H implantation in Si/Si:B/Si structures is a promising route to improve the Smart Cut™ process and transfer thin Si layers of reduced roughness and controlled thickness onto regular Si wafers. However, the mechanisms driving this process are unknown and thus difficult to model or optimize. For this reason, we have experimentally studied the redistribution of H which takes place in such structures after implantation and during annealing using SIMS and TEM. We show that the Si:B layer already traps H during implantation and form platelets parallel to the wafer surface. During annealing, the H atoms implanted in the Si regions are slowly transferred toward the Si:B layer where they are trapped on large platelets which grow further during annealing. Routes to optimize this process go through the minimization of H precipitation in the pure Si regions. This can probably be achieved by optimizing the implantation conditions. © 2017