H-initiated extended defects from plasma treatment: Comparison between c-Si and mc-Si

In this study n- and p-type polished Czochralski-grown Si (Cz-Si) and p-type polished and as-cut multi-crystalline (mc) Si wafers have been directly H plasma treated in a plasma enhanced chemical vapour system in order to study H subsurface defect formation. Raman spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and transmission electron microscopy have been used to characterise the samples. In polished Cz-Si wafers, H induced defects were only observed up to 1 μm below the surface [1,2], while in similarly treated mc samples H induced defects were observed on grain boundaries and dislocations up to several μm below the surface [3]. It is also established that the distribution of H in the subsurface regions of the Cz-Si substrates after hydrogenation as well as the formation of structural defects depend on the type of doping. Evolution of Si-Hx bonds in hydrogenated Cz Si samples starts at 400 °C, while evolution of H initiated structural defects starts at 600 °C, when SiHx bonds are mostly dissolved.