Crystalline chromium alloy deposit

• US 8,187,448 B2
• Filed: 10/02/2008
• Issued: 05/29/2012
• Est. Priority Date: 10/02/2007
• Status: Active Grant

• Current Assignee: Atotech Deutschland GmbH (MKS Instruments Incorporated)
• Original Assignee: Atotech Deutschland GmbH (MKS Instruments Incorporated)
• Inventors: Rousseau, Agnes, Bishop, Craig V.
• Primary Examiner(s): Wong, Edna
• Application Number:
  US12/244,327
• Publication Number:
  US 20090114544A1
• Time in Patent Office: 1,335 Days
• Field of Search: 205/243, 205/283, 205/287, 205/289, 205/290
• US Class Current: 205/243
• CPC Class Codes: C25D 3/06 from solutions of trivalent chromium
• CPC Class Codes: C25D 3/10 characterised by the organic bath constituents used

Abstract

An electrodeposited crystalline functional chromium deposit which is nanogranular as deposited, and the deposit may be both TEM and XRD crystalline or may be TEM crystalline and XRD amorphous. In various embodiments, the deposit includes one or any combination of two or more of an alloy of chromium, carbon, nitrogen, oxygen and sulfur; a {111} preferred orientation; an average crystal grain cross-sectional area of less than about 500 nm²; and a lattice parameter of 2.8895+/−0.0025 A. A process and an electrodeposition bath for electrodepositing the nanogranular crystalline functional chromium deposit on a substrate, including providing the electrodeposition bath including trivalent chromium, a source of divalent sulfur, a carboxylic acid, a source of nitrogen and being substantially free of hexavalent chromium; immersing a substrate in the bath; and applying an electrical current to electrodeposit the deposit on the substrate.

Claims

1. A process for electrodepositing a nanogranular functional crystalline chromium alloy deposit on a substrate, comprising:

providing an electrodeposition bath, wherein the bath is prepared by combining ingredients comprising trivalent chromium, a source of divalent sulfur, a carboxylic acid, a source of sp³ nitrogen, wherein the bath is substantially free of hexavalent chromium;

immersing a substrate in the electroplating bath; and

applying an electrical current to electrodeposit a functional crystalline chromium alloy on the substrate, wherein the chromium alloy comprises chromium, carbon, nitrogen, oxygen and sulfur, and the chromium alloy is crystalline and nanogranular as deposited;

wherein the source of divalent sulfur is present in the electrodeposition bath at a concentration from about 0.0001 M to about 0.05 M and the electrodeposition bath comprises a pH in the range from 5 to about 6.5.

2. The process of claim 1 wherein the chromium alloy is both TEM and XRD crystalline.

3. The process of claim 1 wherein the chromium alloy is TEM crystalline and is XRD amorphous.

4. The process of claim 1 wherein the chromium alloy comprises one or any combination of two or more of:

a {111} preferred orientation;

an average crystal grain cross-sectional area of less than about 500 nm²; and

a lattice parameter of 2.8895+/−

0.0025 A.

5. The process of claim 1 wherein the chromium alloy comprises from about 0.05 wt. % to about 20 wt. % sulfur.

6. The process of claim 1 wherein the chromium alloy comprises from about 0.1 to about 5 wt % nitrogen.

7. The process of claim 1 wherein the chromium alloy comprises an amount of carbon less than that amount which renders the chromium alloy amorphous.

8. The process of claim 1 wherein the chromium alloy comprises from about 0.07 wt. % to about 1.4 wt. % sulfur, from about 0.1 wt. % to about 3 wt. % nitrogen, from about 0.5 wt. % to about 7 wt. % oxygen, and from about 0.1 wt. % to about 10 wt. % carbon.

9. The process of claim 1 wherein the chromium alloy remains substantially free of macrocracking when subjected to a temperature of at least 190°

C. for at least 3 hours and has a thickness in the range from about 3 microns to about 1000 microns.

10. The process of claim 1 wherein the source of sp³ nitrogen comprises ammonium hydroxide or a salt thereof, a primary, secondary or tertiary alkyl amine, in which the alkyl group is a C₁-C₆ alkyl, an amino acid, a hydroxy amine, or a polyhydric alkanolamines, wherein alkyl groups in the source of nitrogen comprise C₁-C₆ alkyl groups.

11. The process of claim 1 wherein the carboxylic acid comprises one or more of formic acid, oxalic acid, glycine, acetic acid, and malonic acid or a salt of any thereof.

12. The process of claim 1 wherein the source of divalent sulfur comprises one or a mixture of two or more of:

thiomorpholine,

thiodiethanol,

L-cysteine,

L-cystine,

allyl sulfide,

thiosalicylic acid,

thiodipropanoic acid,

3,3′

-dithiodipropanoic acid,

3-(3-aminopropyl disulfanyl)propylamine hydrochloride,

[1,3]thiazin-3-ium chloride,

thiazolidin-3-ium dichloride,

a compound referred to as a 3-(3-aminoalkyl disulfenyl)alkylamine having the formula;

R₃N^⊕

—

(CH₂)_n—

S—

S—

(CH₂)_m−

^⊕

NR¹₃2X^⊖

wherein R and R¹ are independently H, methyl or ethyl and n and m are independently 1-4;

or

a compound referred to as a [1,3]thiazin-3-ium having the formula;

13. The process of claim 1 wherein the applying an electrical current is carried out for a time sufficient to form the chromium alloy to a thickness of at least 3 microns.

14. An electrodeposition bath for electrodepositing a functional nanogranular crystalline chromium alloy, wherein the chromium alloy comprises chromium, carbon, nitrogen, oxygen and sulfur, and

the bath comprises an aqueous solution obtained by combining ingredients comprising:

a source of trivalent chromium having a concentration of least 0.1 molar and being substantially free of added hexavalent chromium;

a carboxylic acid;

a source of sp³ nitrogen;

a source of divalent sulfur, at a concentration in the range from about 0.0001 M to about 0.05 M; and

wherein the bath further comprises;

a pH in the range from 5 to about 6.5;

an operating temperature in the range from about 35°

C. to about 95°

C.; and

a source of electrical energy to be applied between an anode and a cathode immersed in the electrodeposition bath.

15. The electrodeposition bath of claim 14 wherein the source of divalent sulfur comprises one or a mixture of two or more of:

thiomorpholine,

thiodiethanol,

L-cysteine,

L-cystine,

allyl sulfide,

thiosalicylic acid,

thiodipropanoic acid,

3,3′

-dithiodipropanoic acid,

3-(3-aminopropyl disulfanyl)propylamine hydrochloride,

[1,3]thiazin-3-ium chloride,

thiazolidin-3-ium dichloride,

a compound referred to as 3-(3-aminoalkyl disulfenyl)alkylamine having the formula;

R₃N^⊕

—

(CH₂)_n—

S—

S—

(CH₂)_m—

<sup>⊕

NR1</sup>₃2X^⊖

wherein R and R¹ are independently H, methyl or ethyl and n and m are independently 1-4;

or

a compound referred to as a [1,3]thiazin-3-ium having the formula;

16. The electrodeposition bath of claim 14 wherein the source of electrical energy is capable of providing a current density of at least 10 A/dm² based on an area of substrate to be plated.

17. The electrodeposition bath of claim 14 wherein the bath contains a quantity of the source of nitrogen sufficient that the chromium alloy comprises from about 0.1 to about 5 wt % nitrogen.

18. The electrodeposition bath of claim 14 wherein the bath contains a quantity of the carboxylic acid sufficient that the chromium alloy comprises an amount of carbon less than that amount which renders the chromium alloy amorphous.

19. The electrodeposition bath of claim 14 wherein the bath contains a quantity of the source of divalent sulfur, the source of nitrogen and the carboxylic acid sufficient that the chromium alloy comprises from about 0.05 wt. % to about 1.4 wt. % sulfur, from about 0.1 wt. % to about 3 wt. % nitrogen, from about 0.5 wt. % to about 7 wt. % oxygen, and from about 0.1 wt. % to about 10 wt. % carbon.

20. The electrodeposition bath of claim 14 wherein the carboxylic acid comprises one or more of formic acid, oxalic acid, glycine, acetic acid, and malonic acid or a salt of any thereof.

21. The electrodeposition bath of claim 14 wherein the source of sp³ nitrogen comprises ammonium hydroxide or a salt thereof, a primary, secondary or tertiary alkyl amine, in which the alkyl group is a C₁-C₆ alkyl, an amino acid, a hydroxy amine, or a polyhydric alkanolamines, wherein alkyl groups in the source of nitrogen comprise C₁-C₆ alkyl groups.

22. The electrodeposition bath of claim 14 wherein the bath comprises the source of divalent sulfur at a concentration sufficient to obtain either (a) a chromium alloy that is both TEM and XRD crystalline, as deposited or (b) a chromium alloy that is TEM crystalline and XRD amorphous, as deposited.