DE2051279A1 - Aqueous solution for the electroless deposition of copper - Google Patents

Description

DR. ULRICH EQQERS

«Α» KSAiUiNq «a

BIUMENSTKASSE 13 Ut-CW ι "ίί% U

Oct. 19, 1970

P1 / Pt2

PMD CiLQiui G al a limited Broad Lane, Coventry, Warwickshire (England)

■ / Mssrig-e solution for electroless deposition of copper

The invention relates to the electroless deposition of copper and -nif solutions, v / elcüe for such deposition brew bur are, wherein the deposition particularly SiCN "(if ii-uch niciit ^ ussciiliesülicli) for Yerv / extension in the preparation of [printed bon quote ei se is suitable. ■

solutions that were previously used for the separation of stroulose tullxtscnöri copper on suitably prepared surfaces verv / endot consist ii; i generally consist of:

(a) a copper salt ijur providing a source

Copper (II) ions,
(B) eiuea icoaplex forming ends iiittel for the copper (II) ions vrie Uatriuiu-jcalium-tartrate,

(c; one reducing agent such as formaldehyde, para-orrualdehyde or a "derivative of one of these compounds,

(α) an alkali such as i-sodium hydroxide, to bring aen pH-V / ort der iöiiuug in the ar belts t; er you, noriualyrjj in. Yeruichtung / ai L der \; ixv.; jameij. l'dtijicoit there,

109829 / 1S62

BAD ORlGiNAL

udeiL Kittels , and (e) buffer connections as required,

However, solutions tend to include the following components. to have: '■

(i) they are not beeondars stable,

(ii) they do not part with ever faster '

Speed from,

(iii) the rate of deposition is increasing gev / öhnlioli during the proceedings onne, iiüc ^ üicht whether the constituents have been reopened.

to be or not »

It was now bound that solutions of this general ^ _t , · jü ■ can be improved by the incorporation of zealous or / or higher additions, from which it is to be taken that di.ys ci-ials surface-renoactive drugs can act, xuA / odui ' ■ tou further konplexbildendan llitteln, .utii the copper (H) ion ', ■ öngei ¹ au bind "regardless of these theoretical 13e <. -. Attention was found that triethanolamine as Zuy;., t; a. is particularly suitable for solutions for electroless copper deposition * aminopropionic acid, glycine, ethylenediarain ,,,, ■■ ■ (sodium) -thiοcyancit, dihydroxyeth ^^ iglycine, Ilethyl-ethyl-ethylenediamine, iithyl-ethylenediamine, 2-I-iydroxyäthyl-fi, thylercdial2line, , ■; Pentamethylenediamine, glutamic acid and amino tetraacetic acid: should, however, also be useful. It can be observed that these compounds are mainly amines (including polyamines) or substituted amines, which are soluble in water or in alkaline-aqueous solution, and for complexes uit Copper (II) ions have stability a ^ onstants awiaolien 3 and 1Ü. It may be possible to use these in part of the hot oimiliohen koiaplex-forming agents such as iratriuia * -kaliru.i ^ tartrut

It is also possible to incorporate a stabilizer, in addition to the speedier Bq just described

109829/1562

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ri.:^j :: I '-. o ^ jeütrntionei: present su rope; ur-ocl.er., v / i6 uieö ■;. "" I! u ^ :. fol eiideri Bei.-3 iel eröicitj.icli. is.

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eae- .. door:

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.tldenyd 1 ^

!, 'utx'iu.acarbonat 5 t _;

"iutriu :: ij ..- ^r drox, vd- ■ 12 j

", barrels" up to 1 liter of solution v.ifgerillt

Stabilizer- luitriu ^ thiosuliat Ü, 7i? Eife

ilutcun, .addition - Isopropylul.-. x.01 4.0 cvd

ij: -3 ", atriviucarbonat oeai ΐ; · Ί; eiui _v - 3t DiI" .siex "end'2 'Virkui

ui ,: ^ allows a wider / ui'ii:. "« ·. υ · - ;. ' th. steer the --Γ. it-x "en components ο

.ji-3. ·. «LöciUiit ;. ioreiaet --iu-to.; / Lal '. - · .. 'An.yL-a * miu' einor

109829/1562

BATH ORIGINAL

~, 4

suitably prepared (sensitized and activated) surface, irrespective of whether it is conductive or non-conductive, the deposition rate being about 4 microns per hour at 2O ⁰ O., Eies © speed

can be varied by changing the ratio of stabilizer to accelerator and is independent of the precipitation dioke ₀

The solution can be used to treat relatively large surface areas of a suitably prepared material

ρ become; 7 dm can be treated in 1 liter of solution. So far, many formulations have had the disadvantage that considerably smaller surface areas per unit volume could not be exceeded and an increase led to a loss of stability, to irregular deposition rates and, as a consequence, to a loss of the deposition quality. "The solution can be replenished in terms of each of its components and therefore maintains the same performance over long periods of work." The solution is also stable, separates continuously at high speeds and works at temperatures as low as 18 ⁰ O.

The solution works at predetermined absorption rates even in the presence of large amounts of such substances, which are normally referred to as "catalyst poisons". Organic or inorganic compounds containing oyanides, organic or inorganic sulfur-containing compounds or even compounds containing both cyanide and sulphurous compounds are pale to such substances * Contains atoms. These connections could under normal circumstances the separation and the stability of the IiOiUM and
serious-

In their preferred

109829 / 15S2

-20S1279

can be summarized as creating a "basic, aqueous bath for the electroless deposition of copper, the bath containing a source of copper (II) ions} a complexing agent for these ions in order to make them soluble in alkaline solution; a source of hydroxyl radicals \ a reducing agent such as formaldehyde; the Abscheidungsgeachwindigkeit, the stability of the bath and the quality control of the deposition and additional micro additives, such as a sulfur compound having two densely located sulfur atoms in the molecule is a tertiary amine, and a lower, \ tfasserlö seeker Alkonol «, the preferred concentrations are up to 0.15 Hol copper (II) ion per liter, at least 0.03 Hol reducing agent per liter, at least 0.05 Hol complexing agent (Hochßlleaalz) per liter, and the preferred pH value is 12 to 15o The concentrations of the micro-additives are desirably those as set out in the example »

· * Claims

10882 «/ 1562

Claims (8)

Claims M) J Aqueous solution for the electroless deposition of copper, v / calibrate a source of copper (II) ions, a koiaplex-forming agent for copper (II) ions, a reducing agent and a Contains base to adjust the pH to the working range, characterized by the presence of a small Part of an accelerator, which is a stability constant for complexes with copper (II) ions of between 3 and 10 owns » 2) Solution according to claim 1, characterized in that the dasa Accelerator is a tertiary ainin » 3) solution according to claim 2, 'characterized in that the Triethanolamine is accelerator ", 4) solution according to claim 2 or 3, characterized in that the complexing agent is Rochelle salt, 5) solution according to any one of the preceding claims, characterized characterized in that the accelerator is present in a concentration of around 0.7 mg per liter, 6) solution according to one of the preceding claims, characterized by the presence of a small amount of a stabilizer such as a compound which has two in the molecule. has sulfur atoms located close together. 7) solution according to claim S _9, characterized in that the stabilizer is sodium thiοsulfate. 8) solution according to claim 7, characterized in that the Stabilizer is present in a concentration of about 0.75 milligrams per liter. t ~ »r ~ \ t j ν ß m 11 -ι ι (\ j / 4 ι BATH ORIGINAL 10M28 / U62 y) Solution according to one of the preceding claims, gei ^ enn- zeiulmet durcxi uie Aiiweseiiiieit a small amount of a lower, \ msBerlösliolien AU: u1io1s as a smoothing agent " nacii Claims 9, characterized in that 3 the amount of alcohol about 4 Ω per liter is ₀ BATH ORIGINAL