In this work, we propose counter-doping into a p-type amorphous silicon (a-Si) film prepared by catalytic chemical vapor chemical deposition (Cat-CVD) by PH3 plasma ion implantation (PII). This method is expected to simplify the formation of p-n patterns in the back-side electrodes of interdigitated back contacted amorphous silicon (a-Si)/crystalline silicon (c-Si) heterojunction (IBC-SHJ) solar cells. In particular, we investigate the effect that hydrogen atoms implanted together with phosphorous dopants during PH3 PII have on the surface passivation properties of counter-doped p-a-Si on c-Si. Conversion in the conduction type of p-a-Si after PH3 PII is confirmed by the operation of SHJ solar cells.