Hydrogen plasma-treated as-cut and chemically etched multicrystalline silicon samples were studied by electron microscopy in order to investigate hydrogen defect formation at extended bulk defects. In chemically etched samples, the texture of the surface after hydrogen plasma treatment differs between different grains depending on grain orientation. In as-cut samples, hydrogen induced defects were formed on sawing defects that extended up to ∼5μm below the Si surface. Intragranular defects were also observed in the ∼1μm sub-surface region. The density of defects was higher in as-cut samples than in chemically etched samples and the size of the defects increased with depth. Hydrogen induced structural defects on bulk dislocations and on dislocations in twin grain boundaries and stacking faults were found several microns below the sample surface. It was concluded that (i) the passivation efficiency of multicrystalline silicon substrates after H plasma treatment could be limited by the formation of hydrogen induced structural defects and that (ii) such defects could be used to getter unwanted impurities upon high temperature processing of the Si wafers.

Transmission Electron Microscopy Study of Hydrogen Defect Formation at Extended Defects in Hydrogen Plasma Treated Multicrystalline Silicon. H.Nordmark, R.Holmestad, J.C.Walmsley, A.Ulyashin: Journal of Applied Physics, 2009, 105[3], 033506