Si+ was implanted into top silicon of SOI （silicon on insulator） material formed by N+ implantation to amorphize its surface

interface area between the top and the buried layer

and the whole top silicon. Then these SOI wafers and those without implantation were implanted by ET at 25 keV with dose of 1× 1015/cm2 and annealed in dry N2 ambient at different temperatures in the range of 500℃ to 900℃for 30 min. Glancing RBS/C measurement has shown that a solid phase epitaxial regrowth from the inner part of top silicon towards the surface or in the opposite direction exists respectively during post annealing if the surface or interface area of top silicon is amorphized. When the whole top silicon is amorphized

there is a phase transition from amorphous silicon to polysilicon for top silicon during post annealing in the temperature range from 500℃ to 600℃

and no solid phase epitaxial regrowth is found when the temperature is increased to 900℃. Spreading resistance probe measurements show that the activation rate of implanted boroh in the top silicon is lower than that in crystalline bulk silicon. The activation rate of implanted boron in the top silicon can be increased either by using Si+ implantation （to amorphize the surface or the interface area of top silicon） and the solid phase epitaxial regrowth.