Studies on damage and annealing behaviours of top silicon in SOI material formed by N+ implantation

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 B+ at 25 keV with dose of 1 x 1015/cm2 and annealed in dry N2 ambient at different temperatures in the range of 500 C deg to 900 C deg 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 the silicon during post annealing in the temperature range from 500 C deg to 600 C deg, and no solid phase epitaxial regrowth is found when the temperature is increased to 900 C deg. Spreading resistance probe measurements show that the activation rate of implanted boron 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) or by the solid phase epitaxial regrowth