We have recently demonstrated a new implantation technique called SPIMOX (separation by plasma implantation of oxygen) to synthesize silicon-on-insulator structures using plasma immersion ion implantation (PIII) process. the implantation is performed by applying a large negative bias to a Si wafer immersed in an oxygen plasma created by an ECR source. Since the technique has no mass analysis, coexistence of O+ and O2+ ions in oxygen plasma can cause a non-Gaussian profile of the as-implanted oxygen distribution. We observed that during post-implantation annealing, the ripening process of the oxide precipitates depends on depth and concentration of the oxygen peaks. IN addition, implanted oxygen can migrate towards the Si surface during annealing, preventing a continuous buried oxide layer formation. IN this paper, we report our observation on the effect of the implantation profile on the competitions between internal oxidation at different depths and between internal and surface oxidation processes. With an additional He implantation, we demonstrate that the nucleation of oxide precipitation can be enhanced.

VPI-5 transforms to AlPO4–8 under mild thermal treatment (100 °C, 18 hrs). HRTEM micrographs, oriented normal to the c axis, show extensive defect-free regions in VPI-5, while slip planes normal to the c axis are found in AlPO4–8. Analysis of the HRTEM data, in conjunction with infrared and thermal analysis, adsorption studies and x-ray powder diffraction, has lead to a proposed structure for AlPO4–8. Though the sheets containing the 18 member rings which define the pores in VPI-5 remain intact in AlPO4–8, reduction in the porosity is attributed to blockages created by the movement of these sheets relative to each other.