DE2204326B2 - Aqueous acid bath for the galvanic deposition of shiny and ductile copper coatings - Google Patents

Description

I.

R ₂ -PR ₄

ΟΗ ^Θ

10

15th

in which Ri, R2, R3 and R _{4 are} identical or different and represent an optionally mono- or polysubstituted aromatic, aliphatic, cycloaliphatic or heterocyclic hydrocarbon radical and Ri and R2 together with the phosphorus atom represent a mononuclear or polynuclear heteroxyclic radical, or their Salt with an inorganic or organic acid.

2. Aqueous acid bath for the galvanic deposition of shiny and ductile copper coatings, which contains an organic phosphorus compound, characterized by a content of a «1 Compound of the general formula

Ri

I.

P-RJ

Ri

4 (i

in which Ri ', R2', R3 'and R ₄ ' are identical or different and a lower alkyl radical optionally substituted by halogen, an amino group or a hydroxyl group, a benzyl radical, a cyanobenzyl radical, a cycloalkyl radical having 5 to 8 carbon atoms, a lower carboxyalkyl radical , a lower naphthylalkyl radical, a lower trialkylphosphoniumalkyldiphenylalkyl radical or a lower alkenyl radical, R 'and R2' together with the phosphorus atom form the phosphorus v) phindolinium radical and X is a hydroxyl ion or an acid anion, preferably a halogen ion, a monovalent one Represents a sulfate ion equivalent, a methyl sulfate ion, a nitrate ion or an acetate ion.

3. Aqueous acid bath for galvanic deposition> formation of shiny and ductile copper coatings, which is an organic phosphorus compound contains, characterized by a content of a compound of the general formula

R "

I ,. r; ¹ - p - r _; —Υ "

Rj '

in which Ri ". R ₂ " and Rj "are identical or different and an optionally monosubstituted or polysubstituted aromatic, aliphatic, cycloaliphatic or heterocyclic monovalent hydrocarbon radical, Rs an optionally monosubstituted or polysubstituted aromatic, aliphatic or cycloaliphatic divalent hydrocarbon radical and Y mean an acid anion.

4. Aqueous acidic bath according to claim 3, characterized in that Ri ", R2" and R3 "are identical or different and have a lower alkyl radical, optionally substituted by halogen, an amino group or a hydroxyl group, a benzyl radical, a cyanobenzyl radical, a cycloalkyl radical 5 to 8 carbon atoms, a lower carboxyalkyl radical, a lower naphthylalkyl radical, a lower trialkylphosphoniumalkyldiphenylalkyl radical or a lower alkenyl radical; R _{5 represents} an aliphatic hydrocarbon radical with preferably 1 to 4 carbon atoms, optionally interrupted by O atoms, and Y represents the acid ester radical of sulfuric acid , sulfurous acid, phosphoric acid, phosphorous acid or a carboxylic acid.

5. Aqueous acidic bath according to claims 1 to

4, characterized in that this the phosphonium compounds in amounts of 0.01 to 10.0 g / liter, preferably from 0.2 to 2.0 g / liter.

6. Aqueous acidic bath according to claims 1 to

5, characterized in that this additionally thio and / or selenium compounds with water-soluble making groups in amounts of 0.0005 to 0.2 g / liter as glass formers, nitrogen-containing thio compounds or polymeric phenazonium compounds in amounts of 0.0005 to 0.2 g / liter as a leveler and optionally wetting agents.

The invention relates to an aqueous acidic bath for the electrodeposition of shiny and ductile Copper plating using high current densities containing an organic phosphorus compound.

It is known that acidic, especially the most common sulfuric acid copper electrolytes can add small amounts of certain organic substances. Mm instead of a crystalline matt Deposition to obtain shiny copper coatings. Most of the proposals were made for this purpose organic thio compounds, such as. B. derivatives of acidic sulfur-containing phosphorus derivatives (DE-PS 464 and 12 01 152) and organic sulfides with at least one sulfonic acid group in the mixture or in chemical bond with a polyether (DE-AS 21 062). An aqueous acidic bath for galvanic Deposition of copper coatings, which is an organic Contains phosphorus compound is also known from DE-PS 11 68 208.

Such compounds have only proven to be of practical use when they are used in combination with a high molecular weight, oxygen-containing compound. One disadvantage here, however, is that the applicable current densities are tight limits, which are generally not more than 8 A / dm ² . At higher current densities, the copper coating usually becomes powdery and therefore unusable as a result of the co-deposition of hydrogen.

Baths that allow the use of high current densities are increasingly required, because in this way a certain layer thickness can be deposited in shorter exposure times can. This means with an existing copper plating plant an increased throughput of goods or a space saving when planning a new system, because for a specific, intended throughput of goods, the size or number of bath containers is reduced can be.

The invention is therefore based on the object of developing a bath that makes the deposit shiny and allows ductile copper coatings even when using high current densities

This object is achieved according to the invention by an aqueous acidic bath which is an organic one Contains phosphorus compound, and this is characterized is that it is a quaternary phosphonium base of the general formula

R ₁

R ₂ -PR ₄

R ₃

ΟΗ ^Θ

(D

Ri-PR ₄

(ID

15 is a cycloalkyl radical with 5 to 8 carbon atoms, a lower carboxyalkyl radical, a lower naphthylalkyl radical, a lower trialkyl-phosphonium-alkyldiphenyl-alkyl radical or a lower alkenyl radical, Ri 'and R2' together with the phosphorus atom form the phosphindolinium radical and X is a hydroxyl ion or an acid anion, preferably a Halogen ion, a monovalent sulfate ion equivalent Represents methyl sulfate ion, a nitrate ion or an acetate ion

The compounds which can be used according to the invention also include the internal quaternary salts of the marked phosphonium bases, these are so-called betaines, which of the following general ones Formula correspond to:

JIl

in which Ri, R2, R3 and R _{4 are} identical or different and represent an optionally mono- or polysubstituted aromatic, aliphatic, cycloaliphatic or heterocyclic hydrocarbon radical and Ri and R2 together with the phosphorus atom represent a mononuclear or polynuclear heterocyclic radical, or whose salt with an inorganic or η organic acid contains.

Such salt-forming acids come, for. B. possible: hydrochloric acid, hydrobromic acid, hydriodic acid, Sulfuric acid, nitric acid, methylsulfuric acid or acetic acid.

Particularly suitable additives are those compounds which are characterized by the general formula

■ ti

in which R /, R2 ', Rj' and R ₄ 'are identical or different and contain a lower alkyl radical, a benzyl radical, a cyanobenzyl radical, Ri' which is optionally substituted by halogen, an amino group or a hydroxyl group

R ₂ '-PR ₅ -Υ ^θ
R ₃ '

(JS)

in which Ri ", R2" and R3 "are identical or different and an optionally mono- or polysubstituted aromatic, aliphatic, cycloaliphatic or heterocyclic monovalent hydrocarbon radical, Rs an optionally mono- or polysubstituted aromatic, aliphatic or cycloaliphatic bivalent hydrocarbon radical and Y is an acid anion.

Of these, particular mention should be made of those compounds in which in formula (III) Ri ", R2" and R3 "are identical or different and contain a lower alkyl radical, a benzyl radical, a cyanobenzyl radical, a lower alkyl radical, optionally substituted by halogen, an amino group or a hydroxyl group Cycloalkyl radical with 5 to 8 carbon atoms, a lower carboxyalkyl radical, a lower naphthyl radical, a lower trialkylphosphoniumalkyl-diphenyl-alkyl radical or a lower alkenyl radical, R5 is an aliphatic hydrocarbon radical optionally interrupted by O atoms and preferably 1 to 4 carbon atoms and Y represents the acid ester radical Sulfuric acid — O · SO ₃ ⁰ , sulfurous acid —SO3®, phosphoric acid —O · PO ₃ ⁹ , phosphorous acid - Ρ0 ₃ ^θ or a carboxylic acid - COO ^e .

The compounds to be used according to the invention are known per se or can be used per se known methods are produced, e.g. B. by reacting the corresponding tertiary phosphine compounds with organic halides or sulfonic acid esters.

The following table lists compounds to be used according to the invention.

Table I.

1. Tetrabutylphosphonium chloride

2. Tctruäthylphosphoniumsulfat

3. Tributyl-benzylphosphonium chloride

t (C ₄ H ₉ ) ₄ P®] CP

(C ₄ H ₉ ) ^ - CH ₂ -V ^- A

continuation

4. Tricyclohexyl-benzylphosphonium bromide

5. Tris (hydroxymethyl) butyl phosphonium bromide

6. Methyl diethyl carboxymethylphosphonium iodide

7. Triethyl-jS-chloroethyl-phosphonium chloride

8. Triethyl-β-aminoethyl-phosphonium chloride

9. Triphenyi-propylsulfophosphoniumbeatine

10. Trimethyl-acetophosphonium betaine

11. 1,1-Diethyl-phosphindolinium bromide

12. Tributyl- ^ S-naphthylmethylphosphonium bromide

13. Bis- (2,2'-tributyl-phosphonionomethyl) -diphenyl-dichloride

14. Tributyl-cyanobenzylphosphonium chloride

15. Tributyl-carbmethoxymethylphosphonium chloride

16. Tributyl-propylsulfophosphonium betaine

17. Tetrabutyl phosphonium methyl sulfite

18. Tributyl-allyl-phosphonium chloride

Of these, the best effect is shown by those compounds which are not aromatic on the phosphorus atom Groups included.

A sulfuric acid copper sulfate solution of the following composition is generally used as a bath for the deposition of copper coatings with the addition of the substances according to the invention:

Copper sulfate CuSO ₄ · 5 H ₂ O 100-280 g / liter sulfuric acid H ₂ SO ₄ 20-100 g / liter

Instead of copper sulfate, other copper salts can also be used. The sulfuric acid can be partially or

H> P * -CK, ^ ^

Bt "

[(HOC H ₂ J ₃ P * - C ₄ H ₉ ] Br ⁹

CH ₃

* "- COOCH ₃

(C ₂ H ₅ J ₂

Cl ^e
[(C ₂ Hs) ₅ P * - (CH ₂ J ₂ NH ₂ ] Cl ⁹

<^)> = P ^ - (CH ₂ J ₃ SOf
(CH ₃ J ₃ P * • CH ₂ COO ⁶

Br ⁹

Br ⁹

^ f-CH ₂ -P * (C ₄ H,) ₃ '\ - CH ₂ - P ^ (C ₄ H ₉ J ₃

2Cl ^e

(C ₄ H ₉ J ₃ ^ -CH ₂

CN | Cl ^e

^b5 [(C ₄ H ₉ J ₃ P * - CH ₂ COOCH ₃ ] Cl ⁹
(C ₄ H ₉ J ₃ P * (CH ₂ J ₃ SO?
[(C ₄ H ₉ J ₄ P *] CH ₃ O - SO?

[(C ₄ H ₉ J ₃ P * ■ CH ₂ CH = CH ₂ ] Cl®

be replaced entirely by fluoroboric acid, phosphoric acid and / or other acids. The electrolyte can be chloride-free or - which is usually beneficial for improving gloss and leveling - Chlorides, e.g. B. alkali chlorides or hydrochloric acid Contained in amounts from 0.001 to 0.5 g / liter.

If one or more of the substances according to the invention are added to such copper baths, the cathodic current density can be ^{increased to over 8 A / dm 2} without causing errors, in particular avoiding a loosely adhering, powdery copper deposition in the range of high current densities

will. Above all, however, the throwing power of the baths can be considerably improved, so that one can also use a lot low current density ranges which would remain uncovered without the addition of these substances, a satisfactory copper deposition is obtained. This can also be significantly above room temperature Electrolyte temperatures up to about 45 ° C can be used.

The compounds to be used according to the invention are added to the copper bath in amounts of 0.01 g / liter to 10.0 g / liter, preferably from 0.2 to 2.0 g / liter, added, but can also be used from case to case even lower or higher concentrations can be used.

However, the substances to be used according to the invention are also particularly suitable in connection with other, conventional brighteners and / or wetting agents, fog-free and high-gloss copper coatings Application of very high current densities to deposit.

Table II

Hl A particularly significant increase in the current densities obtained, for. B. when these substances are used together with the organic thio and / or selenium compounds known per se as brighteners. The so-called phenazonium compounds or others are suitable as further additives.

The amounts of additives can be within the following limits:

Thio and / or selenium compounds with water-solubilizing groups:

0.0005-0.2 g / liter,

preferably 0.01-0.1 g / liter,

nitrogenous thio compounds, phenazonium compounds:

0.0005-0.2 g / liter, preferably

0.0005-0.02 g / liter.

Table II contains examples of thio and selenium compounds with water-solubilizing groups.

C ₂ H ₅

1. N, N-diethyl-diethiocarbamic acid (<y-sulfopropyl) ester, Sodium salt

2. Mercaptobenzothiazole-S-propylsulfonic acid, sodium salt

3. 3-mercaptopropane-1-sulfonic acid, sodium salt

4. thiophosphoric acid-0-ethyl-bis (<y-sulibpropyl) -ester, Disodium salt

C • S (CH ₂ I ₃ SO ₃ Na

C ₂ H ₅

S- (CH ₂ ) JSO ₃ Na

HS- (CH ₂ ) JSO ₃ Na

OC ₂ H ₅
S = P-OCH ₂ CH ₂ CH ₂ SO ₃ Na

OCH ₂ CH ₂ CH ₂ SO ₃ Na
O (CH ₂ ) j SO ₃ Na

/ 5. Thiophosphoric acid tris - ((ε-sulfopropyl) ester, trisodium salt S = P-O (CH _{2 I 3} SO ₃ Na

Q (CH ₂ ) JSOjNa

6. Isothiocyanopropylsulfonic acid, sodium salt

7. Thioglycolic acid, potassium salt

S = C = N (CH ₂ ) j SO ₃ Na
HS CH ₂ COOK

8. S, S-bis (sulfophenyl) disulfide, disodium salt

NaO ₃ S

-SO ₃ Na

9. Bis (sulfopropyl) diselenide, dipotassium salt KO ₃ S • (CH 1 Se-Se (CH ₂ J ₃ • SO ₃ K

Table III contains examples of nitrogen-containing thio compounds and polymeric phenazonium compounds. Table III
1. Thiourea H ₂ N · CS · NH ₂

2. N-acetylthiourea

3. N-trifluoroacetylthiourea T.

4. N-ethylthiourea

5. N-cyanoacetylthiourea

CH ₃ CO -NH-CS-NH ₂
CF ₃ CO -NH-CS-NH ₂
C ₂ H ₅ NH • CS • NH ₂
NC - CH ₂ -CO-NH-CS • NH ₃

continuation

6. o-Tolylthiourea

7. Ν, Ν'-ButylenethiourtolT

CH ₃

CS NH ₂

8. Thiazolidinthione

9. Thiazolthiol

10. Imidazolidinthione- (2) (ethylene thiourea)

11. 6-methyl-2-pyrimidine thioI

12. Poly (2-methyl-7-dimethylaminophenazonium sulfate) -NH

13. Poly (2-methyl-7-dimethylamino-5-phenyl-phenazonium sulfate

CH ₃

(CHj) ₂ N

(CHj) ₂ N

CH ₃

CH,

The specified compounds can also be in the corresponding tautomeric form.

The following examples explain the use according to the invention of the compounds identified.

■ 55

example 1

In a copper bath of the composition

g / liter of copper sulfate CuSO ₄ · 5 H ₂ O 55 g / liter of concentrated sulfuric acid

if you get dull deposits with unsatisfactory throwing power this bath

1 g / liter tributyl-carbmethoxymethylphosphonium chloride

added, the throwing power is so greatly improved.

W) that a complete copper coating is deposited even in depressions of the workpiece to be copper-plated, in which the current density is less than 01 A / dm ^2.

Example 2

The following electrolyte provides shiny, well-leveled precipitates up to a current density of 14 A / dm ² at a bath temperature of 40 ^{° C.}

220 g / liter of copper sulfate CuSO ₄ · 5 H ₂ O 60 g / liter of concentrated sulfuric acid 40 mg / liter of sodium chloride

1 g / liter tributyl-benzyl-phosphonium chloride 10 mg / liter mercaptopropane sulfonic acid,

Sodium salt

6 mg / liter of polymeric 2-methyl-7-dimethylamino-5-phenyl-phenazonium sulfate

Example 3

Particularly high current densities and thus a high deposition rate can be achieved in a bath achieve the following composition:

220 g / liter of copper sulfate CuSO ₄ ■ 5 H ₂ O 60 g / liter of concentrated sulfuric acid 40 mg / liter of sodium chloride

1 g / liter tetrabuiylphosphonium chloride 20 mg / liter thiophosphoric acid-tris (co-sulfo-

prqpyl) ester, sodium salt 0.6 mg / liter N-ethylthiourea

At a bath temperature of 40 ^° C., very well leveled precipitates are obtained up to current densities of 16 A / dm ^2. In this way, a good level of depth of shine is evenly achieved.

Claims (1)

Patent claims: 1. Aqueous acid bath for the galvanic deposition of shiny and ductile copper coatings, which contains an organic phosphorus compound, characterized in that it a quaternary phosphonium base of the general formula