An electroless copper plating bath for depositing a copper or copper alloy layer on a surface of a substrate, comprising a) copper ions; b) at least one reducing agent suitable for reducing copper ions to metallic copper; and c) at least one complexing agent for copper ions; characterized in that the electroless copper plating bath comprises d) at least one compound according to formula : wherein Z 1 and Z 2 are independently selected from the group consisting of hydrogen; carboxylic acid group; carboxylate group; sulfonic acid group; sulfonate group; substituted or non-substituted carboxamide group; nitrile group; nitro group; substituted or non-substituted trialkylammonium group; substituted or non-substituted 2-carboxyvinyl group; substituted or non-substituted 2-vinylcarboxylate group; substituted or non-substituted 2-(trialkylammonium)vinyl group; substituted or non-substituted hydroxamic acid group; and substituted or non-substituted oxime group; with the proviso that at least one of Z 1 and Z 2 is not hydrogen; and wherein R 1 , R 2 , R 3 and R 4 are defined as follows: i. R 1 , R 2 , R 3 and R 4 are hydrogen; or ii. R 1 with R 2 are forming together a substituted or non-substituted aromatic ring moiety, R 3 and R 4 are hydrogen; or iii. R 3 with R 4 are forming together a substituted or non-substituted aromatic ring moiety, R 1 and R 2 are hydrogen; or iv. R 1 with R 2 as well as R 3 with R 4 are forming together a substituted or non-substituted aromatic ring moiety, respectively. a) copper ions; b) at least one reducing agent suitable for reducing copper ions to metallic copper; and c) at least one complexing agent for copper ions; characterized in that the electroless copper plating bath comprises d) at least one compound according to formula : wherein Z 1 and Z 2 are independently selected from the group consisting of hydrogen; carboxylic acid group; carboxylate group; sulfonic acid group; sulfonate group; substituted or non-substituted carboxamide group; nitrile group; nitro group; substituted or non-substituted trialkylammonium group; substituted or non-substituted 2-carboxyvinyl group; substituted or non-substituted 2-vinylcarboxylate group; substituted or non-substituted 2-(trialkylammonium)vinyl group; substituted or non-substituted hydroxamic acid group; and substituted or non-substituted oxime group; with the proviso that at least one of Z 1 and Z 2 is not hydrogen; Z 1 and Z 2 are independently selected from the group consisting of hydrogen; carboxylic acid group; carboxylate group; sulfonic acid group; sulfonate group; substituted or non-substituted carboxamide group; nitrile group; nitro group; substituted or non-substituted trialkylammonium group; substituted or non-substituted 2-carboxyvinyl group; substituted or non-substituted 2-vinylcarboxylate group; substituted or non-substituted 2-(trialkylammonium)vinyl group; substituted or non-substituted hydroxamic acid group; and substituted or non-substituted oxime group; with the proviso that at least one of Z 1 and Z 2 is not hydrogen; i. R 1 , R 2 , R 3 and R 4 are hydrogen; or ii. R 1 with R 2 are forming together a substituted or non-substituted aromatic ring moiety, R 3 and R 4 are hydrogen; or iii. R 3 with R 4 are forming together a substituted or non-substituted aromatic ring moiety, R 1 and R 2 are hydrogen; or iv. R 1 with R 2 as well as R 3 with R 4 are forming together a substituted or non-substituted aromatic ring moiety, respectively. <EOS>