KR20210153221A - Selective Etching Method - Google Patents

Abstract

A metal selected from among titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum, and gallium formed over an underlying substrate, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride or an alloy layer of the silicon nitride, hafnium nitride, and tantalum nitride are selectively etched using an alkaline etching solution containing a predetermined complexing agent preferentially over the underlying substrate selected from glass, silicon, copper, and nickel.

Description

Selective Etching Method

The present invention relates to a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium formed on the substrate preferentially over an underlying substrate selected from glass, silicon, copper and nickel, It relates to a method of selectively etching an oxide, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy layer thereof.

In general, when etching titanium, a hydrofluoric acid-based etching solution is used. However, when a hydrofluoric acid-based etching solution is used, when the underlying layer is nickel or glass, the underlying layer is also etched.

In the case of etching titanium, it can also be considered to use a sodium hydroxide solution, but titanium is hardly etched by this etching solution alone, and even if hydrogen peroxide is used in combination to improve the etching rate, the etching rate is too slow and practical is not

In recent years, as an etching solution for titanium, a method using EDTA as a complexing agent is known, and specifically, a method containing EDTA and hydrogen peroxide and using an alkaline etching solution is known (Patent Document 1). In this method, titanium deposited on lithium niobate (LiNbO3) can be selectively etched, but there is a problem in that the etching rate is slow. In addition, in this method, there was a material (metal) that could not be etched, or the underlying substrate was affected depending on the type of the substrate. For example, because the etching rate of titanium is slower than that of nickel, the underlying material is dissolved first.

As a result of intensive research to solve the above problems, the present inventors have found that, as a result of intensive research, an alkaline etching solution containing a specific complexing agent is preferentially selected from the group consisting of glass, silicon, copper and nickel, titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, It has been found that a metal selected from arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy thereof can be selectively etched, and the present invention has been accomplished.

That is, the present invention relates to a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, and a nitride of the metal provided on a base substrate selected from glass, silicon, copper and nickel , silicon nitride, hafnium nitride, tantalum nitride or an alloy layer thereof, the following formulas (I) and (II),

[In formula (I), R1 to R3 are the same as or different from each other and are -Ra, -ORb, -OORc, -COORd, -COOORe, -CH2COORf, -CH2COOORg, -CRhO or -CH2CHCH3 (Ra to Rhh

are the same as or different from each other and are hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, an unsaturated aliphatic group having 1 to 10 carbon atoms, or an aryl group)]

[In formula (11), R4 to R7 are the same as or different from each other, and -Ri, -Rj, -OORk, -COORl, -COOORm, -CH2COORn, -CH2COOORo, -CRpO, -CH2CHCH3, -CN, -NC -NO2, -F, -Cl, -Br, -I, -S02Rq; or an aryl group), X is —OH, —COOH or —COOOH]

A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, which essentially contains at least one complexing agent selected from compounds represented by It is an etching method characterized in that the oxide of the metal, the nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy thereof is selectively etched.

In addition, the present invention is a formula (I) and (II),

[In formula (I), R1 to R3 are the same as or different from each other and are -Ra, -ORb, -OORc, -COORd, -COOORe, -CH2COORf, -CH2COOORg, -CRhO or -CH2CHCH3 (Ra to Rhh

are the same as or different from each other, hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, carbon

an unsaturated aliphatic group having a number of 1 to 10 or an aryl group)]

[In formula (II), R4 to R7 are the same as or different from each other, and -Ri, -Rj, -OORk, -COORl, -COOORm, -CH2COORn, -CH2COOORo, -CRpO, -CH2CHCH3, -CN, -NC, -NO2, -F, -Cl, -Br, -I, -S02Rq; or an aryl group), X is —OH, —COOH or —COOOH]

Titanium, niobium, tungsten, molybdenum, ruthenium, rhodium provided on an underlying substrate selected from glass, silicon, copper and nickel, which essentially contains at least one complexing agent selected from the compounds represented by , arsenic, a metal selected from aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an etchant for alloys thereof.

The present invention provides, at a practical rate, and in preference to an underlying substrate selected from glass, silicon, copper and nickel, a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, said metal It is possible to selectively etch oxides, nitrides of the above metals, silicon nitride, hafnium nitride, tantalum nitride, or alloys thereof.

In addition to the above etching, the present invention relates to the reuse of an underlying substrate selected from glass, silicon, copper and nickel, the above metal, an oxide of the above metal, a nitride of the above metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy thereof. It can also be used for the recovery of

BRIEF DESCRIPTION OF THE DRAWINGS In Test Example 1, it is a photograph of the external appearance of the sample after etching using the etching liquid of Example 6 under the etching conditions of 80 degreeC and 30 second.
2 is an SPM photograph and Ra value of a sample in Test Example 4 after etching using the etching solution of Example 6 under etching conditions at 80° C. for 5 minutes (in the figure, (A) is the surface of Sample A, and FIG. , (B) is the surface of sample B, (C) is the surface after etching of sample B, (D) is the surface after etching of sample A)
3 is an SEM photograph (top) and an SPM photograph (bottom) of a sample in Test Example 5 after etching using the etching solution of Example 6 under quenching conditions of 80° C. and 40 minutes (in the figure, (A)) is the surface of sample A, (B) is the surface of sample B, (C) is the surface of sample B after etching)
4 is an SEM photograph (top) and an SPM photograph (bottom) of a sample after etching using the etching solution of Example 6 under etching conditions of 80° C. and 25 seconds in Test Example 6 (in the figure, (A) is The surface of sample A, (B) is the surface of sample B, (C) is the surface of sample B after etching)

A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium of the present invention, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride or an alloy thereof The etching method (hereinafter simply referred to as the "method of the present invention") is selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium formed on an underlying substrate selected from glass, silicon, copper and nickel. A metal, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy layer thereof, the following formulas (I) and (II),

It is carried out by essentially containing at least one complexing agent selected from the compounds represented by and contacting it with an alkaline etching solution. In addition, in this specification, "consisting essentially of" is a substance other than the substance described as essentially containing, and does not contain substances that seem to affect the effect (in other words, it does not affect the effect). It means that it preferably contains no substances other than substances described as essentially containing (in other words, only substances described as containing essentially are included). do.

Among the complexing agents used in the method of the present invention, R1 to R3 of the compound represented by formula (I) are the same as or different from each other, and -Ra, -ORb, -OORc, -COORd, -COOORe, -CH2COORf, -CH2COOORg , -CRhO or -CH2CHCH3 (Ra to Rh are the same as or different from each other and are hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, an unsaturated aliphatic group having 1 to 10 carbon atoms, or an aryl group), preferably -H , -OH -COOH or -CH2COOH.

Specific examples of the compound represented by the formula (I) include 3-hydroxypropionic acid, tartaric acid, citric acid, malic acid, malonic acid, galacturonic acid, galactaric acid, gluconic acid, hydroxybutyric acid, 2,2-bis(hydroxy methyl) butyric acid, hydroxypivaric acid, hydroxyisovaleric acid, and the like, and among these, tartaric acid and citric acid are preferable. Further, the compound represented by the formula (I) includes those in the form of alkali metal salts or ammonium salts such as lithium salt, sodium salt, potassium salt and the like, and exhibiting the same behavior as the compound in the etching solution.

In addition, among the complexing agents used in the method of the present invention, R of the compound represented by the formula (II)

4 to R7 are the same as or different from each other, -Ri, -0Rj, -0ORk, -COORl, -COOORm, -CH2COORn, -CH2COOORo, -CRpO, -CH2CHCH3, -CN, -NC, -NO2, -F,

-Cl, -Br, -I, -S02Rq (Ri to Rq may be the same or different from each other, and are hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, an unsaturated aliphatic group having 1 to 10 carbon atoms, or an aryl group. ), preferably -H, -COOH, -CH2COOH.

Moreover, X of the compound represented by Formula (II) is -OH, -COOH, or -COOOH, Preferably it is -OH or -COOH.

Specific examples of the compound represented by formula (II) include protocatechuic acid, ethyl protocasechuate, salicylic acid, 2,3-dihydroxybenzoic acid, 5-chlorosalicylic acid, cresotinic acid , resorcylic acid, naphthoic acid, 3,5-dihydroxy2-naphthoic acid, 1,4-dihydroxy-2-naphthoic acid, 1-hydroxy-2-na

Phthophosphoric acid, 2,6-hydroxy-4-methylbenzoic acid, 2,5-dihydroxyterephthalic acid, methylenedisalicylic acid, nitrosalicylic acid, 2,4,6-trihydroxybenzoic acid, 5-sulfosalicylic acid, Modant Blue 1 (Mordant blue 1), chrome yellow, 4-tert-butylcatechol, 4-methylcatechol, catechol, bromocatechol, chlorocatechol, iodocatechol, fluorocatechol, nitrocatechol, cyano and catechol, alizarin, esculetin, gallic acid, ethyl gallate, and 3,4-dihydroxybenzoyl aldehyde. Among them, protocatechuic acid or salicylic acid is preferable. do. Moreover, as a compound represented by Formula (II), it is the form of alkali metal salts, such as a lithium salt, a sodium salt, and a potassium salt, and an ammonium salt, and the thing which behaves similarly to the said compound in etching liquid is also contained.

The content of the complexing agent in the etching solution is 0001 mol/L or more, preferably 01 to 1 mol/L.

The liquidity of the etching solution used in the method of the present invention is not particularly limited as long as it is alkaline, but the higher the pH of the etching solution, the higher the etching rate. pH 11-14, More preferably, it is set as pH 12-14. The method of making an etching liquid alkaline is not specifically limited, What is necessary is just to use alkaline substances, such as sodium hydroxide and potassium hydroxide.

It is preferable to further contain an oxidizing agent in the etching liquid used by the method of this invention. By containing this oxidizing agent in an etching liquid, an etching rate improves. The type of the oxidizing agent is not particularly limited, but it is preferable that the oxidizing agent itself does not corrode the underlying substrate. Examples of the oxidizing agent that does not corrode the underlying substrate include percarboxylic acids such as oxygen, hydrogen peroxide, ozone, peracetic acid, and perbenzoic acid. Among these oxidizing agents, oxygen, hydrogen peroxide that does not generate by-products, Ozone is preferred. The content of the oxidizing agent in the etching solution is 0001 to 10 mass% (hereinafter, simply referred to as “%”), preferably 01 to 3%. In the case where the oxidizing agent is a gas such as oxygen or ozone, the gas may be introduced by bubbling or the like so that the concentration in the etching solution is within the above range.

Moreover, to the etching liquid used by the method of this invention, you may add surfactant normally used for etching liquid in the range which does not impair the effect of this invention. By adding a surfactant, the uniformity of etching is improved. As a preferable surfactant, liquid polyethylene glycol, such as PEG-200, is mentioned.

As a preferable example of the etching liquid used by the method of this invention, the thing containing the said complexing agent essentially and being alkaline is mentioned.

Moreover, as another preferable example of the etching liquid used by the method of this invention, the thing containing the said complexing agent and an oxidizing agent essentially and being alkaline is mentioned.

Moreover, as another preferable example of the etching liquid used by the method of this invention, the thing containing the said complexing agent, an oxidizing agent, and surfactant essentially, and being alkaline is mentioned.

Preferred compositions of the etching solution used in the method of the present invention include salicylic acid or its alkali metal salt or ammonium salt 01 to 04 mol/L and/or tartaric acid or its alkali metal salt or ammonium salt 01 to 04 mol/L and/or citric acid or its alkali 01 to 04 mol/L of a metal salt or ammonium salt, and 03 to 3% of hydrogen peroxide, and containing a pH of 11 or more, preferably a pH of 12 to 14, more preferably a pH of 13 to 14. As a composition, 01-04 mol/L of sodium salicylate, 01-04 mol/L of sodium potassium tartrate (Roxhel salt), 01-04 mol/L of trisodium citrate, 01-04 mol/L of sodium hydroxide, and 03-3% of hydrogen peroxide those containing

A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or these metals to be etched by the method of the present invention Specific examples of the alloy of titanium, titanium (II) oxide, titanium (III) oxide, titanium (IV) oxide, titanium nitride,

Niobium, Niobium (II) Oxide, Niobium (III) Oxide, Niobium (IV) Oxide, Niobium (V) Oxide, Niobium Nitride, Tungsten, Molybdenum, Ruthenium, Rhodium, Arsenic, Aluminum, Aluminum Oxide, Aluminum Nitride, Gallium Oxide and alloys such as gallium, gallium nitride, silicon nitride, hafnium nitride, tantalum nitride, and niobium titanium and gallium arsenide in which one or more of these are combined. Among these, titanium, titanium (II) oxide, titanium (III) oxide, titanium (IV) oxide, titanium nitride, niobium, niobium (II) oxide, niobium (III) oxide, niobium (IV) oxide, niobium (V) oxide , niobium nitride, tantalum nitride, silicon nitride, aluminum, aluminum oxide, aluminum nitride, gallium, gallium oxide, gallium nitride, and aluminum nitride/aluminum alloy are preferable.

Among the base substrates used in the method of the present invention, silicate glass, quartz, Pyrex, TEMPAX, soda lime glass, borosilicate glass, etc. are mentioned as glass. Silicon, arsenic-doped silicon, antimony-added silicon, polycrystalline silicon, etc. are mentioned, As copper, pure copper metal, a copper-containing alloy, etc. are mentioned, As nickel, pure nickel metal, a nickel containing alloy, etc. are mentioned. Further, as the underlying substrate, a metal selected from the group consisting of titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, and tantalum nitride to be etched Or those containing alloys thereof are excluded. Moreover, the shape of the said base material is not specifically limited, Any of plate shape, annular shape, spherical shape, these combinations, etc. may be sufficient.

In addition, a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy layer thereof on the underlying substrate There is no particular limitation on the method of forming the layer, and it may be formed by generally performed sputtering, vapor deposition, plating, or the like.

A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy layer of these metals formed on the underlying substrate , The method of contacting the etching solution is not particularly limited, for example, a method of immersing the underlying substrate having the layer formed thereon in the etching solution, a method of spraying the etching solution on the layer, a method of applying the etching solution to the layer, etc. can be heard

In addition, the etching conditions in the method of the present invention are not particularly limited, but for example, the liquid temperature of the etching solution is 20 to 100°C, preferably 40 to 80°C, and the processing time is 01 to 200 minutes; Preferably, it is 1 to 20 minutes. In addition, in the method of the present invention, the etching rate is the concentration of the compound represented by the formulas (I) and (II) contained in the etching solution, the pH of the etching solution, to

A person skilled in the art can appropriately control the temperature and treatment time of the liquid of the quenching liquid.

Furthermore, in the method of the present invention, it is preferable to stir the etching solution by means of a stirrer, bubbling, or the like at the time of etching. By stirring, the uniformity of etching is improved, or re-adhesion to an underlying substrate such as the etched metal does not occur.

The method of the present invention described above can include a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal from the underlying substrate selected from glass, silicon, copper and nickel, The nitride, silicon nitride, hafnium nitride, tantalum nitride, or alloy layer of the above metal is preferentially applied to the underlying substrate

, so it can be selectively removed.

Preferred examples of a combination of a metal that can be selectively removed by the method of the present invention and the underlying substrate include the following.

(substrate) (metal, etc.)

free titanium and/or niobium and/or respective oxides and/or nitrides nickel titanium and/or titanium oxide and/or titanium nitride and/or silicon nitride tantalum nitride and/or titanium and/or titanium nitride and/or titanium oxide and/or aluminum and/or aluminum oxide and/or aluminum nitride and/or gallium and/or potassium oxide and/or

Copper Gallium Nitride Aluminum and/or Aluminum Nitride and/or Gallium and/or Gallium Nitride

Example

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples at all.

Example 1

Etching solution:

In 100 ml of water, 154 g of protocatechuic acid and 12 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Example 2

Etching solution:

In 100 ml of water, 192 g of citric acid and 12 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Example 3

Etching solution:

In 100 ml of water, 138 g of salicylic acid, 1 ml of hydrogen peroxide (30%) and 08 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Example 4

Etching solution:

In 100 ml of water, 150 g of tartaric acid, 1 ml of hydrogen peroxide (30%) and 12 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Example 5

Etching solution:

In 100 ml of water, 192 g of citric acid, 1 ml of hydrogen peroxide (30%) and 169 sodium hydroxide were dissolved. The pH of this etchant was 14.

Example 6

Etching solution:

In 300 ml of water, 138 g of salicylic acid, 150 g of tartaric acid, 192 g of citric acid, 3 ml of hydrogen peroxide (30%) and 36 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Comparative Example 1

Etching solution:

In 100 ml of water, 1 ml of hydrogen peroxide (30%) and 12 g of sodium hydroxide were dissolved. The pH of this etchant was 14.

Comparative Example 2

Etching solution:

In 100 ml of water, 416 g of EDTA·4Na, 1 ml of hydrogen peroxide (30%) and 04 g of sodium hydroxide were dissolved. The pH of this etching solution was 14.

Comparative Example 3

Etching solution:

In 100 ml of water, 138 g of salicylic acid, 1 ml of hydrogen peroxide (30%) and 04 g of sodium hydroxide were dissolved. The pH of this etching solution was 5.

Comparative Example 4

Etching solution:

14 g of ethyl maltol and 08 g of sodium hydroxide were dissolved in 100 ml of water. The pH of this etchant was 14.

Comparative Example 5

Etching solution:

10 g of acetyl acetone and 08 g of sodium hydroxide were dissolved in 100 ml of water. The pH of this etchant was 14.

Comparative Example 6

Etching solution:

06 g of glycol and 08 g of sodium hydroxide were dissolved in 100 ml of water. The pH of this etchant was 14.

Comparative Example 7

Etching solution:

176 g of ascorbic acid, 1 ml of hydrogen peroxide (30%), and 12 g of sodium hydroxide were dissolved in 100 ml of water. The pH of this etching solution was 14.

Comparative Example 8

Etching solution:

154 g of protocasechuic acid was dissolved in 100 ml of water. The pH of this etchant was 5.

Test Example 1

Etching Test:

A sample in which titanium was deposited to a thickness of 100 nm by sputtering on the inner surface of a glass cylinder was used as a sample. While the etching solution prepared in Examples 1-6 and Comparative Examples 1-8 was stirred with a stirrer, the sample was immersed in this under the conditions shown in Table 1, and the etching test was done. The appearance of the sample after the etching test was evaluated according to the following evaluation criteria. These results are also shown in Table 1. Moreover, the photograph of the external appearance of the sample after etching using the etching liquid of Example 6 under the etching conditions of 80 degreeC and 30 second was shown in FIG.

<Titanium dissolution evaluation criteria>

(Evaluation) (Content)

(double-circle): Titanium melt|dissolved completely.

(circle): Titanium melt|dissolved substantially.

(triangle|delta): Titanium hardly melt|dissolved.

x: Titanium did not melt|dissolve at all.

<Evaluation criteria for melting glass>

(Evaluation) (Content)

+: Glass did not melt|dissolve.

-: Glass melt|dissolved.

From the above results, when hydrogen peroxide is not added to the etching solution of the present invention only as a complexing agent, protocasechu phosphoric acid is the best. Moreover, when a complexing agent and hydrogen peroxide were combined, an etching rate improved and it turned out that it becomes faster than the case where EDTA is used. Moreover, it has been found that etching requires a high pH. Furthermore, among the 1,2-diols, in general, etching was not performed at all or was hardly performed, but it was found that the 1,2-benzenediols contained in the formula (II) were effective. Furthermore, it was found that etching was not performed at all in β-diketones and α-hydroxyketones of general titanium complexing agents. In addition, it was found that etching was not performed at all with a complexing agent having a reducing power.

Test Example 2

Etching Test:

On both sides of the hairline-processed brass ring, nickel-plated, 10 nm titanium oxide, 70 nm titanium, 45 nm silicon nitride, 85 nm titanium nitride, 80 nm silicon nitride, and 10 nm titanium nitride by sputtering in this order What was vapor-deposited was used as a sample. While stirring the etching solution prepared in Examples 1 and 3 to 6 and Comparative Examples 1 to 3 and 6 to 8 with a stirrer, the sample was immersed in this under the conditions shown in Table 2, and an etching test was performed. The following evaluation criteria evaluated the external appearance of the sample after an etching test. These results are also shown in Table 2. Moreover, about the sample after etching under the etching conditions of 80 degreeC and 5 minutes using the etching liquid of Example 6, it analyzed with the electron beam microanalyzer (EPMA).

<Evaluation criteria for dissolution of titanium oxide, titanium, silicon nitride, and titanium nitride>

(Evaluation) (Content)

(double-circle): Titanium oxide, titanium, silicon nitride, and titanium nitride melt|dissolved completely.

(circle): Titanium oxide, titanium silicon nitride, and titanium nitride were substantially melt|dissolved.

(triangle|delta): Titanium oxide, titanium, silicon nitride, and titanium nitride hardly melt|dissolved.

x: Titanium oxide, titanium, silicon nitride, and titanium nitride did not melt|dissolve completely.

<Evaluation criteria for dissolution of nickel>

(Evaluation) (Content)

+: Nickel did not melt|dissolve.

- : Nickel melted.

From the above results, since the etching solution of the present invention dissolves titanium oxide, titanium, silicon nitride, and titanium nitride preferentially than the underlying nickel, it was found that these can be selectively removed from the underlying nickel. Further, as a result of analysis by EPMA, before and after etching, nickel from 640 mol% to 742 mol%, copper from 60 mol% to 164 mol%, zinc from 34 mol% to 94 mol%, and titanium from 116 mol% to O mol% , found that both titanium and silicon were removed by etching from 150 mol% to O mol% of silicon.

Test Example 3

Etching Test:

A sample obtained by depositing 50 µm of tantalum nitride on one surface of a silicon wafer by sputtering was used. While the etching solution prepared in Examples 1, 3-6 and Comparative Examples 1-3 was stirred with a stirrer, the sample was immersed in this under the conditions shown in Table 3, and the etching test was implemented. The following evaluation criteria evaluated the external appearance of the sample after an etching test. These results are also shown in Table 3.

<Evaluation criteria for dissolution of tantalum nitride>

(Evaluation) (Content)

(double-circle): Tantalum nitride melt|dissolved completely.

(circle): Tantalum nitride melt|dissolved substantially.

(triangle|delta): tantalum nitride hardly melt|dissolved.

x: tantalum nitride did not melt|dissolve completely.

<Evaluation criteria for dissolution of silicon>

(Evaluation) (Content)

+: Silicon did not melt|dissolve.

- : Silicon melted

From the above results, it was found that the etching solution of the present invention dissolves tantalum nitride preferentially than the underlying silicon, and thus can selectively remove them from the underlying silicon.

Test Example 4

Etching Test:

Sample A was nickel-plated on one side of a brass plate, and 10 nm titanium oxide, 70 nm titanium, 45 nm silicon nitride, 85 nm titanium nitride, 80 nm silicon nitride, and 10 nm titanium nitride were applied to this by sputtering. What was vapor-deposited in this order was made into sample B. Sample A and Sample B, while stirring the etching solution prepared in Example 6 with a stirrer, 80 ° C., 5 minutes

It was immersed under the conditions of, and an etching test was performed. The surface shape and surface roughness (Ra value) were observed by the scanning probe microscope (SPM) about the sample before and behind an etching test. The results are shown in FIG. 2 .

From the results of SPM observation and Ra measurement, it was found that since the etching solution of the present invention dissolves titanium oxide, titanium, silicon nitride, and titanium nitride preferentially than the underlying nickel, they can be selectively removed from the underlying nickel.

Test Example 5

Etching Test:

Sample B was obtained by depositing 50 µm of tantalum nitride on one side of a silicon wafer (Sample A) by sputtering. The sample B was immersed on the conditions of 80 degreeC and 40 minutes, stirring the etching liquid prepared in Example 6 with a stirrer, and what carried out the etching test was made into the sample C. These samples were observed with a scanning electron microscope (SEM) and SPM. The results are shown in FIG. 3 .

From the results of the SEM observation and SPM observation, it was found that the etching solution of the present invention dissolves tantalum nitride preferentially than the underlying silicon, and therefore it is possible to selectively remove them from the underlying silicon.

Test Example 6

Etching Test:

Sample B was obtained by depositing titanium nitride and titanium oxide by sputtering on one side of a silicon wafer (sample A), each 50 µm in this order. The sample B was immersed in 80 degreeC and conditions for 25 second, stirring the etching liquid prepared in Example 6 with a stirrer, and what carried out the etching test was made into the sample C. These samples were observed by SEM and SPM. The results are shown in FIG. 4 .

From the results of SEM observation and SPM observation, it was found that the etching solution of the present invention dissolves titanium nitride and titanium oxide preferentially rather than underlying silicon, and thus can selectively remove them from underlying silicon.

Test Example 7

Selection of etching conditions:

The etching solution contains 0334 mol/L of salicylic acid, 0333 mol/L of tartaric acid, 0333 mol/L of citric acid and 1 mol/L of hydrogen peroxide, the pH of which is adjusted to 11 or more with sodium hydroxide. As described in 4, the etching liquid was diluted. While stirring these etching solutions with a stirrer, the conditions shown in Table 4 using this

The same sample (glass cylinder) as used in Test Example 1 and the same sample (ring) as used in Test Example 2 were etched with this method.

In addition, the etching end time is the time until the sputtering film is removed by visual observation.

-: untested

From the above results, the relationship between the concentration of the complexing agent and the bath temperature with respect to the etching rate was confirmed. It was found that the etching rate increased as the concentration of the complexing agent and the bath temperature increased.

Test Example 8

Elemental analysis of etching solution after use:

Using the etching solution of Example 6, the same sample (glass cylinder) used in Test Example 1 was used at 80°C for 30 seconds, the same sample (ring) used in Test Example 2 was used at 80°C for 5 minutes, in Test Example 6 ICP-AES elemental analysis was performed on the same sample as used (titanium nitride and titanium oxide deposited on a silicon wafer (Sample B)) after etching at 80° C. for 25 seconds.

did Moreover, elemental analysis was performed also about the etching liquid after etching the same sample using the etching liquid of Comparative Example 2 as a comparison. Table 5 shows the results of these analyzes.

From the above results, it turned out that titanium melt|dissolves preferentially over nickel and silicon|silicone compared with the conventional thing in the etching liquid of this invention. In the etching solution of the present invention, 361 mg/L of silicon and nickel were not detected with respect to titanium at 5 mg/L.

On the other hand, in the conventional one, silicon was 235 mg/L and nickel was 85 mg/L, while titanium was 1 mg/L. Compared with the amount of titanium in the conventional one, it is considered that excess silicon is dissolved from a silicon wafer substrate and nickel is a nickel plated substrate. It was found that the complexing agent used in the present invention exhibits selectivity for dissolution of titanium and nitride.

Test Example 9

Determination of Etching Rate:

(1) Measurement of the etching rate of titanium

The etching rate of titanium is that 100 nm of titanium is deposited by sputtering on glass, and the etching solution shown in Table 6 is immersed in a thing at 80° C. while stirring with a stirrer, etching time, amount of dissolved titanium, area contacted with the etching solution was calculated from The results are shown in Table 6.

(2) Measurement of etching rate of titanium oxide/titanium nitride

The etching rate of titanium oxide/titanium nitride is that titanium oxide and titanium nitride are deposited by sputtering on a silicon wafer by 50 nm each in this order, and the etching solution shown in Table 7 is immersed at 80°C while stirring with a stirrer. and calculated from the etching time, the amount of dissolved titanium oxide/titanium nitride, and the contact area to the etching solution. The results are shown in Table 7.

(3) Measurement of the etching rate of niobium

As for the etching rate of niobium, 200 nm of niobium is vapor-deposited by sputtering on glass, and the etching solution shown in Table 8 is immersed in a thing at 80 ° C. while stirring with a stirrer, etching time, amount of dissolved niobium, contact with etching solution It was calculated from the area. The results are shown in Table 8.

(4) Measurement of etching rate of tantalum nitride

The etching rate of tantalum nitride was determined by depositing 50 nm of tantalum nitride on a silicon wafer by sputtering, immersing the etching solution shown in Table 9 at 80 ° C. while stirring with a stirrer, etching time, amount of dissolved tantalum nitride, etching solution It computed from the contact area to. The results are shown in Table 9.

Test Example 10

Determination of Etching Rate:

(1) Measurement of the etching rate of glass

The etching rate of the glass was calculated from the difference in weight before and after etching with respect to the etching time, the amount of dissolved glass, and the contact area of the plate glass to the etching solution by immersing the etching solution in Table 10 at 80° C. while stirring it with a stirrer. The results are shown in Table 10.

(2) Measurement of the etching rate of silicon

The etching rate of silicon is calculated from the difference in weight before and after etching with respect to the etching time, the amount of dissolved silicon, and the contact area of the silicon wafer with the etching solution by immersing the etching solution shown in Table 11 at 80° C. while stirring it with a stirrer. did. The results are shown in Table 11.

(3) Measurement of etching rate of nickel

The etching rate of nickel was determined by immersing the etching solution shown in Table 12 at 80° C. while stirring it with a stirrer, the etching time, the amount of dissolved nickel, and the contact area with the etching solution for nickel plating on the entire surface of the brass plate. was calculated from the weight difference before and after etching. The results are shown in Table 12.

From the above result, it was shown that the etching rate of the etching liquid of this invention used as a base material glass, silicon, and nickel was slower than the etching rate of titanium, titanium oxide, titanium nitride, niobium, and a tantalum nitride. From this, it was shown that the etching solution of this invention melt|dissolves titanium, titanium oxide, titanium nitride, niobium, and tantalum nitride preferentially rather than a base material.

On the other hand, the etching solution using EDTA showed that the etching rate of the underlying substrate was overwhelmingly faster than that of the etching solution of the present invention.

Test Example 11

Etching Test:

When the small piece of a gallium arsenide wafer was immersed in the thing which made the etching liquid prepared in Example 6 80 degreeC, the gallium arsenide piece melt|dissolved immediately. From this result, it was found that the etching solution of the present invention can selectively etch arsenic, gallium and gallium arsenide like titanium.

Test Example 12

Etching Test:

When a test piece of tungsten, molybdenum, ruthenium, or rhodium is immersed in the etching solution prepared in Example 6 at 80°C, it will melt immediately. From this, the etching solution of the present invention can selectively etch tungsten, molybdenum, ruthenium, or rhodium in the same way as titanium.

Test Example 13

Reuse Test:

A hairline-processed brass ring was subjected to nickel plating on both sides, and sputtering was used to form titanium oxide of 10 nm, titanium of 70 nm, silicon nitride of 45 nm, titanium nitride of 85 nm, silicon nitride of 80 nm and What was vapor-deposited 10 nm of titanium nitride in this order was used as a sample. The sample was immersed for 5 minutes in what made the etching liquid prepared in Example 6 80 degreeC, and the titanium oxide, titanium, silicon nitride, and titanium nitride which were vapor-deposited by sputtering were completely etched. After that, the sample was dried and sputtering as described above was performed again, and the same external appearance as the sample before etching was obtained. This test showed that the reuse of a sample was possible.

Example 7

Etching solution:

In 100 ml of water, 23 g of salicylic acid, 47 g of Rochelle's salt, 43 g of sodium citrate, 1 ml of PEG-200, 50 ml of hydrogen peroxide (34%) and 10 g of sodium hydroxide were dissolved. The pH of this etchant was 127.

Test Example 14

Etching Test:

The pH of the etching solution prepared in Example 7 was adjusted to the pH shown in Table 13 using sodium hydroxide or sulfuric acid. The same sample (glass cylinder) as used in Test Example 1 and the same sample (ring) used in Test Example 2 were immersed in each etchant at 50° C. until the sputtering film was completely removed by visual inspection. time was measured. The results are shown in Table 13.

It turned out that an etching rate improves, so that pH of etching liquid was high by this test. In particular, in pH 11 or more, pH 12 or more, and pH 13-14, compared with the case of less than each pH, it turned out that an etching rate improves mostly 2 times or more.

Example 8

Etching solution:

In 100 ml of water, 129 g of sodium citrate, 1 ml of PEG-2000, and 50 ml of hydrogen peroxide (34%) were dissolved. The pH of this etchant was 13.

Test Example 15

Etching Test:

A 5 cm x 5 cm x O1 cm aluminum plate or copper plate was immersed in the etching liquid adjusted in Example 8 at 50 degreeC, and it carried out similarly to Test Example 10, and measured the etching rate. It turned out that the etching rate of an aluminum plate was 130 nm/s, and the etching rate of a copper plate was 0142 nm/s.

Test Example 16

Etching Test:

When the test piece of aluminum oxide was immersed in the thing which made the etching liquid prepared in Example 8 into 60 degreeC, it melt|dissolved immediately. From this result, it was found that the etching solution of the present invention can selectively etch aluminum oxide in the same way as titanium and the like.

Test Example 17

Etching Test:

A test piece laminated by sputtering aluminum nitride and gallium nitride on a silicon wafer in this order was immersed in the etching solution prepared in Example 8 at 60° C., and the layers of aluminum nitride and gallium nitride immediately melted. From this result, it was found that the etching solution of the present invention can selectively etch aluminum nitride or gallium nitride in the same way as titanium or the like.

[0240] The principle of etching in the method of the present invention described above is estimated as follows.

(1) The role of complexing agent:

The selected complexing agent forms a chelate with the surface metal, (a) making the surface metal susceptible to nucleophilic attack, and (b) making the produced metal complex easy to dissolve in the etching solution. That is, the ligand of the selected complexing agent selectively chelates a metal (eg, titanium, niobium, etc.) suitable for the shape, orbital arrangement, and electronic properties of the metal atom to be etched, so that only a specific metal can be etched. However, when EDTA or the like, which is a commonly used complexing agent, is used, the complexing agent strongly chelates with many metals, so the selectivity is low. That is, the complexing agent selected in the present invention is one factor specifying the selectivity of the metal to be etched.

The complexing ability or selectivity of a complexing agent depends on the coordination number of the complexing agent, coordination species (nitrogen (eg, nitrogen contained in amines and nitriles), oxygen (eg, hydroxy, carboxylic acid, and oxygen contained in carbonyl)); It is determined by phosphorus, sulfur (eg, sulfur contained in mercapto and thiocarbonyl), coordination properties, electronic properties, and the ligand-ligand distance/arrangement in the case of polycoordination numbers. In the present invention, it is considered optimal to have two or three oxygen coordination molecules separated by three carbons, one hydroxy and one carboxylic acid or benzene diol. (Even in the case of three coordinating oxygen atoms, the other coordinating species is also preferably oxygen-based.) For example, if nitrogen is present in the coordinating species, titanium or niobium must be etched, but nickel is also etched, so these complexing agents It would be inconsistent with the object of the present invention.

(2) the role of the base:

Nucleophilic attack on chelated metals (e.g. hydroxide)

(3) the role of the oxidizing agent:

When bonding with each metal (M) in a metal oxide, a metal nitride, or a metal complex, the bond with the metal is oxidatively decomposed to break the lattice or non-lattice bond. (Example: M-O-M→ M-O-O-M→ 2M=O)

In the case of metal etching, the metal or metal complex is oxidized.

(eg M→ Mn+ or ligand-Mn-→ ligand-M)

[Industrial Applicability]

The method of the present invention comprises etching a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride or an alloy thereof. , Reuse of the underlying substrate or the metal, oxide of the metal, nitride of the metal, silicon nitride, hafnium nitride,

It can also be used for the recovery of tantalum nitride or alloys thereof.

Claims (6)

A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium formed on an underlying substrate selected from glass, silicon, copper and nickel, an oxide of the metal, a nitride of the metal, silicon nitride, a nitride Layers of hafnium, tantalum nitride or alloys thereof are prepared by the following formulas (I) and (II)

[In formula (I), R1 to R3 are the same as or different from each other, and -Ra, -ORb, -OORc, -COOR
d, -COOORe, -CH2COORf, -CH2COOORg, -CRhO or -CH2CHCH3 (Ra to Rh are the same as or different from each other, and are hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, an unsaturated aliphatic group having 1 to 10 carbon atoms, or It is an aryl group)]

[In formula (11), R4 to R7 are the same as or different from each other, and -Ri, -Rj, -OORk, -COORl, -COOORm, -CH2COORn, -CH2COOORo, -CRpO, -CH2CHCH3, -CN, -NC -NO2, -F, -Cl, -Br, -I, -S02Rq; or an aryl group), X is —OH, —COOH or —COOOH]
A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, said metal essentially containing at least one complexing agent selected from the compounds represented by An etching method comprising selectively etching an oxide of the metal, a nitride of the metal, silicon nitride, hafnium nitride, tantalum nitride, or an alloy thereof. The etching method according to claim 1, wherein the etching solution further contains an oxidizing agent. Formulas (I) and (II)

[In formula (I), R1 to R3 are the same as or different from each other, and -Ra
, -ORb, -OORc, -COORd, -COOORe, -CH2COORf, -CH2COOORg, -CRhO or -CH2CHCH3 (Ra to Rh are the same as or different from each other, and are hydrogen, a saturated aliphatic group having 1 to 10 carbon atoms, -10 unsaturated aliphatic group, or aryl group)]

[In formula (II), R4 to R7 are the same as or different from each other, and -Ri, -Rj, -OORk, -COORl, -COOORm, -CH2COORn, -CH2COOORo, -CRpO, -CH2CHCH3, -CN, -NC, -NO2, -F, -Cl, -Br, -I, -S02Rq; or an aryl group), X is —OH, —COOH or —COOOH]
It essentially contains at least one complexing agent selected from the compounds represented by and has a pH of 11 or more.
A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of the metal, a nitride of the metal, silicon nitride, Etching solution for hafnium nitride, tantalum nitride, or alloys thereof 4. A metal according to claim 3, again containing an oxidizing agent, a metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium, an oxide of said metal, a nitride of said metal, silicon nitride, hafnium nitride, Etching liquid for tantalum nitride or an alloy thereof. The etching method according to claim 1 or 2, wherein the pH is 12 to 14. A metal selected from titanium, niobium, tungsten, molybdenum, ruthenium, rhodium, arsenic, aluminum and gallium having a pH of 12 to 14, an oxide of said metal, a nitride of said metal, silicon nitride , an etching solution for hafnium nitride, tantalum nitride, or alloys thereof.

Images