JP2002155382A - Etchant for ti-base film and etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching method for Ti-base films and an etchant used in etching of the Ti-base films. SOLUTION: The etching method consisting of etching the Ti-base films on a semiconductor substrate by using a solution containing hydrogen peroxide and a chelate agent and the etchant for the Ti-base films on the semiconductor substrate consisting of the solution containing the hydrogen peroxide and the chelate agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing of a semiconductor substrate, and more particularly to an etching method and an etching agent for a Ti-based film such as a Ti film and a TiW alloy film.

[0002]

2. Description of the Related Art Conventionally, etching of a Ti-based film such as Ti or TiW has been performed.
RIE (rear) that can be anisotropically etched
Active ion etching) method is mainly used.
You. In the RIE method, particularly the parallel plate type RIE method, usually,
Cl as etching gas _Two, BCl_Three, HBr, etc.
Halogen compounds are used as masks to protect patterns
Is a general-purpose positive type resist, pressure 50mTo
rr (6.7 Pa), RF-POWER 250W, group
Dry etching is performed at a plate temperature of 60 ° C.

However, the problem in this case is that the etching selectivity with respect to the resist to be used (the ratio of the etching rate of the material to be etched to the photoresist and the underlying material of the material to be etched) becomes small and there is no margin in the process margin. In addition, a desired etching pattern cannot be obtained because a photoresist mask for protecting the pattern disappears, and a TiW film is an alloy used in a high-temperature sputtering method, and residues are easily generated in dry etching.

[0004] Moreover, Ti-based films generally have the disadvantage that the etching rate is lower than that of Al-based films and that the throughput is poor, and the RIE method is expensive.
It also has economic disadvantages such as the need to use the device.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to improve the etching selectivity so that no etching residue is generated and the resist surface and the underlying film are not damaged. Providing an etching method for a Ti-based film and an etching agent used for etching the Ti-based film, and furthermore, an economical drawback that requires an expensive dry etching apparatus by applying an inexpensive wet etching method. Is to overcome.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a method for forming Ti on a semiconductor substrate using a solution containing hydrogen peroxide and a chelating agent.
The present invention relates to an etching method characterized by performing etching of a base film.

Further, the present invention relates to an etching agent for a Ti-based film on a semiconductor substrate comprising a solution containing hydrogen peroxide and a chelating agent.

Further, the present invention comprises a solution containing hydrogen peroxide, an alkane polyphosphonic acid which may have a hydroxy group, and ammonium borate, and a solution containing ammonia. Is to mix these solutions and reach a final concentration of 15 to 25 hydrogen peroxide.
% By weight, 0.01 to 6% by weight of alkane polyphosphonic acids optionally having a hydroxy group, 0.01% of ammonia
-20% by weight, and ammonium borate 0.01-10
% Ti used as an etchant comprising
The present invention relates to an etching agent for a base film.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, the etching selectivity can be improved by etching a Ti-based film using a solution containing hydrogen peroxide and a chelating agent. It is possible to obtain a desired pattern because it is possible to obtain an effect such that an etching residue is not generated even in an alloy film formed by a high-temperature sputtering method in order to use a chemical dissolution reaction for etching. It is possible to solve the problems in the conventional method as described above, and furthermore, if the solution of the present invention is used, batch processing by the wet etching method using the solution is possible, which is compared with the dry etching method of single wafer processing. As a result, it has been found that effects such as improvement in throughput and inexpensive equipment costs can be obtained, and that productivity and economy can be significantly improved, and the present invention has been completed.

In the present invention, a Ti-based film refers to a film formed on a substrate using Ti or a Ti alloy such as TiW.

[0011] The hydrogen peroxide according to the present invention may be a Ti film or a Ti film.
It is used for the purpose of oxidizing a W alloy film or the like and facilitating a dissolution reaction with an alkali compound. The concentration of hydrogen peroxide used is usually 15 to 25 as the concentration in the solution according to the present invention.
%, Preferably 18 to 23% by weight.

In the present invention, the chelating agent functions to prevent decomposition of hydrogen peroxide, maintain oxidizing power, and coordinate with Ti together with hydrogen peroxide to form a water-soluble complex, thereby dissolving Ti. Is used. As the chelating agent, those usually used in this field may be used. For example, an alkyliminopolycarboxylic acid [hydroxyethyliminodiacetic acid (HID) which may have a hydroxy group may be used.
A), iminodiacetic acid (IDA) etc.], nitrilopolycarboxylic acid [nitriotriacetic acid (NTA), nitrilotripropionic acid (NTP) etc.], a hydroxyalkyl group, a hydroxyaryl group or a hydroxyaralkyl group. Mono or polyalkylene polyamine polycarboxylic acids [ethylenediaminetetraacetic acid (EDTA), ethylenediaminediacetic acid (EDDA), ethylenediaminedipropionic acid dihydrochloride (EDDP), hydroxyethylethylenediaminetriacetic acid (EDTA-OH), 1,6 -Hexamethylenediamine-N, N, N ', N'-tetraacetic acid (HDTA), triethylenetetramine hexaacetic acid (TTHA), diethylenetriamine-N, N, N', N '', N ''-pentaacetic acid ( DTPA), N, N-bis (2-hydroxybenzyl) ethylenediamine-N, N-diacetic acid (HBED), etc., polyamino Le Kang polycarboxylic acids [diaminopropane tetraacetic acid (Methyl-EDT
A,), trans-1,2-diaminocyclohexane-N, N, N ', N'
-Tetraacetic acid (CyDTA), etc.), polyaminoalkanolpolycarboxylic acid [diaminopropanoltetraacetic acid (DPT
A-OH) and the like, and hydroxyalkyl ether polyamine polycarboxylic acids [glycol ether diamine tetraacetic acid (GEDTA) and the like] and the like. Nitrogen-containing polyalkylene having 1 to 4 nitrogen atoms and 2 to 6 carboxyl groups in the molecule. Carboxylic acids such as aminopoly (alkylphosphonic acid) [aminotris (methylenephosphonic acid) and the like], nitrilopoly (alkylphosphonic acid) [nitrilotris (methylenephosphonic acid) (NTPO) and the like], mono- or polyalkylenepolyaminepoly (alkylphosphonic acid) Acid) [ethylenediaminetetrakis (methylenephosphonic acid) (EDTP
O), ethylenediamine-N, N'-bis (methylenephosphonic acid) (EDDPO), isopropylenediaminetetrakis (methylenephosphonic acid), diethylenetriamine-N,
N, N ′, N ″, N ″ -penta (methylenephosphonic acid), ethylenediaminebis (methylenephosphonic acid), hexenediaminetetrakis (methylenephosphonic acid), etc., alkylaminopoly (alkylphosphonic acid) [ethylamino Bis (methylenephosphonic acid), dodecylaminobis (methylenephosphonic acid), etc.] and nitrogen-containing polyphosphonic acids having 1 to 3 nitrogen atoms and 2 to 5 phosphonic acid groups in the molecule, such as methyldiphosphonic acid , Ethylidene diphosphonic acid, 1-hydroxyethylidene-1,1'-diphosphonic acid (HE
Alkane polyphosphonic acids optionally having a hydroxy group such as DPO), 1-hydroxypropylidene-1,1′-diphosphonic acid, 1-hydroxybutylidene-1,1′-diphosphonic acid, for example, dihydroxyethylglycine (DHEG),
N-substituted amino acids such as N-acetylglycine; amides such as benzylamide; alkylenediamines such as ethylenediamine, propylenediamine, isopropylenediamine, and butylenediamine; polyalkanolamines such as triethanolamine such as diamino Aromatic diamines such as benzene and diaminonaphthalene, for example, polyalkylenepolyamines such as diethylenetriamine, dipropylenetriamine, and triethylenetetraamine; condensed phosphoric acids such as tripolyphosphoric acid and hexametaphosphoric acid; alkanoyls such as acetylacetone and hexafluoroacetylacetone Ketones such as halide ions (F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ ),
Inorganic ions having a complex forming ability such as cyanide ion, thiocyanate ion, thiosulfate ion, and ammonium ion are exemplified. Among these chelating agents, nitrogen-containing polyphosphonic acids having 1 to 3 nitrogen atoms and 2 to 5 phosphonic acid groups in the molecule, and hydroxy groups are preferred in consideration of stability in the presence of hydrogen peroxide. Polyphosphonic acids such as alkane polyphosphonic acids which may be substituted are preferred, and polyphosphonic acids such as alkane polyphosphonic acids which may have a hydroxy group are particularly preferred.
More specifically, nitrilotris (methylene phosphonic acid), 1-hydroxyethylidene-1,1′-diphosphonic acid,
1-Hydroxypropylidene-1,1'-diphosphonic acid and 1-hydroxybutylidene-1,1'-diphosphonic acid are preferred. Among them, 1-hydroxyethylidene-1,1'-diphosphonic acid and 1-hydroxypropyl Lydene-1,1′-diphosphonic acid and 1-hydroxybutylidene-1,1′-diphosphonic acid are particularly preferred. The concentration of the chelating agent used is usually 0.01 to 6% by weight, preferably 0.1 to 5% by weight, more preferably 1 to 3% by weight as the concentration in the solution according to the present invention.

The solution (etchant according to the present invention) used in the present invention contains at least hydrogen peroxide and a chelating agent, and the solution usually has a pH of 7.
It is adjusted and maintained in the range of 2 to 10, preferably 8 to 10. For the purpose of maintaining the pH of the solution in this range, it is usually preferable to use a buffer.

The buffer used in the present invention is not particularly limited as long as it is commonly used in this field.
Ammonia, for example, ammonium salts of inorganic acids such as ammonium chloride, ammonium nitrate, ammonium fluoride and ammonium borate are preferred, and these may be used alone or in combination of two or more. When this ammonium salt is used, the salt itself may be directly added to the solution according to the present invention, or an acid capable of forming the salt in the solution and ammonia may be separately added to the solution. May be added. More specifically, ammonia and hydrochloric acid, nitric acid,
An inorganic acid such as hydrofluoric acid and boric acid or a salt thereof (for example, an alkali metal salt such as sodium, potassium, and lithium (specifically, for example, sodium tetraborate)) is separately present in the reaction system. In this case, if ammonia is used in excess with respect to the acid or its alkali metal salt, as a result, both the ammonium salt of the inorganic acid and ammonia coexist in the reaction system. Among these, ammonia and an inorganic acid, especially ammonia and boric acid, are added to the solution according to the present invention, or ammonia and an ammonium salt of an inorganic acid, especially ammonia and an ammonium salt of boric acid are added to the solution. It is preferred to add.
The concentration of these buffers may vary depending on the type of buffer used and the like, but cannot be specified unconditionally. 10% by weight, preferably 0.1%.
It is from 0.05 to 6% by weight, more preferably from 0.1 to 5% by weight. When ammonia and an ammonium salt are used in combination, the amount of the ammonium salt is the same as above,
The amount of ammonia is usually 0.01 to 20% by weight, preferably 0.05 to 12% by weight, more preferably 0.1 to 10% by weight as the concentration in the solution according to the present invention.

In the method of the present invention, when etching the TiW-based film on the semiconductor substrate using the solution according to the present invention (the etching agent according to the present invention), it is preferable to perform the etching under alkaline conditions. . That is, as shown in Equations 1 and 2 below, tungsten (W) is oxidized with hydrogen peroxide to produce tungsten oxide (WO ₃ ). Since WO ₃ is soluble in alkali, it reacts with alkali to dissolve tungstate ions (W
O ₄ ^2- ). Ti also acts with hydrogen peroxide and a chelating agent in the alkaline region, and as shown in Formula 3,
[TiO (H ₂ O ₂ ) EDTA] ^2- complex is formed. TiW
It is considered that the etching of the alloy film is also progressing by the reactions represented by the formulas 1 to 3. FIG. 1 shows changes in pH and etching time at this time.

As is apparent from the results shown in FIG. 1, the etching tends to proceed in a shorter time as the pH becomes higher in the alkali region. That is, it is preferable to perform etching in an alkaline region, and as a specific pH range,
For example, usually 7.2 to 10, preferably 7.8 to 9.8,
It is found that the pH is more preferably 8.2 to 9.2.
At a pH lower than the above range, although it does not affect the pattern formation, it takes a little time for the etching to proceed, and a pH higher than the pH range is used.
In this case, although the etching does not require a long time, the resist which is a protection mask for the pattern is dissolved and peeled off.

[0017] _{W + 3H 2 O 2 → WO} 3 + 3H 2 O [ Formula _{1] WO 3 + 2NH 4 OH} → 2NH 4 + + WO 4 2- + H 2 O [ Equation _{2] Ti + H 2 O 2} + Y + 2NH 4 OH → 2NH 4 + + [TiO (H ₂ O ₂ ) Y] ²⁻ + H ₂ O [Formula 3] (In Formulas 2 and 3, Y represents ethylenediaminetetraacetic acid.)

As is clear from the above, in the method of the present invention, the conditions (pH range) for etching the TiW-based film on the semiconductor substrate are preferably in the alkaline region, and the specific pH range is preferred. For example, usually 7.2
-10, preferably 7.8-9.8, more preferably p
H8.2 to 9.2. Further, the pH of the solution according to the present invention used in the method of the present invention is also preferably in the above-mentioned pH range.

The solution according to the present invention can be prepared by mixing and dissolving hydrogen peroxide and the above-mentioned chelating agent, preferably a buffer, in water so as to have the above-mentioned concentrations. The components may be sequentially added to and mixed with water in an appropriate order, or may be dissolved in water after all the components have been added. The solution according to the present invention thus prepared is preferably subjected to a filtration treatment or the like before use. The water used here may be any water that has been purified by distillation, ion exchange treatment, or the like.

In the present invention, except for using hydrogen peroxide and the above-mentioned chelating agent, preferably a buffering agent, it is possible to use reagents commonly used in a known etching method.

Examples of such reagents include nonionic surfactants, anionic surfactants, and cationic surfactants used for the purpose of reducing the surface tension of a solution to improve the wettability to the semiconductor surface. And a surfactant such as an amphoteric surfactant. Among them, NCW1002
Nonionic surfactants such as (polyoxyethylene / polyoxypropylene alkyl ether, manufactured by Wako Pure Chemical Industries, Ltd.) are particularly preferred. These surfactants may be used in a concentration range usually used in this field, and the concentration in the solution according to the present invention is usually 0.001 to 1.0% by weight, preferably 0.01 to 0.5% by weight. % By weight.

As described above, the etching agent of the present invention contains hydrogen peroxide, a chelating agent, preferably a buffering agent, etc.
It is prepared by using it as a main component, and is supplied in various forms such as a one-part system or a two-part system such as a multi-part system.
When using the etching agent, in the case of a one-component system, it may be used as it is, and in the case of a multi-component system such as a two-component system, all the solutions are appropriately mixed before use. It goes without saying that a solution containing all the components as described above may be prepared and used.

Among them, a two-part or more multi-part system is preferred from the viewpoints of safety during transportation and storage, stability of the solution, and the like. Specifically, for example, (1) hydrogen peroxide A two-part system consisting of a solution containing a chelating agent, preferably a buffer, and (2) a solution containing a buffer is preferred. Preferred embodiments of each component in the two-part system as described above are as described above, and more specifically, for example, (1)
A solution comprising hydrogen peroxide, an alkane polyphosphonic acid which may have a hydroxy group, and ammonium borate, and a solution comprising (2) ammonia are particularly preferred. The concentration of each component used in the multi-part system as described above is the concentration in a solution containing all the components prepared by appropriately mixing all the solutions, that is, the final concentration is within the concentration range as described above. So that you can choose
It may be contained in each solution. That is, for example, in the case of a two-liquid system as described above, the final concentration when mixing the two liquids is usually 15 to 25% by weight, preferably 18 to 23% by weight, and the chelating agent is usually Is 0.01-6
% By weight, preferably 0.1 to 5% by weight, more preferably 1 to 3% by weight. When an ammonium salt of, for example, an inorganic acid is used as a buffer, the ammonium salt is usually 0.1% by weight.
01 to 10% by weight, preferably 0.05 to 6% by weight, more preferably 0.1 to 5% by weight. When, for example, ammonia is used as the buffer, the amount of ammonia is usually 0.01 to 20% by weight. , Preferably 0.05 to 12% by weight, more preferably 0.1 to 10% by weight,
What is necessary is just to prepare two solutions, respectively. More specifically, 2
As final concentrations when the liquids are mixed, hydrogen peroxide is usually 15 to 25% by weight, preferably 18 to 23% by weight, and the chelating agent is usually 0.01 to 6% by weight, preferably 0.1 to 0.2% by weight.
1 to 5% by weight, more preferably 1 to 3% by weight, ammonium salt of inorganic acid is usually 0.01 to 10% by weight, preferably 0.05 to 6% by weight, more preferably 0.1 to 5% by weight. %, So that hydrogen peroxide and a chelating agent, preferably a buffer, are contained in water, and the final concentration when the two solutions are mixed is usually 0.01 to 20% by weight of ammonia, preferably Each solution may be prepared by adding a buffer to water so as to be 0.05 to 12% by weight, more preferably 0.1 to 10% by weight.

Similarly, the pH of each solution in the multi-part system as described above is not particularly limited, and the pH of the solution containing all the components as described above, which is prepared by appropriately mixing all the solutions.
The pH of each solution may be adjusted so that H, that is, the final pH is in the pH range as described above. That is, for example, in the case of a two-liquid system as described above, the final p when mixing the two liquids is determined.
H is in an alkaline region, specifically, usually pH 7.2 to 1
0, preferably pH 7.8-9.8, more preferably p
What is necessary is just to adjust the pH of each solution so that it may become H8.2-9.2.

The method of the present invention uses a solution according to the present invention containing hydrogen peroxide and a chelating agent as described above, preferably a buffer, as an etching agent to form a solution on a semiconductor substrate.
Except for etching the i-type film, this may be performed according to a known etching method such as a dipping method or a spray etching method.

More specifically, for example, (1) a method in which a semiconductor substrate on which a Ti-based film is formed is immersed in an etching agent, and (2) a state in which a semiconductor substrate on which a Ti-based film is formed is immersed in an etching agent. (3) a method in which the solution is agitated by mechanical means, (3) a method in which the semiconductor substrate on which the Ti-based film is formed is immersed in an etchant, and the solution is vibrated with an ultrasonic wave or the like to agitate the solution; A method in which an etching agent is sprayed on the semiconductor substrate on which the Ti-based film is formed, or the like, may be used.
In the method of the present invention, when performing the etching as described above, the Ti-based film may be swung as necessary. In the method of the present invention, the etching method is not particularly limited, and for example, a batch method, a single-wafer method, or the like can be used.

[0027] The etching is completed in a shorter time when heated, as compared with normal temperature, but it is difficult to control the etching due to a decrease in pH. Therefore, it is preferable to set the temperature at the time of etching to 35 ° C. to 45 ° C.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0029]

EXAMPLES Example 1 (1) Preparation of etching agent An etching agent having the following composition was prepared. Hydrogen peroxide 20% by weight Ammonium borate 0.6% by weight Ammonia 2% by weight Chelating agent (NTPO: nitrilotrismethylphosphonic acid) 2% by weight Water 75.4% by weight pH 9.0

(2) Etching The etching agent obtained in the above (1) is put into a general-purpose wet booth, and the liquid temperature is adjusted to 4 by a liquid circulation type temperature controller.
The temperature was set at 0 ° C. and the circulation flow rate was 28 L / min. The etching of the substrate to be etched on which the TiW film was formed was performed by a dipping method using the above-mentioned etching agent. In this etching, a substrate to be etched on which a 500 nm-thick TiW film was formed, and a 1.8 μm-thick positive resist were used as a mask.

(3) Results The results are shown in FIG. In FIG. 2, each numeral indicates the following. 21: Positive resist 22: Al 23: TiW film 24: underlying oxide film 25: TiW etching residue

Comparative Example 1 (1) Etching The substrate to be etched on which a TiW film was formed was etched by RIE. As in Example 1, a substrate to be etched on which a 500 nm-thick TiW film was formed, and a 1.8 μm-thick positive resist were used as a mask.

(2) Results The results are shown in FIG.

As is apparent from the results shown in FIG. 2, etching residues are generated in the conventional RIE method (Comparative Example 1), whereas etching residues are generated in the method of the present invention (Example 1). It can be seen that no etching was performed and that etching could be performed well. In addition, it can be seen that excessive side etching did not occur, and further, the etching selectivity with respect to the resist and the underlying film was improved, so that the process margin was increased.

Example 2 (1) Preparation of etching agent An etching agent having the following composition was prepared. a) Liquid 1 22% by weight of hydrogen peroxide 4.8% by weight of ammonium borate Chelating agent (HEDPO: 1-hydroxyethylidene-1,1'-diphosphonic acid) 2.2% by weight Water 71% by weight pH 3.5 b) Second liquid ammonia 14% by weight water 86% by weight pH12

(2) Etching 900 ml of the first liquid and 100 ml of the second liquid obtained in the above (1)
The substrate to be etched on which the TiW film was formed was etched in the same manner as in Example 1 except that a mixture of the above (final pH 8.2) was used as an etching agent.

(3) Results As in the case of the first embodiment, no etching residue is generated in the method of the second embodiment, and the etching selectivity with respect to the resist and the underlying film is improved, so that the process margin is increased. Was.

[0038]

As described above, the present invention provides a method of etching a Ti-based film without generating an etching residue and a method of etching a Ti-based film.
The present invention provides an etching agent used for etching a base film. By using the present invention, there is an effect that the Ti-based film can be etched at a low cost with a large process margin without having to use an expensive apparatus, having an excellent etching effect as compared with the conventional method.

[0039]

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between etching time and pH.

FIG. 2 is a schematic diagram showing the result of etching by the method of the present invention obtained in Example 1 and the result of etching by the conventional method obtained in Comparative Example 1, respectively.

[Explanation of symbols]

 In FIG. 2, each numeral indicates the following. 21: Positive resist 22: Al 23: TiW film 24: underlying oxide film 25: TiW etching residue

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mayumi Kimura 1633 Ojiba Kawagoe-shi, Saitama Wako Pure Chemical Industries, Ltd. Tokyo Research Laboratory F-term (reference) 4K057 WA01 WA02 WA13 WB08 WB17 WE01 WE04 WE11 WE23 WE25 WG03 WG06 WN01 WN02 5F043 AA26 AA27 BB15 GG02 GG04

Claims (29)

[Claims] 1. An etching method comprising etching a Ti-based film on a semiconductor substrate using a solution containing hydrogen peroxide and a chelating agent. 2. A chelating agent comprising: (1) a nitrogen-containing polycarboxylic acid having from 1 to 4 nitrogen atoms and from 2 to 6 carboxyl groups in a molecule; (2) from 1 to 3 nitrogen atoms in a molecule; Atom and two
Nitrogen-containing polyphosphonic acids having up to 5 phosphonic acid groups, (3) alkane polyphosphonic acids optionally having a hydroxy group, (4) N-substituted amino acids, (5) amides,
(6) alkylenediamines, (7) polyalkanolamines, (8) aromatic diamines, (9) polyalkylenepolyamines, (10) condensed phosphoric acids, (11) alkanoyl ketones,
And (12) the etching method according to claim 1, wherein the etching method is selected from the group consisting of inorganic ions having a complex forming ability. 3. The etching method according to claim 2, wherein the chelating agent is an alkane polyphosphonic acid which may have a hydroxy group. 4. An alkane polyphosphonic acid which may have a hydroxy group is 1-hydroxyethylidene-1,1′-
The etching method according to claim 3, wherein the etching method is diphosphonic acid, 1-hydroxypropylidene-1,1'-diphosphonic acid, or 1-hydroxybutylidene-1,1'-diphosphonic acid. 5. The etching method according to claim 1, wherein the solution further contains a buffer. 6. The etching method according to claim 5, wherein the buffer is an ammonium salt of ammonia and / or an inorganic acid, or ammonia and an inorganic acid or an alkali metal salt thereof. 7. The etching method according to claim 6, wherein the buffer is ammonia and an inorganic acid or an ammonium salt of ammonia and an inorganic acid. 8. The etching method according to claim 6, wherein the inorganic acid is boric acid. 9. The method according to claim 1, wherein the solution is an alkaline solution.
9. The etching method according to any one of the above items 8. 10. The etching method according to claim 1, wherein the solution has a pH of 7.2 to 10. 11. An etching agent for a Ti-based film on a semiconductor substrate, comprising a solution containing hydrogen peroxide and a chelating agent. 12. A chelating agent comprising: (1) a nitrogen-containing polycarboxylic acid having 1 to 4 nitrogen atoms and 2 to 6 carboxyl groups in the molecule, and (2) 1 to 3 nitrogen atoms in the molecule. Nitrogen-containing polyphosphonic acids having an atom and 2 to 5 phosphonic acid groups, (3) alkane polyphosphonic acids optionally having a hydroxy group, (4) N-substituted amino acids, (5) amides,
(6) alkylenediamines, (7) polyalkanolamines, (8) aromatic diamines, (9) polyalkylenepolyamines, (10) condensed phosphoric acids, (11) alkanoyl ketones,
12. The etching agent according to claim 11, wherein the etching agent is selected from the group consisting of (12) an inorganic ion having a complex forming ability. 13. The method according to claim 1, wherein the chelating agent is an alkane polyphosphonic acid optionally having a hydroxy group.
3. The etching agent according to 2. 14. An alkane polyphosphonic acid which may have a hydroxy group is 1-hydroxyethylidene-1,
14. The etching agent according to claim 13, which is 1'-diphosphonic acid, 1-hydroxypropylidene-1,1'-diphosphonic acid, or 1-hydroxybutylidene-1,1'-diphosphonic acid. 15. The etching agent according to claim 11, wherein the solution further contains a buffer. 16. The etching agent according to claim 15, wherein the buffer is an ammonium salt of ammonia and / or an inorganic acid, or ammonia and an inorganic acid or an alkali metal salt thereof. 17. The etching agent according to claim 16, wherein the buffering agent is ammonia and an inorganic acid, or an ammonium salt of ammonia and an inorganic acid. 18. The etching agent according to claim 17, wherein the solution comprises hydrogen peroxide, nitrogen-containing polyphosphonic acids, ammonia and an ammonium salt of an inorganic acid. 19. The method of claim 1, wherein the inorganic acid is boric acid.
An etching agent according to any one of 6 to 18. 20. 15 to 25% by weight of hydrogen peroxide, 0.01 to 6% by weight of nitrogen-containing polyphosphonic acids, 0.1% of ammonia.
0.01-20% by weight, and ammonium borate 0.01-
20. The etchant according to claim 19, comprising 10% by weight. 21. The etching agent according to claim 11, wherein the pH of the solution is 7.2 to 10. 22. The etching agent according to claim 22, further comprising a solution containing a buffer. 23. The etching agent according to claim 22, wherein the buffering agent is ammonium or an ammonium salt of an inorganic acid or ammonia and an inorganic acid or an alkali metal salt thereof. 24. The etching agent according to claim 23, wherein the buffering agent is ammonia and an inorganic acid, or an ammonium salt of ammonia and an inorganic acid. 25. The solution comprising hydrogen peroxide, an alkane polyphosphonic acid optionally having a hydroxy group, ammonia and an ammonium salt of an inorganic acid.
An etching agent according to claim 22. 26. The method of claim 2, wherein the inorganic acid is boric acid.
The etching agent according to any one of 3 to 25. 27. The pH of a solution containing hydrogen peroxide and a chelating agent and the pH of a solution containing a buffer are adjusted so that the final pH when these solutions are mixed is in the range of 7.2 to 10. The etching agent according to any one of claims 22 to 26, which is adjusted respectively. 28. A solution comprising hydrogen peroxide, an alkane polyphosphonic acid which may have a hydroxy group, and ammonium borate, and a solution comprising ammonia. And 15 to 25% by weight of hydrogen peroxide, 0.01 to 6% by weight of alkane polyphosphonic acids optionally having a hydroxy group, 0.01 to 20% by weight of ammonia, and boric acid as final concentrations. An etching agent for a Ti-based film used as an etching agent containing 0.01 to 10% by weight of ammonium. 29. The pH of a solution containing hydrogen peroxide, an alkane polyphosphonic acid optionally having a hydroxy group, and ammonium borate, and the pH of a solution containing ammonia, and these solutions are mixed. Final pH when done
29. The etching agent according to claim 28, wherein each of them is adjusted so as to fall within a range of 7.2 to 10.