The　key　feature　of　amorphous/crystalline　silicon　heterojunction　solar　cells　is　extremely　low　surface　recombination,　which　is　related　to　superior　passivation　on　the　crystalline　silicon　wafer　surface　using　thin　hydrogenated　amorphous　silicon　(a-Si:H)　layers,　leading　to　a　high　open-circuit　voltage.　In　this　work,　a　two-step　method　of　a-Si:　H　passivation　is　introduced,　showing　excellent　interface　passivation　quality,　and　the　highest　effective　minority　carrier　lifetime　exceeds　4500　mu　s.　By　applying　a　buffer　layer　deposited　through　pure　silane　plasma,　the　risk　of　film　epitaxial　growth　and　plasma　damage　caused　by　hydrogen　diluted　silane　plasma　is　effectively　reduced.　Based　on　this,　excellent　passivation　is　realized　through　the　following　hydrogen　diluted　silane　plasma　process　with　the　application　of　high　density　hydrogen.　In　this　process,　hydrogen　diffuses　to　a-Si/c-Si　interface,　saturating　residual　dangling　bonds　which　are　not　passivated　by　the　buffer　layer.　Employing　this　two-step　method,　a　heterojunction　solar　cell　with　an　area　of　239　cm(2)　is　prepared,　yielding　to　open-circuit　voltage　up　to　735mV　and　total-area　efficiency　up　to　22.4%.