Design and Achievement of Superfilling Electroless Silver Deposition for Micrometer Trenches

Electroless silver bottom-up filling has been designed and investigated by linear sweep voltammetry. It was found that the addition of polyethylene glycol 4000 (PEG 4000) had a good inhibitory effect on the electrode reaction. Experiments showed that PEG 4000 had a strong depressing action in electroless silver deposition. Specifically, when the PEG 4000 concentration was 1.0 mg/L, the plating rate of electroless silver decreased from 5.7 to 2.3 μm/h. The bottom-up silver fillings for different-sized trenches were achieved in an electroless plating bath with the addition of PEG 4000. The trenches analysis showed that all microtrenches with different widths were completely filled by electroless silver plating.