Aqueous composition and cleaning method using same

Abstract

An aqueous composition includes (A) from 0.0001 to 10 mass % of one or more kinds of compounds selected from a C.sub.4-13 alkylphosphonic acid, a C.sub.4-13 alkylphosphonate ester, a C.sub.4-13 alkyl phosphate and a salt thereof, with respect to the total amount of the aqueous composition; and (B) from 0.0001 to 50 mass % of an acid other than the C.sub.4-13 alkylphosphonic acid, the C.sub.4-13 alkylphosphonate ester and the C.sub.4-13 alkyl phosphate or a salt thereof, with respect to the total amount of the aqueous composition.

Claims

1. An aqueous composition, comprising: (A) from 0.0001 to 10 mass % of at least one compound selected from the group consisting of a C.sub.4-13 alkylphosphonic acid, a C.sub.4-13 alkylphosphonate ester, a C.sub.4-13 alkyl phosphate and a salt thereof, with respect to a total amount of the aqueous composition; and (B) from 0.0001 to 50 mass % of an acid other than the C.sub.4-13 alkylphosphonic acid, the C.sub.4-13 alkylphosphonate ester and the C.sub.4-13 alkyl phosphate or a salt thereof, with respect to the total amount of the aqueous composition; wherein the C.sub.4-13 alkylphosphonic acid is present and comprises at least one selected from the group consisting of: n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-heptylphosphonic acid, n-octylphosphonic acid, n-nonylphosphonic acid, n-decylphosphonic acid, n-undecylphosphonic acid, n-dodecylphosphonic acid, and n-tridecylphosphonic acid, optionally in salt form thereof; and/or the C.sub.4-13 alkylphosphonate ester is present and comprises at least one selected from the group consisting of n-butylphosphonate ester, n-pentylphosphonate ester, n-hexylphosphonate ester, n-heptylphosphonate ester, n-octylphosphonate ester, n-nonylphosphonate ester, n-decylphosphonate ester, n-undecylphosphonate ester, n-dodecylphosphonate ester, and n-tridecylphosphonate ester, optionally in salt form thereof.

2. The aqueous composition according to claim 1, wherein the aqueous composition has a pH in a range of from 0 to 7.

3. The aqueous composition according to claim 1, wherein the acid or the salt thereof of Component (B) is hydrofluoric acid, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid or a salt thereof.

4. The aqueous composition according to claim 3, wherein the acid is hydrofluoric acid.

5. The aqueous composition according to claim 1, wherein the C.sub.4-13 alkyl phosphate is present and comprises at least one selected from the group consisting of: n-butyl phosphate, n-pentyl phosphate, n-hexyl phosphate, n-heptyl phosphate, n-octyl phosphate, n-nonyl phosphate, n-decyl phosphate, n-undecyl phosphate, n-dodecyl phosphate, n-tridecyl phosphate, 2-ethylhexyl phosphate, and isodecyl phosphate, optionally in salt form thereof.

6. The aqueous composition according to claim 1, wherein the C.sub.4-13 alkylphosphonic acid, the C.sub.4-13 alkylphosphonate ester or the C.sub.4-13 alkyl phosphate is present and comprise 2 or less alkyl chains.

7. The aqueous composition according to claim 6, wherein the C.sub.4-13 alkylphosphonic acid, the C.sub.4-13 alkylphosphonate ester or the C.sub.4-13 alkyl phosphate is present and comprise a single alkyl chain.

8. The aqueous composition according to claim 6, wherein the alkyl chain is linear.

9. The aqueous composition according to claim 1, further comprising a barium compound.

10. The aqueous composition according to claim 9, wherein the barium compound comprises at least one selected from the group consisting of barium nitrate, barium acetate, barium chloride and barium hydroxide.

11. A method for cleaning an electronic device, the method comprising: bringing the aqueous composition according to claim 1 into contact with the electronic device.

12. A method for producing an electronic device, the method comprising: bringing the aqueous composition according to claim 1 into contact with the electronic device.

13. An etching solution, comprising the aqueous composition according to claim 1.

14. A cleaning solution, comprising the aqueous composition according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 A cross-sectional schematic view of a semiconductor element of one embodiment before removing dry etch residue 1, the element comprising alumina at the bottom of the via and a structure including a zirconia-based hardmask 2, cobalt or a cobalt alloy 3, alumina 4, a low dielectric interlayer insulating film 5 and silicon nitride 6.

(2) FIG. 2 A cross-sectional schematic view of a semiconductor element of one embodiment before removing dry etch residue 1, the element comprising cobalt or a cobalt alloy at the bottom of the via and a structure including a zirconia-based hardmask 2, cobalt or a cobalt alloy 3, alumina 4, a low dielectric interlayer insulating film 5 and silicon nitride 6.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

(3) An aqueous composition of the present invention comprises:

(4) (A) 0.0001-10 mass % of one or more kinds of compounds selected from a C.sub.4-13 alkylphosphonic acid, a C.sub.4-13 alkylphosphonate ester, a C.sub.4-13 alkyl phosphate and a salt thereof, with respect to the total amount of the composition; and

(5) (B) 0.0001-50 mass % of an acid other than Component (A), that is, an acid other than the C.sub.4-13 alkylphosphonic acid, the C.sub.4-13 alkylphosphonate ester and the C.sub.4-13 alkyl phosphate or a salt thereof, with respect to the total amount of the composition.

(6) Herein, ranges indicating the contents of respective components are inclusive of the upper and lower values. For example, the above-mentioned range of the content of Component (A) is inclusive of 0.0001 mass % and 10 mass %.

(7) Hereinafter, an aqueous composition of the present invention will be described in detail.

(8) [Component (A): Alkylphosphonic Acids, Alkyl Phosphates and the Like]

(9) (A1) Alkylphosphonic Acids and Alkylphosphonate Esters

(10) An alkylphosphonic acid used in the present invention is a C.sub.4-13 alkylphosphonic acid having 4-13 carbon atoms (an alkylphosphonic acid having 4-13 carbon atoms). Such alkylphosphonic acids are known and commercially available (for example, available from Tokyo Chemical Industry Co., Ltd.). The alkylphosphonic acid is preferably a C.sub.5-11 alkylphosphonic acid, more preferably a C.sub.5-9 alkylphosphonic acid, and still more preferably a C.sub.6-8 alkylphosphonic acid. While the alkyl moiety of the alkylphosphonic acid may be either linear or branched, it is preferably linear. If the alkyl moiety of the alkylphosphonic acid is branched, the number of the branched chains is preferably 5 or less, more preferably 3 or less, and particularly preferably 1.

(11) In the aqueous composition of the present invention, an ester of the above-described alkylphosphonic acid may also be used. Specifically, an alkyl ester of the above-described C.sub.4-13 alkylphosphonic acid (an alkylphosphonic acid having 4-13 carbon atoms) may also be used.

(12) Where an alkylphosphonic acid can usually be represented by general formula R.sub.1P(═O)(OH).sub.2 (wherein, R.sub.1 is an alkyl group), an alkylphosphonate ester represented by general formula R.sub.1P(═O)(OR.sub.2).sub.2 (wherein, R.sub.1 is an alkyl group, and R.sub.2 is an alkyl group or a hydrogen atom: provided that at least one of the two R.sub.2 is an alkyl group) can also be used in the aqueous composition.

(13) Moreover, an alkylphosphonate ester as described herein also comprises an alkyl ester of a phosphonic acid (phosphonate ester). Specifically, a phosphonate ester represented by general formula R.sub.1P(═O)(OR.sub.2).sub.2 (wherein, R.sub.1 is hydrogen, R.sub.2 is an alkyl group or a hydrogen atom: provided that at least one of the two R.sub.2 is an alkyl group) can also be used herein as the alkylphosphonate ester in the aqueous composition.

(14) As can be appreciated from above, a compound represented by General formula (A) below is used as the alkylphosphonic acid or the alkylphosphonate ester in the aqueous composition.
R.sub.1P(═O)(OR.sub.2).sub.2  (A)

(15) (in General formula (A), R.sub.1 and R.sub.2 are each independently an alkyl group or a hydrogen atom: provided that at least one among R.sub.1 and the two R.sub.2 is an alkyl group).

(16) The alkylphosphonate ester used in the present invention is a C.sub.4-13 alkylphosphonate ester having a total of 4-13 carbon atoms (an alkylphosphonate ester having a total of 4-13 carbon atoms). The alkylphosphonate ester is preferably a C.sub.5-11 alkylphosphonate ester, more preferably a C.sub.5-9 alkylphosphonate ester and still more preferably a C.sub.6-8 alkylphosphonate ester. Furthermore, the alkyl chains of R.sub.1 and R.sub.2 in General formula (A) above each independently have carbon atoms of preferably 4-12, more preferably 6-11 and still more preferably 8-10.

(17) While the alkyl groups of the alkylphosphonate ester, namely, R.sub.1 and R.sub.2 in General formula (A) above, may be either linear or branched, they preferably contain linear alkyl groups.

(18) In addition, the number of alkyl chains in General formula (A) above, namely, the total number of the alkyl chains of R.sub.1 and R.sub.2, is preferably 2 or less. Specifically, while an alkylphosphonate ester in which both of R.sub.1 and R.sub.2 in General formula (A) R.sub.1P(═O)(OR.sub.2).sub.2 above are alkyl groups can be used, an alkylphosphonate ester in which R.sub.1 is an alkyl group while one or none of R.sub.2 is an alkyl group, an alkylphosphonate ester in which R.sub.1 is hydrogen while two or less of R.sub.2 is an alkyl group, or the like may be used. Still more preferably, an alkylphosphonic acid having only a single alkyl chain, that is, only one among R.sub.1 and the two R.sub.2 in General formula (A) R.sub.1P(═O)(OR.sub.2).sub.2 above is an alkyl group, is used. Particularly preferably, an alkylphosphonate ester in which only R.sub.1 in General formula (A) above is an alkyl group is used.

(19) The salt of the alkylphosphonic acid used in the present invention is a salt of the above-described alkylphosphonic acid, which is, for example, an ammonium salt, a tetramethylammonium salt, a tetraethylammonium salt, a tetrapropylammonium salt, a tetrabutylammonium salt, a lithium salt, a sodium salt, a potassium salt, a rubidium salt, a cesium salt, a beryllium salt, a magnesium salt, a calcium salt, a strontium salt, a barium salt or the like.

(20) Preferable examples of the alkylphosphonic acid or a salt thereof used in the present invention include n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-heptylphosphonic acid, n-octylphosphonic acid, n-nonylphosphonic acid, n-decylphosphonic acid, n-undecylphosphonic acid, n-dodecylphosphonic acid, n-tridecylphosphonic acid, a salt thereof or a mixture thereof.

(21) More preferable examples of the alkylphosphonic acid or a salt thereof that can be used include n-pentylphosphonic acid, n-hexylphosphonic acid, n-heptylphosphonic acid, n-octylphosphonic acid, n-nonylphosphonic acid, n-decylphosphonic acid, n-undecylphosphonic acid, a salt thereof and a mixture thereof.

(22) In addition, a salt of the above-described alkylphosphonate ester can also be used in the aqueous composition of the present invention. Examples of the salt of the alkylphosphonate ester include those corresponding to salts of the above-described alkylphosphonic acids.

(23) The concentration of the alkylphosphonic acid, the alkylphosphonate ester or the salt thereof in the aqueous composition can suitably be changed by considering the kind of the line material of the electronic device targeted for etching or cleaning and the kind of the masking material used in the etching step. The concentration of the alkylphosphonic acid, the alkylphosphonate ester or the salt thereof is preferably 0.0003-5 mass %, more preferably 0.0006-1 mass % and particularly preferably 0.001-0.5 mass % or 0.01-0.1 mass % with respect to the total amount of the composition.

(24) (A2) Alkyl Phosphates

(25) An alkyl phosphate used in the present invention is a C.sub.4-13 alkyl phosphate having 4-13 carbon atoms (an alkyl phosphate having 4-13 carbon atoms). Such alkyl phosphates are known and commercially available (for example, available from Tokyo Chemical Industry Co., Ltd.). The alkyl phosphate is preferably a C.sub.5-11 alkyl phosphate, more preferably a C.sub.5-9 alkyl phosphate, and still more preferably a C.sub.6-8 alkyl phosphate. While the alkyl moiety of the alkyl phosphate may be either linear or branched, it is preferably linear. If the alkyl moiety of the alkyl phosphate is branched, the number of the branched chains is preferably 5 or less, more preferably 3 or less, and particularly preferably 1.

(26) Other than a monoalkyl ester of phosphoric acid, a dialkyl ester or a trialkyl ester of phosphoric acid may also be used as the alkyl phosphate in the aqueous composition of the present invention. Specifically, not only a monoalkyl ester of phosphoric acid represented by General formula P(═O)(OR.sub.3).sub.3 (wherein, all of R.sub.3 are hydrogen atoms) in which only one of R.sub.3 is substituted with an alkyl group, but also a dialkyl ester in which two of R.sub.3 are substituted with alkyl groups and a trialkyl ester in which all of R.sub.3 are substituted with alkyl groups can be used in the aqueous composition of the present invention. However, the alkyl phosphate is preferably a dialkyl ester in which the number of alkyl chains is two or less (i.e., two of R.sub.3 in General formula P(═O)(OR.sub.3).sub.3 above are alkyl groups) or a monoalkyl ester (i.e., only one of R.sub.3 in General formula P(═O)(OR.sub.3).sub.3 above is an alkyl group), and more preferably a monoalkyl ester in which the number of the alkyl chain is 1. Specifically, the alkyl phosphate preferably has a single alkyl chain (an alkyl group represented by R.sub.3 above).

(27) Regardless of the number of ester bonds, the alkyl phosphate has a total of 4-13 carbon atoms. Regardless of the number of ester bonds, the alkyl phosphate is preferably a C.sub.5-11 alkyl phosphate, more preferably a C.sub.5-9 alkyl phosphate and still more preferably a C.sub.6-8 alkyl phosphate.

(28) Furthermore, the alkyl chain of R.sub.3 in General formula P(═O)(OR.sub.3).sub.3 above has carbon atoms of preferably 4-12, more preferably 6-11 and still more preferably 8-10. While the alkyl groups of the alkyl phosphate, namely, R.sub.3 in General formula P(═O)(OR.sub.3).sub.3 above, may be either linear or branched, they are preferably linear.

(29) The salt of the alkyl phosphate used in the present invention is a salt of the above-described monoalkyl ester or dialkyl ester of phosphoric acid, which is, for example, an ammonium salt, a tetramethylammonium salt, a tetraethylammonium salt, a tetrapropylammonium salt, a tetrabutylammonium salt, a lithium salt, a sodium salt, a potassium salt, a rubidium salt, a cesium salt, a beryllium salt, a magnesium salt, a calcium salt, a strontium salt, a barium salt or the like.

(30) Preferable examples of the alkyl phosphate or a salt thereof used in the present invention include n-butyl phosphate, n-pentyl phosphate, n-hexyl phosphate, n-heptyl phosphate, n-octyl phosphate, n-nonyl phosphate, n-decyl phosphate, n-undecyl phosphate, n-dodecyl phosphate, n-tridecyl phosphate, 2-ethylhexyl phosphate, isodecyl phosphate, a salt thereof or a mixture thereof.

(31) More preferable examples of the alkyl phosphate or a salt thereof that can be used include n-pentyl phosphate, n-hexyl phosphate, n-heptyl phosphate, n-octyl phosphate, n-nonyl phosphate, n-decyl phosphate, n-undecyl phosphate, 2-ethylhexyl phosphate, isodecyl phosphate, a salt thereof and a mixture thereof.

(32) The concentration of the alkyl phosphate or a salt thereof in the aqueous composition can suitably be changed by considering the kind of the line material of the electronic device targeted for etching or cleaning and the kind of the masking material used in the etching step. The concentration of the alkyl phosphate or a salt thereof is in a range of preferably 0.0003-5 mass %, still more preferably 0.0006-1 mass % and particularly preferably 0.001-0.5 mass % or 0.01-0.1 mass % with respect to the total amount of the composition.

(33) [Component (B): Acid Other than Component (A)]

(34) An acid used in the aqueous composition of the present invention may be either inorganic or organic acid other than Component (A). Specifically, examples of the acid used in the aqueous composition include acids other than C.sub.4-13 alkylphosphonic acids, C.sub.4-13 alkylphosphonate esters which are partial esters and also acids and C.sub.4-13 alkyl phosphates. In addition, a salt of an acid other than Component (A) may also be used in the aqueous composition.

(35) Examples of the inorganic acids that may be used in the present invention include hydrofluoric acid, nitric acid, sulfuric acid, hydrochloric acid and phosphoric acid. Among them, hydrofluoric acid is preferable, since the performance of removing a dry etch residue in a low-pH area can be enhanced by the use of hydrofluoric acid.

(36) Examples of the organic acids that can be used in the present invention include C.sub.1-18 aliphatic carboxylic acids, C.sub.6-10 aromatic carboxylic acids as well as C.sub.1-10 amino acids.

(37) Preferable examples of the C.sub.1-18 aliphatic carboxylic acids include formic acid, acetic acid, propionic acid, lactic acid, glycolic acid, diglycolic acid, pyruvic acid, malonic acid, butyric acid, hydroxybutyric acid, tartaric acid, succinic acid, malic acid, maleic acid, fumaric acid, valeric acid, glutaric acid, itaconic acid, adipic acid, caproic acid, adipic acid, citric acid, propanetricarboxylic acid, trans-aconitic acid, enanthic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid.

(38) Preferable examples of the C.sub.6-10 aromatic carboxylic acids include benzoic acid, salicylic acid, mandelic acid, phthalic acid, isophthalic acid and terephthalic acid.

(39) Furthermore, preferable examples of the C.sub.1-10 amino acids include carbamic acid, alanine, glycine, asparagine, aspartic acid, sarcosine, serine, glutamine, glutamic acid, 4-aminobutyric acid, iminodibutyric acid, arginine, leucine, isoleucine and nitrilotriacetic acid.

(40) The amount of the acid contained in the composition is 0.0001-50 mass %, preferably 0.0005-20 mass %, more preferably 0.001-10 mass % and still more preferably 0.01-1 mass %. Particularly preferably, it is 0.02-1 mass %.

(41) [Component (C): Water]

(42) The composition of the present invention is aqueous and contains water as a diluent. While the water of the present invention is not particularly limited, it is preferably water that has been removed of metal ions, organic impurities, particles and the like by distillation, an ion exchange treatment, a filter treatment, any adsorption treatment or the like, and is particularly preferably pure water or ultrapure water.

(43) The amount of water contained in the composition is usually 40-99.9998 mass % and preferably, 89.5-99.998 mass %.

(44) [Component (D): Barium Compound]

(45) An aqueous composition of the present invention may contain a barium compound. The barium compound used in the present invention is an inorganic matter containing barium, which has an effect of preventing corrosion of alumina.

(46) Examples of the barium compound include barium nitrate, barium acetate, barium chloride, barium hydroxide, barium sulfite, barium chlorate, barium perchlorate, barium peroxide, barium chromate, barium oxide, barium cyanide, barium bromide, barium carbonate, barium metaborate, barium iodide, barium tetrafluoroborate, barium sulfate, barium sulfide and a salt generated via reaction between barium hydroxide and an acid, where one or more kinds of them can be used alone or in combination.

(47) Among them, barium nitrate, barium acetate, barium chloride and barium hydroxide are favorable for they are highly soluble in water and readily available.

(48) The concentration of the barium compound in the composition is 0.00005-10 mass %, preferably 0.00025-5 mass %, still more preferably 0.001-2 mass % and particularly preferably 0.002-1 mass %. As long as the concentration is in this range, damage to alumina can be suppressed effectively.

(49) [Other Components]

(50) If necessary, the aqueous composition of the present invention may be added with an additive that is conventionally used in aqueous compositions for semiconductors as long as it does not interfere with the purpose of the present invention.

(51) For example, alkali (for example, ammonia), a chelating agent, a surfactant, a defoamer, an oxidant, a reductant, an anti-corrosive agent for metals, a water-soluble organic solvent or the like may be added as additives. These additives are known and described, for example, in Japanese Unexamined Patent Application Publication (translation of PCT) No. 2013-533631.

(52) [Method for Preparing Aqueous Composition (Liquid Composition)]

(53) The aqueous composition (liquid composition) of the present invention can be prepared by agitating the above-described Component (A), the above-described Component (B), water, and if necessary, the above-described Component (D) and the above-described other components, until homogeneous.

(54) While the range of the pH of the aqueous composition of the present invention is not particularly limited, it is usually 0-7, preferably 0-6, more preferably 0-5 and still more preferably 0-4.

(55) An aqueous composition in a preferred aspect of the present invention is capable of efficiently removing dry etch residues while preventing corrosion of cobalt, alumina and the like.

(56) [Method of Using Aqueous Composition: Method for Cleaning/Producing Electronic Device]

(57) When used as an aqueous composition for cleaning (hereinafter, also referred to as a “cleaning solution”), an aqueous composition of the present invention can remove dry etch residues by making contact with an electronic device (for example, a semiconductor element) in a wet etching step (or in a step prior to or following said step). As a method for bringing the composition into contact with the device, for example, a cleaning solution may be placed in a cleaning container so that an electronic device targeted for cleaning can be immersed in the cleaning solution to remove the dry etch residues, thereby cleaning the electronic device. Alternatively, an electronic device can be subjected to a treatment in a single-wafer cleaning mode to remove the dry etch residues, thereby cleaning the electronic device. Besides a dry etch residue removing solution (a cleaning solution), the aqueous cleaning composition can also favorably be used as an etching solution. In addition, the aqueous composition can also be used as a cleaning solution for cleaning the electronic device after a step of chemical-mechanical polishing (CMP).

(58) Hence, an aqueous composition of the present invention may favorably be used in a cleaning method that comprises a step of cleaning an electronic device, and a method for producing an electronic device comprising such step.

(59) The temperature of the cleaning solution of the present invention upon use is usually 10-80° C., preferably 15-70° C., more preferably 20° C.-65° C. and particularly preferably 20° C.-60° C. The temperature may suitably be selected according to the conditions of cleaning and the electronic device used (for example, a semiconductor element).

(60) The cleaning solution of the present invention is usually used for 0.2-60 minutes. The time may suitably be selected according to the conditions of cleaning and the electronic device used (for example, a semiconductor element). A rinse solution used following the cleaning solution of the present invention may be an organic solvent, water, carbonated water or ammonia water.

(61) [Electronic Devices Targeted for Cleaning/Production]

(62) An electronic device targeted for cleaning and production employing the present invention is, for example, a semiconductor element or a display element, where a target for cleaning is usually an intermediate product that is obtained after a dry etching process. A semiconductor element or a display element is a substrate material such as silicon, amorphous silicon, polysilicon or glass, an insulating material such as silicon oxide, silicon nitride, silicon carbide or a derivative thereof, a material such as cobalt, a cobalt alloy, tungsten or titanium-tungsten, a compound semiconductor such as gallium-arsenic, gallium-phosphorus, indium-phosphorus, indium-gallium-arsenic or indium-aluminum-arsenic, or an oxide semiconductor such as chromium oxide. The electronic device targeted for cleaning by the present invention is particularly preferably an element using a cobalt or cobalt alloy line material, a zirconia-based hardmask and a low dielectric interlayer insulating film.

(63) Dry etch residues targeted by the present invention are, for example, those that are generated upon forming a via or trench structure in a low dielectric interlayer insulating film by dry etching using a zirconia-based hardmask as a mask. Some of the dry etch residues are generated when etching gas makes contact with the zirconia-based hardmask. In this case, naturally, the targeted dry etch residue contains zirconium.

EXAMPLES

(64) Hereinafter, the present invention will be described specifically by means of examples. The embodiments, however, can suitably be modified as long as the advantage of the present invention is attained.

(65) Unless otherwise specified, “%” refers to “mass %”.

(66) [Wafer Used for Evaluation]

(67) <Evaluation Wafer A>: Wafer for Evaluating Removal of Dry Etch Residue

(68) Silicon nitride, an interlayer insulating film, silicon nitride, zirconia and a photoresist were sequentially formed from the bottom into a film, and then a photoresist was patterned thereon.

(69) The predetermined part of the hardmask was removed by dry etching using the photoresist as a mask, and the photoresist was removed by oxygen plasma ashing. Furthermore, a via was formed in the silicon nitride and the interlayer insulating film by dry etching using the hardmask as a mask.

(70) <Filmed Wafers>: Wafers for Evaluating Damage to Cobalt and Alumina

(71) Wafers on which cobalt or alumina was formed into a film were prepared under the following film forming conditions.

(72) (1) Cobalt: formed into a film to a thickness of 2000 Å on Si by physical vapor deposition.

(73) (2) Alumina: formed into a film to a thickness of 1000 Å on Si by physical vapor deposition.

(74) [Evaluation Method]

(75) <Removal of Dry Etch Residues>

(76) Evaluation wafers A that were treated with various aqueous compositions (cleaning solutions) were observed by SEM.

(77) Instrument used for measurement; Ultra-high resolution field emission scanning electron microscope SU9000 (100,000× magnification) available from Hitachi High-Tech Corporation

(78) Evaluation criteria:

(79) E: Dry etch residue was completely removed.

(80) G: Dry etch residue was almost completely removed.

(81) P: Removal of dry etch residue was insufficient.

(82) Evaluations E and G were found to be acceptable.

(83) <Film Thickness>

(84) The film thicknesses of the filmed wafers were measured using a x-ray fluorescence spectrometer SEA1200VX available from SII NanoTechnology (Film thickness measuring instrument A) or an optical film thickness gauge n&k 1280 available from n&k technology, Inc (Film thickness measuring instrument B). The film thicknesses of the cobalt-filmed wafer and the alumina-filmed wafer were measured using Film thickness measuring instruments A and B, respectively.

(85) <E.R. (Etch Rate)>

(86) Each of the filmed wafers was treated with a cleaning solution, and the difference in the film thicknesses before and after the treatment was divided by the treatment time to determine E.R.

(87) E.R. of 1 Å/min or less for cobalt and E.R. of 25 Å/min or less for alumina were found to give satisfying products.

(88) <Measurement of pH Value>

(89) The pH value of the aqueous composition in each of the examples and the reference examples was measured at 25° C. using a pH meter (pH meter F-52 available from Horiba, Ltd.).

Examples 1-31

(90) Evaluation wafer A and the respective filmed wafers were used for the test. The wafers were immersed in the cleaning solutions indicated in Tables 1 and 2 at the treatment temperatures indicated in Tables 1 and 2, and subsequently rinsed with ultrapure water and dried by dry nitrogen gas blowing. Evaluation wafers A were treated for 5 minutes, and the treated wafers were observed by SEM.

(91) As to the respective filmed wafers, the cobalt-filmed wafer and alumina were treated for 30 and 5 minutes, respectively. E.R. was calculated from the film thicknesses before and after the treatment.

Examples 1-31 and Reference Examples 1-23

(92) Evaluation wafer A, the cobalt-filmed wafer and the alumina-filmed wafer were used for the test. The wafers were immersed in the aqueous compositions (cleaning solutions) indicated in Tables 1, 2 and 3 at 20° C. or 50° C. (see the treatment temperatures in the tables), and subsequently rinsed with ultrapure water and dried by dry nitrogen gas blowing. Evaluation wafers A were all immersed for 5 minutes, and the treated wafers were observed by SEM.

(93) The cobalt-filmed wafer and the alumina-filmed wafer were treated for 30 and 5 minutes, respectively. E.R. was calculated from the film thicknesses before and after the treatment.

(94) In Examples 1-31, damage to cobalt was found to be prevented.

(95) Meanwhile, the reference examples shown in Table 3 were found to be not so favorable for the purpose of suppressing damage to cobalt.

(96) In addition, the compositions containing HF shown in Tables 1 and 2 were found to remove dry etch residues contained in Evaluation wafer A.

(97) Furthermore, in the examples shown in Table 2, compositions containing a barium compound were found to prevent damage to alumina.

(98) TABLE-US-00001 TABLE 1 Composition Evaluation Treatment Alkylphosphonic Removal of temperature/ acid or alkyl Water Cobalt E.R. dry etch Example ° C. phosphate/mass % Acid/mass % Others (mass %) (mass %) pH (Å/min) residue 1 20 N-decylphosphonic 0.01 HF 0.1 99.89 2.9 0.3 G acid 2 20 N-hexylphosphonic 0.1 HF 0.1 99.8 2.9 0.2 E acid 3 20 N-octylphosphonic 0.01 HF 0.1 99.89 3.0 0.1 E acid 4 20 Ammonium 0.001 HF 0.1 99.899 2.9 0.5 E n-dodecyl phosphate 5 20 N-dodecylphosphonic 0.01 HF 0.1 99.89 3.0 0.2 G acid 6 20 Ammonium 0.01 HF 0.1 99.89 3.0 0.4 G n-decylphosphonate 7 20 Sodium 0.01 HF 0.1 99.89 2.8 0.1 G n-decylphosphonate 8 20 Potassium 0.01 HF 0.1 99.89 2.8 0.5 G n-decylphosphonate 9 20 Ammonium 0.01 Sulfuric acid 0.01 99.98 3.0 0.4 — n-decylphosphonate 10 20 Ammonium 0.01 Nitric acid 0.01 99.98 3.0 0.3 — n-decylphosphonate 11 20 Ammonium 0.5 Nitric acid 1 98.5 0.9 0.2 — n-hexylphosphonate 12 20 Ammonium 0.01 Hydrochloric 0.01 99.98 3.0 0.2 — n-decylphosphonate acid 13 20 Ammonium 0.5 Phosphoric 0.01 99.49 3.3 0.1 — n-hexylphosphonate acid 14 20 Ammonium 0.01 Acetic acid 0.01 99.98 3.9 0.4 — n-decylphosphonate 15 20 N-octylphosphonic 0.01 HF 0.054 Ammonia (0.046) 99.89 6.5 0.2 — acid 16 50 N-octylphosphonic 0.01 HF 0.054 Ammonia (0.046) 99.89 6.5 0.5 G acid 17 20 Ammonium 0.01 HF 0.1 Ammonia (0.05) 99.84 3.8 0.2 — n-decylphosphonate 18 50 Ammonium 0.01 HF 0.1 Ammonia (0.05) 99.84 3.8 0.5 E n-decylphosphonate 19 20 Ammonium 0.15 Acetic acid 10 89.85 2.6 0.1 — n-hexylphosphonate 20 20 N-octylphosphonic 0.01 Nitric acid 0.001 99.989 4.2 0.2 — acid 21 20 N-octylphosphonic 0.01 HF 1 98.99 1.3 0.5 E acid 22 20 N-octylphosphonic 0.001 HF 0.02 99.979 3.0 0.8 G acid 23 20 2-Ethylhexyl 0.01 HF 0.1 99.89 2.8 0.1 — phosphate 24 20 Isodecyl 0.01 HF 0.1 99.89 2.9 0.2 — phosphate

(99) TABLE-US-00002 TABLE 2 Composition Evaluation Treatment Alkylphosphonic Removal of temperature/ acid or alkyl Water Cobalt E.R. dry etch Alumina E.R. Example ° C. phosphate/mass % Acid/mass % Others (mass %) (mass %) pH (Å/min) residue (Å/min) 3 20 N-octylphosphonic 0.01 HF 0.1 99.89 3.0 0.1 E 56 acid 25 20 N-octylphosphonic 0.01 HF 0.1 Ammonia (0.05) 99.84 3.9 0.2 E 47 acid 26 20 N-octylphosphonic 0.01 HF 0.1 Ammonia (0.085) 99.805 4.5 0.2 G 28 acid 27 20 N-octylphosphonic 0.01 HF 0.1 Barium nitrate (1) 98.89 3.0 0.6 E 3 acid 28 20 N-octylphosphonic 0.01 HF 0.1 Barium hydroxide 99.79 3.3 0.5 E 2 acid octahydrate (0.1) 29 20 N-octylphosphonic 0.01 HF 0.1 Barium chloride 99.79 3.1 0.2 E 2 acid (0.1) 30 20 N-octylphosphonic 0.01 HF 0.1 Ammonia (0.05) 99.838 4.0 0.3 E 23 acid Barium nitrate (0.002) 31 20 N-octylphosphonic 0.01 HF 0.1 Ammonia (0.085) 99.803 4.5 0.3 G 12 acid Barium nitrate (0.002)

(100) TABLE-US-00003 TABLE 3 Treatment Composition Evaluation Reference temperature/ Alkylphosphonic acid or alkyl Water Cobalt E.R. example ° C. phosphate/mass % Acid/mass % Others (mass %) (mass %) pH (Å/min) 1 20 HF 0.1 99.9 2.9 31.0 2 20 HF 0.1 Ammonia (0.05) 99.85 3.9 32.0 3 20 HF 0.1 Ammonia (0.85) 99.815 4.5 31.0 4 20 HF 0.054 Ammonia (0.046) 99.9 7.3 20.0 5 20 Sulfuric acid 0.01 99.99 3.0 32.0 6 20 Nitric acid 0.01 99.99 3.2 45.0 7 20 Nitric acid 1 99 0.9 45.0 8 20 Hydrochloric acid 0.01 99.99 3.3 47.0 9 20 Phosphoric acid 0.01 99.99 3.5 25.0 10 20 Acetic acid 0.01 99.99 3.9 9.0 11 20 N-propylphosphonic 0.1 HF 0.1 99.8 2.8 19.0 acid 12 20 Ammonium 0.001 HF 0.1 99.899 2.9 8.0 n-tetradecaphosphonate 13 20 Phenylphosphonic 0.1 HF 0.1 99.8 2.8 11.0 acid 14 20 N-butanethiol 0.1 HF 0.1 99.8 2.9 6.0 15 20 N-octanoic acid 0.1 HF 0.1 99.8 2.8 6.0 16 20 Sodium 0.1 HF 0.1 99.8 2.8 33.0 n-decanesulfonate 17 20 N-octylamine 0.1 HF 0.1 99.8 3.3 29.0 18 20 N-hexanol 0.1 HF 0.1 99.8 2.9 34.0 19 20 5-Methyl-1H- 0.1 HF 0.1 99.8 3.0 6.7 benzotriazole 20 20 Acetic acid 10 90 2.6 14.0 21 20 Nitric acid 0.001 99.999 4.2 6.0 22 20 HF 1 99 1.2 38.0 23 20 HF 0.02 99.98 2.8 45.0

INDUSTRIAL APPLICABILITY

(101) The aqueous composition in a preferred aspect of the present invention has a favorable effect in preventing corrosion of cobalt or a cobalt alloy even in a low-pH area (for example, 4 or less).

(102) In addition, the aqueous composition (for example, a composition added with hydrogen fluoride) in a preferred aspect of the present invention has a favorable effect in preventing corrosion of cobalt or a cobalt alloy and also has a favorable effect in removing etch residues.

(103) Since an etching solution, a cleaning solution and a cleaning method in a preferred aspect of the present invention have a favorable effect in preventing corrosion of a line material such as cobalt and have a favorable effect in removing dry etch residues, they allow production of a high precision, high quality electronic device such as a semiconductor element at high yield in a production process of said electronic device.

DESCRIPTION OF REFERENCE NUMERALS

(104) 1 Zirconia-based dry etch residue 2 Zirconia-based hardmask 3 Cobalt or cobalt alloy 4 Alumina 5 Low dielectric interlayer insulating film 6 Silicon nitride (SiN)