Composition for Cobalt Electroplating Comprising Leveling Agent

A composition, comprising:

• (a) metal ions consisting essentially of cobalt ions, and
• (b) a leveling agent,
• wherein the leveling agent is a compound of formula L2:
• or a compound of formula L4:
• Ø-R1 (L4),
• or salts thereof,
• wherein
• R1 is selected from the group consisting of X1—CO—O—R11, X1—SO2—O—R11, X1—PO(OR11)2, and X1—SO—O—R11;
• R2, R3, R4 are independently selected from the group consisting of R1 and (i) H, (ii) aryl, (iii) C1 to C10 alkyl (iv) arylalkyl, (v) alkylaryl, and (vi) —(O—C2H3R12)m—OH, wherein if one of R2, R3 or R4 is R1, remaining R2, R3 or R4 are different from R1,
• Ø is a C6 to C14 carbocyclic or a C3 to C10 nitrogen or oxygen containing heterocyclic aryl group, which is optionally unsubstituted or substituted by up to three C1 to C12 alkyl groups or up to two OH, NH2 or NO2 groups,
• X1 is a divalent group selected from the group consisting of (i) a chemical bond (ii) aryl, (iii) C1 to C12 alkandiyl, which is optionally interrupted by O atoms, (iv) arylalkyl group —X11—X12—, (v) alkylaryl group —X12—X11—, and (vi) —(O—C2H3R12)mO—,
• R11 is selected from the group consisting of H and C1 to C4 alkyl,
• R12 is selected from the group consisting of H and C1 to C4 alkyl,
• X11 is a divalent C1 to C15 alkandiyl group,
• X12 is a divalent aryl group, and
• m is an integer from 2 to 50,
• wherein the composition is essentially free of any dispersed particles.