsing the semiconductor substrate with one or more suitable rinsing solvents; and

[0042] (D) Optionally, drying the semiconductor substrate (eg, by any suitable means to remove the rinse solvent without compromising the integrity of the semiconductor substrate).

[0043] The semiconductor substrate to be etched in this method may contain organic residues and organometallic residues and a range of metal oxides, some or all of which may also be removed during the etching process.

[0044] The semiconductor substrates (e.g., wafers) described herein are typically composed of silicon, silicon germanium, III-V compounds (such as GaAs), or any combination thereof. The semiconductor substrate may 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 and copper alloys, 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.

[0045] The semiconductor substrate may be contacted with the etching composition by any suitable method, such as placing the etching composition in a tank and dipping and / or immersing the semiconductor substrate into the etching composition, spraying the etching composition onto the semiconductor substrate, flowing the etching composition onto the semiconductor substrate, or any combination thereof.

[0046] The etching compositions disclosed herein 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.). The etching rate of Si increases as the temperature increases in this range, so processes using higher temperatures can be performed for shorter times. Conversely, lower etching temperatures generally require longer etching times.

[0047] Depending on the specific etching method, thickness and temperature used, the etching time can vary over a wide range. When etching in a batch immersion process, a suitable time range is, for example, up to about 10 minutes (e.g., about 1 minute to about 7 minutes, about 1 minute to about 5 minutes, or about 2 minutes to about 4 minutes). The etching time for a single wafer process can vary in the range of 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).

[0048] To further promote the etching ability of the etching composition of the present disclosure, mechanical agitation can be used. Examples of suitable agitation methods include circulating the etching composition over the substrate during the etching process, flowing the etching composition over the substrate or spraying the etching composition over the substrate, and ultrasonic or megasonic agitation. The orientation of the semiconductor substrate relative to the ground can be at any angle. Preferably, it is oriented horizontally or vertically.

[0049] After etching, the semiconductor substrate may be rinsed with a suitable 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, isopropanol, N-methylpyrrolidinone, γ-butyrolactone, dimethyl sulfoxide, ethyl lactate, and propylene glycol monomethyl ether acetate. Alternatively or in addition, an aqueous rinse solution having a pH>8 (such as a dilute aqueous ammonium hydroxide solution) may be used. The rinse solvent may be applied in a manner similar to that used when applying the etching composition described herein. The etching composition may have been removed from the semiconductor substrate before the rinsing step begins, or the etching composition may still be in contact with the semiconductor substrate at the beginning of the rinsing step. In some embodiments, the temperature used in the rinsing step is between 16°C and 27°C.

[0050] Optionally, the semiconductor substrate is dried after the rinsing step. Any suitable drying method known in the art may be used. Examples of suitable drying methods include spin drying, flowing a drying gas over the semiconductor substrate or heating the semiconductor substrate with a heating device such as a hot plate or infrared lamp, Maragoni drying, rotagoni drying, IPA drying, and any combination thereof. The drying time will depend on the specific method used, but is typically about 30 seconds to several minutes.

[0051] In some embodiments, the etching method described herein further includes forming a semiconductor device (eg, an integrated circuit device, such as a semiconductor chip) through the semiconductor substrate obtained by the method described above.

[0052] Although 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 what has been described and claimed.

[0053] Example

[0054] General Procedure 1

[0055] Formula Blending

[0056] Samples of etching compositions were prepared by adding the remaining components of the formulation to a calculated amount of solvent while stirring.

[0057] General Procedure 2

[0058] Materials and Methods

[0059] Blanket film etch rate measurements of the films were performed using commercially available unpatterned 300 mm diameter wafers that were segmented into 0.5" x 1.0" test coupons for evaluation. The primary blanket film materials used for testing included 1) a 100 mm thick film deposited on a silicon substrate. 1) a polycrystalline silicon (poly-Si) film deposited on a silicon substrate with a thickness of about 3) a SiN film deposited on a silicon substrate with a thickness of about 4) a SiN film deposited on a silicon substrate with a thickness of about of SiOx film.

[0060] The blanket film test coupons were measured for thickness before and after treatment to determine the blanket film etch rate. For poly-Si, SiN and SiOx blanket films, the film thickness was measured before and after treatment by ellipsometry using a Woollam VASE.

[0061] General Procedure 3

[0062] Etch evaluation using the beaker test

[0063] All blanket film etching tests were performed in a 150ml PFA bottle containing 100g of sample solution under continuous stirring at 250rpm. The PFA bottle was immersed in a 600mL glass beaker filled with water that served as a water bath. The beaker was placed on top of a hot stirring plate set at the desired temperature. All blanket test coupons with blanket films exposed to the sample solution on one side were cut into 0.5"×1.0" square test coupon sizes for beaker scale testing by a diamond scriber. Each individual test coupon was held in place using a single 4" long plastic locking tweezer. The test coupon, with one edge held by the locking tweezer, was suspended in a 150ml PFA bottle and immersed in 100g of the test solution while the solution was continuously stirred at 250rpm at 70°C or 75°C. The test coupon was kept static in the stirring solution until the treatment time (0.5 minutes or 60 minutes) had passed.

[0064] After the treatment time in the test solution had elapsed, 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, followed by immersion in 300 mL isopropyl alcohol (IPA) for 15 seconds with gentle agitation, and a final rinse was performed by immersion in 300 mL IPA for 15 seconds with gentle agitation. After the final IPA rinse step, all test coupons were subjected to a filtered nitrogen purge step using a handheld nitrogen blower, which vigorously removed all traces of IPA to produce a final dry sample for test measurement.

[0065] Example 1

[0066] Formulation Examples 1-16 (FE-1 to FE-16) and Comparative Formulation Examples 1-3 (CFE-1 to 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 the test coupons were immersed in the formulations for 0.5 minutes at 75°C, and the SiN and SiOx etch rates were measured after the test coupons were immersed in the formulations for 60 minutes at 75°C.

[0067] Table 1

[0068]

[0069] SA = sulfuric acid PA = phosphoric acid ER = etching rate

[0070] In Table 2, the poly-Si etching rate was measured after the test piece was immersed in the formulation at 70°C for 0.5 minutes, and the SiN and SiOx etching rates were measured after the test piece was immersed in the formulation at 70°C for 60 minutes. The SiN film with a thickness of about 1000 mm (film A) obtained the SiN etching rate of FE-5 to FE-10, and the SiN film with a thickness of about 1000 mm (film A) obtained the SiN etching rate of FE-5 to FE-10. The SiN etching rates of FE-11 to FE-16 were obtained for a SiN film (film B) having a thickness of .

[0071] Table 2

[0072]

[0073] SA = sulfuric acid PA = phosphoric acid BA = boric acid

[0074] PPA = phenylphosphonic acid PRA = propionic acid PLA = picolinic acid

[0075] MPA = Methylphosphonic acid ER = Etch rate

[0076] As shown in Tables 1 and 2, FE-1 to FE-16 (all of which include an acid different from the oxidant) exhibit improved poly-Si / SiN and / or poly-Sin / SiOx etch rate selectivity compared to CFE-1 to CFE-13 (none of which include an acid different from the oxidant).

Claims

1. An etching composition comprising: at least one quaternary ammonium hydroxide or a salt thereof; at least one oxidizing agent; at least one acid different from the at least one oxidizing agent; and water; in, The composition is substantially free of activators and organic solvents.

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

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

4. An etching composition comprising: at least one quaternary ammonium hydroxide or a 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.

5. The composition according to 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. The composition according to any one of claims 1 and 3 to 5, wherein The at least one quaternary ammonium hydroxide or salt thereof is present in an amount of about 1 wt % to about 15 wt % of the composition.

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

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

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

11. The composition according to any one of claims 1 to 10, wherein The amount of water is from about 80 wt % to about 99 wt % of the composition.

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

13. An etching composition comprising: 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.

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

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

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

17. The composition according to any one of claims 13 to 16, wherein The amount of water is from about 80 wt % to about 99 wt % of the composition.

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

19. A method comprising: A semiconductor substrate containing a Si film is brought into contact with the composition of any one of claims 1 to 18 to substantially remove the Si film.

20. The method of claim 19, wherein: The method does not substantially remove silicon oxide or silicon nitride.

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

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

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