Composition for tin or tin alloy electroplating comprising suppressing agent

A process for electrodepositing tin or a tin alloy onto a substrate by

• a) contacting a composition comprising tin ions and at least one compound of formula I with the substrate,
• wherein
• X1, X2 are independently selected from a linear or branched C1-C12 alkanediyl, which may optionally be interrupted by O or S,
• R11 is a monovalent group of formula —(O—CH2—CHR41)m—OR42,
• R12, R13, R14 are independently selected from H, R11, and R40;
• R15 is selected from H, R11, R40 and —X4—N(R2)2,
• X4 is a divalent group selected from (a) a linear or branched C1 to C12 alkanediyl, and (b) formula —(O—CH2—CHR41)o—,
• R21 is selected from R11 and R40,
• R40 is a linear or branched C1-C20 alkyl,
• R41 is selected from H and a linear or branched C1 to C5 alkyl,
• R42 is selected from H and a linear or branched C1-C20 alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl,
• n is an integer of from 1 to 6,
• m is an integer of from 2 to 250, and
• o is an integer of from 1 to 250,
• and
• b) applying a current to the substrate for a time sufficient to deposit a tin or tin alloy layer onto the substrate,
• wherein the substrate comprises features having an aperture size from 500 nm to 500 μm and the deposition is performed to fill these features.